Datron World Communications G25RMV110 VHF Mobile Radio User Manual G25AMK005a

Datron World Communications Inc VHF Mobile Radio G25AMK005a

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ii GUARDIAN VHF 110W MOBILE NOTICE TO USER WARNING! Maintain a distance of at least 3 feet (1 meter) between the antenna and people. To satisfy RF exposure compliance, you, as a qualified user of this radio device must control the exposure conditions of bystanders to ensure the minimum distance is maintained between the antenna and nearby persons. The operation of this transmitter must satisfy the requirements of the Occupational/Controlled Exposure Environment for work-related use. Transmit only when people are at least the minimum distance from the properly installed, externally mounted antenna. This radio is designed for initial setup by authorized technicians using a computer and the GuardianTM programming software. Programming can enable or disable many of the radio’s features from user access per user agency security policy and legal restrictions. All, some, or none of the features and functions described in this manual may be available to the user. To successfully operate the radio, it is important to understand how the radio is programmed prior to issuance by the user agency. Consult authorized agency personnel for features and functions made available or restricted to the user. FCC licensees are prohibited by federal law from enabling the radio to directly enter transmit frequencies using the radio's controls. NOTICE TO INSTALLATION TECHNICIANS Use only a manufacturer- or dealer-supplied antenna. Antenna minimum safe distance: 3 feet (1 meter). The Federal Communications Commission (FCC) has adopted a safety standard for human exposure to Radio Frequency (RF) energy that is below the Occupational Safety and Health Act (OSHA) limits. Antenna mounting: The antenna supplied by the manufacturer or radio dealer must be mounted at a location so that during radio transmission people cannot come closer than the minimum safe distance to the antenna, i.e., 3 feet (1 meter). To comply with current FCC RF exposure limits, the antenna must be installed at or exceeding the minimum safe distance, and in accordance with the requirements of the antenna manufacturer or supplier. Base station installation: The antenna should be fixed-mounted on an outdoor permanent structure. Address RF exposure compliance at the time of installation. Antenna substitution: Do not substitute any antenna for the one supplied or recommended by the manufacturer or radio dealer. You may be exposing people to harmful RF radiation. Contact your radio dealer or manufacturer for further instructions.

GUARDIAN VHF 110W MOBILE iii CONTENTS CHAPTER 1: GENERAL INFORMATION ................................................................................................. 1-1 1.1 SCOPE ......................................................................................................................................................... 1-1 1.2 GENERAL DESCRIPTION .............................................................................................................................. 1-1 1.3 PERFORMANCE SPECIFICATIONS ................................................................................................................. 1-1 CHAPTER 2: HARDWARE THEORY OF OPERATION.......................................................................... 2-1 2.1 INTRODUCTION ........................................................................................................................................... 2-1 2.2 SYSTEM SPECIFICATIONS ............................................................................................................................ 2-1 2.3 SYSTEM BLOCK DIAGRAM .......................................................................................................................... 2-2 2.4 RECM CONTROL HARDWARE THEORY OF OPERATION.............................................................................. 2-4 2.4.1 Control Logic ..................................................................................................................................... 2-4 2.4.2 DSP .................................................................................................................................................... 2-7 2.4.3 Flash ROM ......................................................................................................................................... 2-7 2.4.4 RAM .................................................................................................................................................. 2-7 2.4.5 TCXO................................................................................................................................................. 2-7 2.4.6 FPGA ................................................................................................................................................. 2-8 2.4.7 IF ADC............................................................................................................................................... 2-8 2.4.8 Clock Generation ............................................................................................................................... 2-8 2.4.9 Logic Audio CODEC......................................................................................................................... 2-8 2.4.10 Accessory Connector Interface and Filtering .....................................................................................2-8 2.4.11 Transceiver Interface and Filtering .................................................................................................... 2-8 2.4.12 Keypad Interface ................................................................................................................................ 2-8 2.4.13 Audio Interface................................................................................................................................... 2-8 2.4.14 Test Interface...................................................................................................................................... 2-9 2.4.15 LED.................................................................................................................................................... 2-9 2.4.16 RECM Power Consumption............................................................................................................... 2-9 2.5 RECM TRANSCEIVER SECTION .................................................................................................................. 2-9 2.5.1 Interface Section................................................................................................................................. 2-9 2.5.2 Receiver Section............................................................................................................................... 2-10 2.5.3 Digital/Analog Control..................................................................................................................... 2-13 2.5.4 Keypad Microcontroller ................................................................................................................... 2-14 2.6 AUDIO AMPLIFIER BOARD ........................................................................................................................ 2-14 2.6.1 Description ....................................................................................................................................... 2-14 2.6.2 Power Conditioning ......................................................................................................................... 2-14 2.6.3 Communication with Transceiver .................................................................................................... 2-15 2.6.4 Audio Amplifiers ............................................................................................................................. 2-15 2.6.5 Power Levels Detector, Converter, and RF/DC Combiner .............................................................. 2-15 2.6.6 PA ON/OFF Control (Bypass Mode)............................................................................................... 2-16 2.6.7 RF Power Indication ........................................................................................................................ 2-16 2.6.8 Audio Board Block Diagram............................................................................................................ 2-16 2.7 DISPLAY BOARD ....................................................................................................................................... 2-17 Figure 2-4: Guardian Keypad Board............................................................................................................... 2-17 2.7.1 Control Logic Interface .................................................................................................................... 2-18 2.7.2 Keypad ............................................................................................................................................. 2-18 2.7.3 Switch Interface ............................................................................................................................... 2-18 2.8 FRONT PANEL INTERFACE BOARD ............................................................................................................ 2-18 CHAPTER 3: SOFTWARE THEORY OF OPERATION ........................................................................... 3-1 3.1 FUNCTIONAL SYSTEM OPERATION.............................................................................................................. 3-1 3.1.1 General ............................................................................................................................................... 3-1 3.1.2 Guardian Block Diagram ................................................................................................................... 3-1 3.1.3 Architecture........................................................................................................................................ 3-2 3.1.4 Board Identification ........................................................................................................................... 3-2

iv GUARDIAN VHF 110W MOBILE 3.1.5 Self-Test on Power-Up....................................................................................................................... 3-2 3.1.6 Flash Software Upgrades ................................................................................................................... 3-2 3.1.7 Voice Coder/Decoder (VOCODER).................................................................................................. 3-2 3.2 RADIO CONTROL SOFTWARE ...................................................................................................................... 3-2 3.2.1 Audio Control .................................................................................................................................... 3-2 3.2.2 DSP Control Software........................................................................................................................ 3-2 3.2.3 Transceiver Board .............................................................................................................................. 3-3 3.2.4 DC Power Control.............................................................................................................................. 3-5 3.2.5 Monitoring ......................................................................................................................................... 3-5 3.2.6 Radio Control Drivers ........................................................................................................................ 3-5 3.3 DIGITAL SIGNAL PROCESSING..................................................................................................................... 3-6 3.3.1 DSP Transmit Chain .......................................................................................................................... 3-6 3.3.2 DSP Receive Chain ............................................................................................................................ 3-8 3.3.3 DSP Software................................................................................................................................... 3-11 3.4 KEYPAD MPU SOFTWARE ........................................................................................................................ 3-11 3.4.1 Overview.......................................................................................................................................... 3-11 3.4.2 General ............................................................................................................................................. 3-11 3.4.3 Keypad Scanning ............................................................................................................................. 3-11 3.4.4 Push-to-Talk (PTT) Input................................................................................................................. 3-11 3.4.5 Switch Input ..................................................................................................................................... 3-11 3.4.6 LED Output...................................................................................................................................... 3-11 3.4.7 Backlight Control ............................................................................................................................. 3-11 3.4.8 Serial Interface ................................................................................................................................. 3-11 3.5 DATA INTERFACE...................................................................................................................................... 3-12 3.5.1 CAI Data Interface ........................................................................................................................... 3-12 3.5.2 Synchronous Serial Data Interface................................................................................................... 3-12 3.5.3 CAI Data Link Layer ....................................................................................................................... 3-12 3.5.4 Transmit Physical Link Layer .......................................................................................................... 3-13 3.5.5 Receive Physical Link Layer............................................................................................................ 3-14 3.5.6 DES Encryption ............................................................................................................................... 3-14 3.5.7 Host Interface................................................................................................................................... 3-15 3.5.8 Flash Interface.................................................................................................................................. 3-15 3.5.9 Paging............................................................................................................................................... 3-15 3.5.10 Hardware Control............................................................................................................................. 3-16 3.6 CONTROLLER SOFTWARE.......................................................................................................................... 3-16 3.6.1 Overview.......................................................................................................................................... 3-16 3.6.2 Environment..................................................................................................................................... 3-16 3.6.3 Radio Store....................................................................................................................................... 3-18 3.6.4 Program/Fill/Control Interface......................................................................................................... 3-19 3.7 USER INTERFACE ...................................................................................................................................... 3-20 3.7.1 Display ............................................................................................................................................. 3-20 3.7.2 Optional DTMF Microphone ........................................................................................................... 3-20 CHAPTER 4: INSTALLATION, ADJUSTMENT, AND OPERATION .................................................... 4-1 4.1 RADIO CONFIGURATION ............................................................................................................................. 4-1 4.1.1 Channels............................................................................................................................................. 4-1 4.1.2 Zones.................................................................................................................................................. 4-1 4.1.3 Banks.................................................................................................................................................. 4-1 4.2 INSTALLATION AND ADJUSTMENT .............................................................................................................. 4-1 4.2.1 Hardware............................................................................................................................................ 4-1 4.2.2 Software ............................................................................................................................................. 4-1 4.3 OPERATING PROCEDURES ........................................................................................................................... 4-1 4.3.1 Connect the Power Source ................................................................................................................. 4-1 4.3.2 Connect the Antenna .......................................................................................................................... 4-1 4.3.3 Optional External Speaker ................................................................................................................. 4-1 4.3.4 Radio Programming ........................................................................................................................... 4-1

GUARDIAN VHF 110W MOBILE v 4.3.5 Radio Power Up ................................................................................................................................. 4-2 4.3.6 Choose a Channel............................................................................................................................... 4-2 4.3.7 Transmit a Voice Message ................................................................................................................. 4-2 4.3.8 Receive a Voice Message................................................................................................................... 4-2 4.3.9 Programming and Bypass Mode ........................................................................................................ 4-2 CHAPTER 5: RADIO SET AND ACCESSORIES ....................................................................................... 5-1 5.1 SYSTEM DESCRIPTION ................................................................................................................................5-1 5.1.1 Mobile Radio...................................................................................................................................... 5-1 5.1.2 Antenna .............................................................................................................................................. 5-1 5.1.3 Guardian PC Programmer .................................................................................................................. 5-1 5.1.4 Cloning Cable..................................................................................................................................... 5-2 5.2 CONTROLS, INDICATORS, AND CONNECTORS ............................................................................................. 5-2 5.2.1 Controls.............................................................................................................................................. 5-2 5.2.2 Indicators............................................................................................................................................ 5-3 5.2.3 Connectors ......................................................................................................................................... 5-4 5.3 TRANSCEIVER CHARACTERISTICS ............................................................................................................... 5-4 5.3.1 Transmitter Characteristics ................................................................................................................ 5-4 5.3.2 Receiver Characteristics..................................................................................................................... 5-5 5.4 COMMUNICATION SECURITY ...................................................................................................................... 5-5 5.4.1 Algorithms ......................................................................................................................................... 5-5 5.4.2 Keyfill ................................................................................................................................................ 5-5 5.4.3 Zeroize ............................................................................................................................................... 5-6 CHAPTER 6: SERVICING THE RADIO...................................................................................................... 6-1 6.1 GENERAL .................................................................................................................................................... 6-1 6.2 SELF-TEST AT POWER UP........................................................................................................................... 6-1 6.3 CAUTION..................................................................................................................................................... 6-1 CHAPTER 7: TROUBLESHOOTING........................................................................................................... 7-1 7.1 INTRODUCTION ........................................................................................................................................... 7-1 7.2 RADIO FUNCTIONAL TESTS......................................................................................................................... 7-1 7.2.1 Power-On Test ................................................................................................................................... 7-1 7.2.2 Buttons and Switches Test ................................................................................................................. 7-1 7.2.3 Transmit Test ..................................................................................................................................... 7-1 7.2.4 Receive Test....................................................................................................................................... 7-1 7.2.5 Audio Test.......................................................................................................................................... 7-1 CHAPTER 8: DEFINITIONS ......................................................................................................................... 8-1 CHAPTER 9: SIGNAL TONES...................................................................................................................... 9-1 CHAPTER 10: INTERFACE ...............................................................ERROR! BOOKMARK NOT DEFINED. 10.1 ACCESSORY CONNECTOR PINS AND FUNCTIONS....................................................................................... 10-1 CHAPTER 11: SCHEMATICS ....................................................................................................................... 11-1 FIGURES Figure 2-1: Guardian Interconnect Diagram ............................................................................................................. 2-3 Figure 2-2: Guardian Control Logic ......................................................................................................................... 2-4 Figure 2-3: RECM Power Supply ............................................................................................................................. 2-5 Figure 2-4: Guardian Keypad Board.......................................................................................................................2-17 Figure 3-1: Guardian Block Diagram........................................................................................................................3-1 Figure 3-2: Transmit DSP Chain...............................................................................................................................3-7 Figure 3-3: Receive DSP Chain ................................................................................................................................3-8 Figure 3-4: Controller Software..............................................................................................................................3-16

GUARDIAN VHF 110W MOBILE 1-1 CHAPTER 1: GENERAL INFORMATION 1.1 Scope This manual provides technical information for the Guardian 110 Watt mobile radio system.. This chapter gives a general description and provides a system block diagram. Chapters 2 and 3 provided detailed theory of operation for hardware and software portions of the radio. Chapter 4 provides general operation of the radio. Chapter 5 is the physical description of the radio components and the available accessories. Chapters 6 and 7 describe servicing, testing, and troubleshooting the radio system. The remaining chapters provide additional technical information and schematics. 1.2 General Description The Guardian 110W mobile radio system is compliant with the APCO project 25 FDMA common air interface, and is also compatible with conventional wideband FM systems and newer narrowband FM systems. It provides fully digital encrypted communication suitable for use by modern public safety and commercial users. The radio system is built from a remote power amplifier and a control head. The 110W RF power amplifier mounts in a remote location such as a vehicle trunk, while the control unit is mounted in the cabin. The two are connected by a single coaxial cable. The cable carries both the RF signal and control signals (PTT, and power level setting). 1.3 Performance Specifications Model Designation Guardian VHF Mobile Radio General Model G25RMV110 Frequency Range 136.000 to 174.000 MHz Banks, Zones, Channels, Shadow 4 banks, 16 zones, 256 channels, 7 shadow Voice Digital Mode Voice Coding Frame Re-sync Interval Error Correction Method IMBE™ 4.4 kb 180 msec RS, golay, hamming Input Voltage 13.6 Vdc, negative chassis ground Current Drain @ 13.8V: Standby Receive @ Rated Audio Transmit @ Rated Power 0.5A 3.0A 28.0A Mounting Dashboard mounted, including bracket Dimensions 2.75” x 7.1” x 5.5” (H x W x D) Weight Control Head Remote Unit 2.5 lb 12 lb Case Metal and plastic Temperature Range -30° to +60°C Channel Spacing 12.5 and 25 kHz, selectable in 2.5 or 3.125 kHz steps FCC Type Acceptance Number Pending Industry Canada Pending

1-2 GUARDIAN VHF 110W MOBILE Model Designation Guardian VHF Mobile Radio Receiver (Measurements per TIA/EIA 603 Standards) Sensitivity Digital Mode: 5% BER Analog Mode: 12 dB SINAD -116 dBm or greater Spurious -70 dB Intermodulation -70 dB Audio Output Power 10W, 4Ω external, 5W, 8Ω internal speaker Audio Distortion (at 1000 Hz) 3% Frequency Stability (-30° to 60°C) ± 1 ppm Maximum Frequency Separation Full-band split Transmitter (Measurements per TIA/EIA 603 Standards) RF Power Output 25W to 110W, adjustable Spurious and Harmonic Emissions -70 dB FM Hum and Noise (wideband) -46 dB @ 25 kHz/-40 dB @ 12.5 kHz FCC Modulation Designators 16K0F3E, 11K0F3E, 20K0F1E Audio Distortion (at 1000 Hz) 2% Audio Response (1000 Hz Ref.) ± 3 dB, 300 to 3000 (EIA/TIA 603) Frequency Stability (-30°C to 60°C) ± 2.5 ppm Maximum Frequency Separation Full bandwidth Environment Specifications (MIL-SPEC) Environment 810C 810D 810E Method Procedure Method Procedure Method Procedure Low Pressure 500.1 I 500.2 I 500.3 II High Temp. 501.1 I, II 501.2 I, II 501.3 I, II Low Temp. 502.1 I 502.2 I 502.3 I Temp. Shock 503.1 I 503.2 I 503.3 I Solar Radiation 505.1 I 505.2 I 505.3 I Humidity 507.1 II 507.2 II (5) 507.3 II (5) Salt Fog 509.1 I 509.2 I 509.3 I Dust and Sand 510.1 I 510.2 I 510.3 I, II Vibration 514.2 VII(W) 514.3 I (1) 514.4 I (1) Shock 516.2 I, II, V 516.3 I 516.4 I

GUARDIAN VHF 110W MOBILE 2-1 CHAPTER 2: HARDWARE THEORY OF OPERATION 2.1 Introduction The Control Module contains the Receiver Exciter Control Module (RECM), Audio amplifier board, Interface board, and display and keypad assemblies. The RECM is a shielded assembly containing the transceiver and all control and signal processing hardware and firmware, except the RF and audio power amplifiers. The trunk-mounted RF power amplifier contains a single PC assembly. Schematics for all the boards are located in the back of the manual. 2.2 System Specifications Table 2-1: Guardian G25RMV110 Technical Specifications Specification Description General Frequency Range 136.000 to 174.0000 MHz Banks, Zones, Channels, Shadow 4 banks, 16 zones, 256 channels, 7 shadow Voice Digital Mode Voice Coding IMBE 4.4 kb Frame Re-sync Interval 180 msec Error Correction Method RS, golay, hamming Mounting Under dashboard using bracket Dimensions 2.94”x7.13”x7.06” (H x W x D) Weight 5 lbs. Approximately Case Metal and plastic Temperature Range -30° to +60°C Channel Spacing 12.5 and 25 kHz, selectable in 2.5 or 3.125 kHz steps FCC Type Acceptance Number Pending Industry Canada Pending Receiver (Measurements per TIA/EIA 603 Standards) Sensitivity Digital Mode: 5% BER Analog Mode: 12 dB SINAD -116 dBm maximum Spurious -70 dB Intermodulation -70 dB Audio Output Power 5W internal, 10W external speaker Audio Distortion (at 1000 Hz) 5% Frequency Stability (-30° to +60°C) ±2.5 ppm Maximum Frequency Separation Full-band split Transmitter (Measurements per TIA/EIA 603 Standards) Duty Cycle 3%, 3 min continuous RF Power Output 25W, 50W, 110W; also bypass mode Spurious and Harmonic Emissions -70 dB FM Hum and Noise (wide/narrowband) -48/-47 dB typical FCC Modulation Designators 11K0F3E, 16K0F3E, 22K0F3E, 14K6F1E Audio Distortion (at 1000 Hz) 5% Audio Response (1000 Hz Ref.) ±3 dB 300 to 3000 (EIA/TIA 603) Frequency Stability (-30° to +60°C) ±2.5 ppm

2-2 GUARDIAN VHF 110W MOBILE Specification Description Maximum Frequency Separation Full bandwidth DES Encryption Encryption Keys 16 Code Key Generator External SBCF Analog DES Encryption Standard feature Environmental Specifications MIL-STD-810F Test Method/Procedure Low Pressure (Altitude) 500.4/II High Temperature 501.4/I, II Low Temperature 502.4/I Temperature Shock 503.4/I Solar Radiation (Sunshine) 505.4/I Humidity 507.4/I Salt Fog 509.4/I Sand and Dust 510.4/I, II Vibration 514.5/I Shock 516.5/I Standard Accessories Optional Accessories 5W Internal Speaker 10W External Speaker Palm Microphone DTMF Microphone Mounting Bracket Key Variable Loader 14 ft Power Cable 25 ft Power Cable 2.3 System Block Diagram

GUARDIAN VHF 110W MOBILE 2-3 Control HeadMounted Power AmplifierCoaxControlCableAntenna ConnectionIn/OutFused DC CablePower ON/OFF and R/TswitchesControlPowerspliteroutput powercontrol monitorFilter&combinerAMPAMPpower sensorRRTTFused DC PowerDB9Speaker outIgnition and Emergency SwitchDB25System Control andProgrammingRECMPAcontrolFront panel interface(LCD,Keypad and switches)MICconnectorDTMFcontrolDCconnector Figure 2-1: Interconnect Block Diagram

2-4 GUARDIAN VHF 110W MOBILE 2.4 RECM Control Hardware Theory of Operation 2.4.1 Control Logic The control logic interfaces to the keypad logic, transceiver, internal audio, and Motherboard. The control logic implements the main radio control function and all the baseband signal processing. TCVR ModuleDB25 Accessory ConnectorPower SupplyKeypad Board and Front Panel InterfaceGrey areas connectthrough the 80-pin connector on theMotherboard. Figure 2-2: Guardian Control Logic 2.4.1.1 Power Supply Unit This block of circuitry takes the 7.8V regulated voltage together with a number of control signals to generate a number of power supply outputs.

GUARDIAN VHF 110W MOBILE 2-5 2.4.1.2 On/Off Switching The main continuous supply 10V control is passed through a front panel on/off switch to generate 10V SW from the main radio supply. In normal operation the on/off switching is controlled by the radio on/off rotary switch by the control /RADON. Once switched on the main controller can hold the radio on by setting PWRHOLD. In addition to the radio rotary on/off switch, the on/off switching can be controlled by the external line /RADOFF via the accessory connector. This line overrides the /RADON line and can be used to force the radio off regardless of the rotary switch setting. However, the H8 controller uses the PWRHOLD and PWROFF lines to implement a clean controlled switch off. Figure 2-3: RECM Power Supply 2.4.1.3 Transmit Power Switching A single FET switch controlled by CTX is used to provide a switched 10VTX high-current supply (1.5A) for the transmitter. 2.4.1.4 4.5V Switch Mode Power Supply This circuit uses a switch mode power supply device to generate a 4.5V supply at 450 mA maximum for the radio logic. The switch mode device is synchronous and uses an externally provided power supply clock at 384 kHz. The power supply circuit includes input and output filters to limit the conduction of the fundamental switching components and their harmonics in the VHF band, both onwards into the logic and back into the power supply.

2-6 GUARDIAN VHF 110W MOBILE 2.4.1.5 3.3V Linear Logic Supply The output from the 4.5V switch mode power supply is passed through 3.3V linear power supplies to remove any remaining power supply switching noise on the main logic supply. One 3.3V supply is used for control logic, the other 3.3V, 50 mA supply is used for control logic analog circuitry. 2.4.1.6 Reset Generator This circuit uses a MPU supervisory device (MAX825) to generate a reset pulse of at least 140 ms whenever the 3.3V logic supply drops below 3.08V. The circuit also generates a reset signal when the watchdog input is asserted by H8 or DSP. 2.4.1.7 5V Linear Logic Supply This circuit generates a 5V logic supply at 50 mA maximum for use on the control logic. 2.4.1.8 Audio Supplies Two linear regulators providing clean filtered supplies for the audio at 5V are provided. The audio power amplifiers use the 5V, 800 mA audio supply. The audio supply is used for the low-current microphone amplifier. A linear 5V bias supply to the internal microphone is also provided. 2.4.1.9 H8 Microcontroller H8 is the main controller for the radio and is a HD6433044 ROM-less microcontroller. H8 is configured with an expanded bus connected to the Flash, RAM, and DSP. The H8 integral bus arbitration logic allows H8 and DSP to both have access to the Flash and RAM. H8 is clocked by the external TCXO. H8 is powered from the 3.3V logic supply, and reset by the hardware /RES line. A watchdog output to the hardware-reset circuitry is provided. H8 generates chip select outputs to allow the Flash, RAM, FPGA, and DSP host port to be separately addressed. One serial port of H8 is used to implement a bidirectional synchronous serial interface to the keypad board. This interface is used to communicate with the keypad MPU and directly load the LCD controller. The clock on this interface runs at 100 kHz. An associated interrupt input to H8 is used to initiate transfers from the keypad to H8. This serial interface is also used to load the output expander in the FPGA, and also to configure the FPGA. One serial port of H8 is used to implement a bidirectional asynchronous serial interface to an external PC used for programming, filling, and controlling the radio. This interface uses programmable standard baud rates (default 9600 baud) and standard data formats. There are no handshaking parallel lines associated with this interface. Two parallel I/O lines on H8 are used to generate an I2C interface to allow the EEPROM on the transceiver to be accessed. Four parallel output lines on H8 are used to generate a synchronous serial output bus with clock and data and separate strobe lines for the DAC, control shift register, and synthesizer on the transceiver. One H8 DAC output is used to generate simple audio tones of varying volume for use as audio alerts. The second H8 DAC output is available for VCTCXOP control. The six-channel ADC is used to measure: the raw supply voltage, WRU radio input, reference crystal temperature, PA temperature, PA current, and RSSI. Two I/O lines are used to implement software UART, used for debug outputs in the development environment. 2.4.1.10 H8 Input Requirements The total requirements for parallel input signals to H8, which need to be polled on a regular basis are:  OOL: Out-of-lock (OOL) signal from the transceiver synthesizer  EXT PTT: External PTT  PWROFF: On/off switch position  CONFDONE: Configuration status of FPGA 2.4.1.11 H8 Output Requirements The total requirements for parallel output signals from H8, which need to be controlled are as below. A serial load output latch in the FPGA expands the output capabilities of H8.

GUARDIAN VHF 110W MOBILE 2-7  LCDA0: LCD controller A0 command/ data select  LCDCS: LCD chip select  SCL: I2C and synthesizer clock  DACSDA: Transceiver serial data, synthesizer, DAC, S-R  SYNTHENA: Synthesizer framing pulse  DACENA: DAC framing pulse  SRENA: S-R framing pulse  /DINT: Interrupt to DSP from H8  /RESO: Watchdog output from H8 2.4.1.12 H8 Input/Output Requirements The total requirements for parallel input/output signals on H8, which need to be read and controlled are:  BATBUS: Not used in the mobile configurations  SDA: I2C data 2.4.1.13 H8 Input Interrupt Requirements The total requirements for parallel input interrupt signals on H8 are:  LBOUT: Not used in the mobile configuration  DSPINT DSP: Interrupt 2.4.2 DSP The DSP56309 (or DSP56302) processor implements all baseband signal-processing functions in the radio. It interfaces with the transceiver through one ESSI port, to the user for voice through the second ESSI port. The DSP function is controlled by H8 through the DSP host port. The DSP has direct access to the main Flash memory through the bus arbitration logic in H8, this allows it to download program images. The initial power-on code download is through the host port. The hardware-reset line resets the DSP. The TCXO clock output line clocks the DSP at 12.288 MHz. The DSP ESSI 1 port is used to provide a synchronous interface to the IF ADC and the transceiver 12-bit DAC. In receive modes that interface is capable of writing to the DAC at 48 ksps while still reading the ADC at 96 ksps. The DSP ESSI “0” port is used to provide a full-duplex synchronous interface to the audio CODEC using 8 kHz sampling rate and 13 bit samples. The data transfer is at 2.048 MHz using a DSP sourced clock and framing pulse. 2.4.3 Flash ROM A 512k x16 Flash ROM is used as the main program store for the H8 controller and DSP. The Flash ROM uses a protected boot sector that is factory programmed via the DSP JTAG port. Normal reprogramming is implemented by running H8 from the boot sector and using 3V, programming the bulk of the device. The Flash is used to provide a parameter storage area for nonvolatile data storage of frequencies and keys, etc. This storage area is capable of in excess of 100k write cycles. 2.4.4 RAM A 128k x 8 static RAM is used for temporary storage of data by the H8 controller. This RAM is powered by a continuous supply that maintains its contents as long as a power source is present. Additionally the RAM has a backup capacitor to retain its contents over power interruptions. 2.4.5 TCXO This oscillator serves as the reference for all logic and power supply clocks within the control logic and keypad. It provides the data rate clocks for radio operation, and is the source of the ADC/DAC/CODEC conversion clocks. The TCXO is at 12.288 MHz, with a temperature tolerance of +2.5 ppm. Additional calibration is performed to provide a typical temperature tolerance of ± 1.0 ppm, a trimmer to set the initial frequency is provided. A Schmitt trigger buffer squares up the TCXO sine wave output before being output to H8 and DSP.

2-8 GUARDIAN VHF 110W MOBILE 2.4.6 FPGA The control logic uses an Altera 8282 FPGA device to provide a flexible serial data routing function, I/O expansion for H8 and DSP, clock generation, data multiplexing, and to absorb discrete logic functions. The synchronous serial bus routing function involves routing the synchronous serial port of H8 either to the keypad and LCD, or to the I/O expansion in the FPGA. High-order address pins from H8 control this routing and a FPGA dummy write with dedicated FPGA chip select from H8. The FPGA includes a serial load parallel output shift register that is used for parallel output expansion for H8. The discrete logic functions of the FPGA, includes logic to control an inverter for one of the LCD control outputs. The data multiplexing function involves rerouting serial pins between the accessory connector and the DSP SCI port to allow data transmission and keyfill operations. 2.4.6.1 FPGA Configuration The FPGA is configured at start-up from the main Flash memory using a serial load from H8. During configuration outputs are tri-stated and pulled to a safe level by committing resistors to prevent audio and RF bursts at power up. 2.4.7 IF ADC The IF sampling ADC is a 12-bit ADC capable of sub-sampling a 455 kHz, IF signal at 96 kHz sampling rate. It is connected by a serial interface to the DSP ESSI port 1. The serial data interface is clocked at 1536 kHz. 2.4.8 Clock Generation The clock generation logic is used to generate clocks for the synchronous power supplies, the ADC serial interface, and the keypad microcontroller. The clock generator logic is implemented in the FPGA. 2.4.9 Logic Audio CODEC The audio CODEC is an integrated ADC/DAC and audio filter device capable of full-duplex operation on voice bandwidth signals at 8 ksps. The samples have a resolution of 13-bits linear. The CODEC is connected to the DSP ESSI port “0” with serial data transfer rate of 2.048 MHz. The CODEC is continuously powered from the 3V logic and 3V audio supplies. DSP parallel control lines are used to mute the input and output sections as required. 2.4.10 Accessory Connector Interface and Filtering All outputs are filtered to limit their bandwidth to the minimum and current limited to protect them from output short circuits to ground or up to 16V. All inputs are filtered and protected from continuous application of ground or +16V. There is no protection against negative applied voltages. Inputs and outputs are protected from static discharge of at least 10 kV air discharge. All inputs and outputs incorporate RF bypass filter capacitors adjacent to the connector, except for ground. 2.4.11 Transceiver Interface and Filtering Most of the signals crossing the interface are filtered to limit their bandwidth to the minimum consistent with correct operation. Outputs from the control are filtered with series resistors on the RECM and grounded capacitors on the transceiver adjacent to the connector. Outputs from the transceiver to the control use the reverse configuration. 2.4.12 Keypad Interface Some filtering is provided on this interface, but all outputs are protected from short circuits by series resistors. Where possible, inputs are also protected from damage by series resistors. 2.4.13 Audio Interface The audio interface is implemented with four-way wire connectors directly via the 80-pin interface through the Motherboard to the integral speaker and microphone.

GUARDIAN VHF 110W MOBILE 2-9 2.4.14 Test Interface The test interface provides the following functions:  Joint test action group (JTAG) connector access for board test and Flash boot sector programming  Board reset and control access  Board power supply and on-off switching access  H8 serial debug port access 2.4.15 LED The control logic incorporates a 3-color LED used for status information. It is controlled by the FPGA to show red, green, or off. It is optically coupled to the top face of the radio by a light pipe. The hardware is configured so during hardware reset, before the keypad MPU software is running, the LEDs are off. 2.4.16 RECM Power Consumption The control logic operates at input voltage 7.7V. The average current consumption of the control logic is:  Standby mode: 60 mA  Receive mode @ 500 mW: 330 mA  Transmit mode @ 2W: 1,000 mA  Transmit mode @ 5W: 1,500 mA 2.5 RECM Transceiver RF shields covers the board. 2.5.1 Interface J2 is the transceiver antenna connector. RF signals are transmitted and received through this surface mount RF connector. Transmitted and received RF signals are routed from this connector through a short RF cable to the RX/TX relay on the Motherboard. 2.5.1.1 Transmit Chain The pre-driver amplifier (Q7, etc.) amplifies the TXLO signal from the synthesizer section. The Q7 output power is typically 13 dBm measured at C77/R44/R49 node. R44, R49, and R52 are part of a 3 dB pie attenuator network. The gain control is made up of CR5, CR6, and associated components. This circuit yields more than 50 dB of useful attenuation range. The circuit is part of a DAC controlled closed loop system, in conjunction with the detector/power control circuit (U12, U13, and associated components), which controls the transmitter output power level. The power amplifier (PA) is a Mitsubishi M68776, 7.2V, 6W gained controlled power amplifier. The harmonic filter (C209, L30, C81, C82, L31, C83, and C84) attenuates harmonics created by the power amplifier. The harmonic filter insertion loss is 0.4 dB typically at 174 MHz. The output of the harmonic filter connects to the 20 dB coupler (U12). This coupler is part of a DAC-controlled closed loop system designed to set the transmitter output power level. The insertion loss through the coupler (U12-1 to U12-3) is 0.2 dB typically. 2.5.1.2 Power Amplifier Control Transmit output power level is controlled by the detector/power control circuit and the gain control amplifier input via VCONTROL. This closed loop system is designed to keep the transmitter output power constant over variations in temperature, transmitter supply voltage (7.5VT), and RF power levels into the transmit chain. The detector/power control circuit is made up of the 20 dB coupler (U12), an RF rectifier circuit (CR11, CR12, etc.), and an integrator (U13). The DAC line labeled PWRSET at the non-inverting input of U13 sets the transmitter to the desired power level. U12-2 samples the transmit signal. The sampled RF signal is rectified by the temperature stable circuitry of CR11, CR12, etc, and is routed to the inverting input of the integrator at U13-4. The output of the integrator at U13-1, labeled VCONTROL, controls the gain of the power amplifier. Any change in transmitter output power level is automatically corrected by the loop.

2-10 GUARDIAN VHF 110W MOBILE 2.5.1.3 PIN Diode Switch The antenna PIN diode switch is made up of CR7, CR8, CR9, CR10, and other associated components. This switch is a four-port design. The four ports are antenna 1 (TOP RF), antenna 2 (SIDE RF), receive, and transmit. Receive and transmit ports can be switched to only one of the two antenna ports. Transmit signals are routed from the transmit/receive PIN diode switch (to be discussed in the following paragraph) to the antenna port. The receive signal is routed from the selected antenna port to the transmit/receive PIN diode switch. The antenna PIN diode switch and receiver circuits share current in the receive mode of operation via the signal labeled RXSINK at Q11, pin 3. The insertion loss through the antenna pin switch is 0.2 dB typically. The transmit/receive PIN diode switch is made up of C6, L60, L38, L40, L39, D9, D7, D10, C97, C98, C104, C105, C106, C107, and other associated components. C127, C114, L42, and C115 are the 1/4 wave simulator circuit. The 1/4 wave simulator is critical to the design of the switch. In the transmit mode of operation CR13 and CR14 are forward biased. C116 resonates with the internal series inductance of CR14 at 155 MHz and the receive port (RX INPUT) is RF shorted to ground. With the receive port RF shorted to ground; the parallel combination of C127, C114, and L42 forms a tank circuit resonating at 155 MHz. Consequently, the receive port appears as an open circuit to the transmit signal and is routed to the antenna PIN diode switch. In the receive mode of operation, CR13 and CR14 are biased off so C114/L42/C115 appears as a low-pass filter (LPF) to signals at the antenna port of the switch. The insertion loss through the transmit/receive PIN diode switch is 0.4 dB in the transmit mode and 0.2 dB in the receive mode typically. Q10 to Q19 and associated components are switching transistors used to control the antenna and transmit/ receive PIN diode switches. The current flowing through the entire PIN diode circuit is approximately 45 mA in the transmit mode of operation. In the receive mode of operation the transmit/receive PIN diode switch is disabled, and nominal 85 mA flows through the antenna PIN diode switch. 2.5.2 Receiver The VHF signal enters into the RX INPUT via the PIN diode switch (discussed previously). D1 and D2 are Schottky protection diodes to protect the front-end circuitry from RF overloads that could occur if the PIN diode switch failed to work properly or if a transmitter is very close to a receiver. Typical insertion loss is 0.1 dB for the protection diodes. L25/C61 form a band-stop filter (BSF) at the first IF frequency of 45 MHz. Typical insertion loss for the BSF is 15 dB at 45 MHz but less than 0.1 dB in the VHF band. L14, L6, CR3, CR4, L7, CR27, CR28, L8, and L15 make up the very high frequency (VHF) preselector band-pass filter (BPF). The BPF is inductively coupled for improved high-side attenuation. This filter provides attenuation to spurious signals such as the first image and the half-IF. The BPF is varactor diode tuned by DAC line RXVTF. Typical insertion loss (138 to 174 MHz) is 1 dB for the VHF BPF. The RF amplifier (Q1, T1, etc.) utilizes loss-less feedback to deliver reasonable gain, low-noise figure, and a high third order intercept point simultaneously. Typical gain (136 to 174 MHz) is 11.5 dB for the RF amplifier. C14, L1, C9, C15, L2, C10, C16, L3, C11, C17, and L9 form a VHF LPF. This filter provides additional RX spurious attenuation as well as image noise attenuation. L4, C12, L16, C25, L5, and C13 form a BSF at the first IF frequency of 45 MHz. The insertion loss is 1.0 to 2.0 dB (136 to 174 MHz) typically for the cascade. The IF BSF insertion loss is typically 40 dB at 45 MHz, but less than 0.3 dB in the VHF band. U1 is a double-balanced mixer (DBM). U1 converts the desired RF signal down to the first IF of 45 MHz. High-side local oscillator (LO) injection is used. Therefore, the LO is 45 MHz higher than the receiver tuned frequency. The LO drive level is +10 dBm nominal at U1, pin 1. The conversion loss of the mixer (RF to IF) is 5.5 dB typically. The LO signal is generated in the synthesizer section (to be discussed later). The LO signal is designated RXLO on the schematic diagram. The LO signal is routed to a LPF consisting of C31, L21, C87, C30, L20, C75, and C28. L19 and C28 are also used to impedance match the LO port of the mixer. The insertion loss of the VHF LO LPF is 0.3 dB typically at 174 MHz. R4, L17, C6, L10, R5, and C23 make up the diplexer network. This network properly terminates the DBM both in and out of band. The diplexer also provides some additional half-IF spurious rejection. The diplexer insertion loss is 0.8 dB typically at 45 MHz.

$GUARDIAN VHF 110W MOBILE 2-11 There are two 45 MHz IF amplifier circuits. The first (Q2, T2, etc.) utilizes loss-less feedback to deliver reasonable gain, low-noise figure, and a high third order intercept point simultaneously. Typical gain is 10.5 dB for the first IF amplifier. There are two crystal BPFs and a second 45 MHz IF amplifier. The BPFs provide attenuation for the adjacent and alternate channels, and also for the second image response. FL1 is a four-pole crystal filter with a 20 kHz bandwidth centered at 45 MHz. FL4 is a two-pole crystal filter with a 30 kHz bandwidth centered at 45 MHz. The second 45 MHz IF amplifier provides high gain to prevent further degradation of receive sensitivity. C57, L12, C18, C19, and L13 are impedance matching elements for the input of FL1. The output of FL1 is impedance matched to the second 45-MHz IF amplifier (Q36, etc.) by C285, L64, and C242. The output of the second 45-MHz IF amplifier is impedance matched to FL4 by C287, L61, C286, C237, L60, and C235. The entire cascade provides 21 dB of gain and has a 3 dB bandwidth of 20 kHz typically. Typical insertion loss is 1.5 dB for each crystal BPF. The IF IC (U28) contains the second mixer and an IF amplifier chain. The 45 MHz IF signal enters U28 at pin 6 from the crystal BPF (FL4). FL4 is impedance matched to the IF IC input by C294, L62, and C288. The incoming 45 MHz IF signal is mixed with the second LO (to be discussed later). The second mixer IF output is at U28, pin 8 and the second IF frequency is 455 kHz. The signal from U28-8 is routed to FL3. FL3 is a ceramic BPF operating at 455 kHz. The insertion loss of the ceramic BPF is 6 dB typically in a 1500-ohm system. The 455 kHz IF signal enters U28-10, is amplified by a cascade of IF amplifiers, and exits at U28-14. The signal from U28-14 then enters a second ceramic BPF, FL2. FL2 is the final ceramic BPF with a typical insertion loss of 8 dB in a 1000-ohm system. The 455 kHz IF signal enters its final stage of amplification at U29-3. U29 is configured as a non-inverting operational amplifier and is capable of driving a 50-ohm load. The amplifier is set for a voltage gain of 2.5. With the receiver set to full gain the signal level at J4 (455 kHz IF OUT MONITOR) is -20 dBm "3 dB into 50 ohm with a -119 dBm unmodulated 136 MHz signal injected at J2 (TOP RF) or J3 (SIDE RF). The second LO consists of CR26, R33, Y1, L24, C59, C226, C227, and Q35. The oscillator is a Colpitts type with the crystal operating in the series mode. CR24 is a varactor diode used to set the oscillator on frequency using the DAC output labeled 2nd LO. The second LO operating frequency is 44.545 MHz (low-side injection). L65 and C223 impedance match the output of Q35 to the LPF (C289, C293, L63, and C284). The signal is attenuated by R282, R283, and R284 and sent on to the second mixer. The signal level at U28-4 is -16 dBm nominal. U4 is a voltage regulator used to power the receiver circuits. The dc voltage appearing at U4, pin 1, labeled RXSINK on the schematic diagram, is routed from the antenna PIN diode switch. As previously discussed, the PIN diode switch and the receiver circuits share current to reduce receive power consumption. The control line +3.3V RXEN is used to enable the regulator while the transceiver is in the receive mode of operation. The regulator is disabled during the transmit mode of operation. 2.5.2.1 Synthesizer and Reference Oscillator U19 is a fractional-N synthesizer IC programmed for a specific frequency by loading appropriate serial data into the IC. It controls the receive VCO when the transceiver is in the receive mode of operation, and the transmit VCO when in the transmit mode. The programming lines are labeled 3VSCL, 3VSDA and 3VSYNTHENA on the schematic diagram. These are all CMOS logic level inputs. R118 (RF) and R123 (RN) are the fractional compensation and phase detector current setting resistors, respectively. These resistors are critical to the operation of the synthesizer system and must be checked when troubleshooting around U19. The phase detector output pins (U19-13 and U19-14) are fed to the passive loop filter (R140, C177, C172, R134, and C173) and on to the VCO control varactor diodes (CR17/CR19) for frequency control. The buffered, filtered output from the VCO is fed into U19-5 (RF IN) to close the phase-locked-loop. The level is typically -10 dBm into U19-5. The reference oscillator is made up of CR22, Y2, Q28, C197, and C198 and associated components. The reference oscillator operates at 12.8 MHz. The reference oscillator operating frequency is adjusted by varying the dc voltage at the DAC controlled line that is labeled REFOSCMOD. This line is also used to modulate the reference oscillator during the transceiver’s transmit mode of operation. The 12.8 MHz signal is fed into the synthesizer chip at U19-8 (REF IN) using a coupling capacitor, C194. The AC signal level at U19-8 is 1V p-p typically.$

2-12 GUARDIAN VHF 110W MOBILE U22 is the reference oscillator temperature sensor used to monitor the temperature near Y2. Its output is labeled XTALTEMP on the schematic diagram. This line is normally monitored by the microprocessor so the reference oscillator can be adjusted for drift due to changes in temperature. 2.5.2.2 Receive/Transmit VCOs and Buffer Amplifiers The receive VCO operates from 181 to 219 MHz since high side LO injection is used and the first IF is 45 MHz. The transmit VCO operates from 136 to 174 MHz. Each VCO is a Colpitts type design utilizing a low noise, bipolar transistor as the active device. The receive VCO uses Q24 and the transmit VCO uses Q21, each in the common collector configuration. The Colpitts capacitors are C169/C180 (receive VCO), and C137/C142 (transmit VCO). These capacitors enable Q24 to oscillate in the 181 to 219 MHz frequency range and Q21 to oscillate in the 136 to 174 MHz frequency range. L53 is the resonating inductor for the receive VCO and L45/L46 are the resonating inductors for the transmit VCO. CR20/CR21, and CR16/CR18 are the coarse tuning varactor diodes for the receive and transmit VCO respectively. These diodes are used to coarse tune the VCO such that the LPF, phase detector output voltage (from U19) at TP10 equals 1.65 Vdc. The receive and transmit VCOs share the coarse tuning DAC controlled line labeled CTUNE. Coarse tune dc voltage swings from nominal 1.8 to 22 Vdc. CR19 (receive VCO) and CR17 (transmit VCO) are the fine-tuning varactor diodes controlled by U19 as was explained previously. CR15 is the modulation varactor diode for the transmit VCO. The output from the receive VCO is coupled off Q24-E using C174. The output from the transmit VCO is coupled off Q21-E using C139. The signal is measured at the C174/R146 node (receive) and the C139/R107 node (transmit), and measures -15 dBm typically. Q26 and Q22, and associated components, form the first VCO receive and transmit buffer amplifiers respectively. These amplifiers buffer the VCO output from changing-output voltage standing wave ratios (VSWR) that could pull the VCO off frequency. The output from each measures -5 dBm typically. The buffer is measured at the C170/R141 node (receive) and the C138/R131 node (transmit). Q25 is the second buffer amplifier. This amplifier is common to both the receive and the transmit VCOs. R131, R141, and R142 are the combining elements used to make this possible. This buffer outputs a signal large enough, after subsequent attenuation and filtering, to properly drive the RF IN pin of the synthesizer (U19-5). The output from this buffer is measured at the C167/C53/L52/C175 node and measures 0 dBm typically. The output from the Q25 buffer is filtered by C175, C53, L52, and C176. This LPF prevents the synthesizer IC (U19) from locking on to harmonics of the desired frequency. The insertion loss of the LPF is 0.4 dB typically. The signal is then split by R138, R139, and R144, and sent on to the appropriate receive or transmit final buffer amplifier. The signal measured at R139/C150/ C186 node is -6 dBm, and the signal measured at R144/R143/C168 node is -6 dBm. Q23 (receive) and Q27 (transmit) is the final buffer amplifier. Q23 amplifies the signal up to the level needed to properly drive the LO port of the DBM (discussed previously). Q27 amplifies the signal up to the level needed to properly drive the PA pre-driver (previously discussed). The signal measured at RXLO is +7 dBm typically. The signal measured at TXLO is +7 dBm typically. U17, Q20, etc. form the voltage regulator for the receive and transmit VCO/buffer amplifiers. R67, C124, and Q20 form a super filter, which attenuates voltage regulator noise that may otherwise degrade the synthesizer phase noise performance. U20, U21, Q29, Q30, CR23, CR24, CR35, C199, C202, C203, etc. create a voltage multiplier. The circuit is configured as a voltage quadrupler. Circuit losses and output loading lowers the voltage down from 24 Vdc to about 22 Vdc. The driver circuit (U21) switches at about 192 kHz. This frequency was selected so harmonics would not land at or near the second IF frequency of 455 kHz. The 22 Vdc supply is used to power the DAC supporting quad op-amp U18. The shift register (U24) is used to control transceiver modes of operation and functions. The line labeled STD/SIDE selects the desired antenna port of the transceiver. The line labeled TX/RX selects either the transmit or receive mode of operation. +3.3V RXEN turns the receiver on and off (previously discussed). Q34/Q32 and Q33/Q31 enable and disable the receive and transmit VCOs and buffers respectively (discussed previously). U16 is the voltage regulator that supplies all 5V digital circuitry on the transceiver.

GUARDIAN VHF 110W MOBILE 2-13 2.5.3 Digital/Analog Control Digital/analog control is shown on page 1 of the RECM schematic. The transceiver is fitted with an EEPROM (U15). The IC is used to store calibration and curve fit data, which is needed when the transceiver is configured with the Guardian radio. Each transceiver has its calibration and curve fit data stored within the EEPROM. The calibration and curve fit data is written to the EEPROM at the successful conclusion of level 2 testing. Two quad 8-bit serial DACs, a quad 12-bit serial DAC, and supporting operational-amplifiers (U2, U6, U13, U18, and U30) control much of the transceiver, as has been discussed previously. U32 is a 2.5 Vdc reference used by the Quad 12-bit DAC and the variable IF attenuator (discussed previously). U18D and associated components amplifies the dc signal supplied by U31-3. As was discussed previously, REFOSCMOD is the dc signal, which varies the operating frequency of the reference oscillator. Normally under DSP and microprocessor control, this line is used to FM modulate the reference oscillator, which in turn FM modulates the RF carrier in transmit mode. This line is used to temperature compensate the reference oscillator as well. The DAC controlled line TXVCOMOD at U31-4 is transmit data normally controlled by DSP and a microprocessor. This signal is routed to U18C and associated components. U18C and associated components form an active LPF/attenuator to shape the transmit data before modulating the RF carrier in the transmit mode. The cutoff frequency of the LPF occurs at 20 kHz. The 1 kHz peak-to-peak signal level at the active LPF output (U18-8) is one-fourth TXVCOMOD at 2.5 Vdc. The synthesizer reference oscillator and the transmit VCO are simultaneously modulated to balance the FM modulation. We refer to this technique as two-point modulation. The DAC values required to balance the modulation are dependent on RF frequency. The dc signal at U31-17 is routed to U30 and associated components. This op-amp is configured for a voltage gain of 2. The dc signal VATT controls the variable IF attenuator (discussed previously) in the receiver chain. Under DSP and microprocessor control, the attenuator is normally set for a desired amount of attenuation by this DAC controlled signal. Q37, Q38, Q39, Q40, Q41, and associated components are used to enable and disable the 14 dB step attenuator in the receiver chain (discussed previously). Normally under DSP and microprocessor control, the attenuator is set to the desired state of operation via U31-13. A logic level “1” at this pin enables the attenuator. Conversely, a logic level “0” at this pin disables the attenuator (bypass mode). U18B and associated components amplifies the dc signal supplied by U33-2. As discussed previously, CTUNE is the dc signal which coarse tunes the receive and transmit VCOs. Under microprocessor control, the appropriate VCO is normally coarse tuned to a desired frequency based on curve fit data stored in the EEPROM (U15). Curve fit data is obtained and stored in the EEPROM during coarse tune calibration procedures performed at level 2 testing. The DAC controlled DC signal 2nd LO sets the 2nd LO (discussed previously) on frequency at 44.545 MHz. Normally under microprocessor control, the 2nd LO is set on frequency based on a DAC value stored in the EEPROM (U15). The correct DAC value is obtained and stored in the EEPROM during the 2nd LO calibration procedure at level “2” testing. The DAC controlled dc signal RXVTF appropriately sets the varactor tuned BPF (discussed previously) based on the receiver tuned frequency. Normally under microprocessor control, the varactor tuned BPF is set based on curve fit data stored in the EEPROM (U15). The curve fit is based on statistical data obtained during the testing of hundreds of units. The DAC controlled dc signal PWRSET sets the power amplifier (discussed previously) to a desired power level. Normally under microprocessor control, the power amplifier is set to the desired level based on curve fit data stored in the EEPROM (U15). The curve fit data is obtained and stored in the EEPROM during transmit power calibration procedures at level 2 testing. The power calibration procedure obtains curve fit data for five power level settings (0.1W, 0.5W, 1.0W, 2.0W, and 5.W) over the entire transmitter operating frequency range (136 to 174 MHz). The DAC controlled dc signals PA1 and PA2 set the gate bias for each power transistor (Q6 and Q9 respectively) in the power amplifier circuit (discussed previously). These two signals are routed to op-amps U2 and U6, which are

2-14 GUARDIAN VHF 110W MOBILE configured for a voltage gain of 2. The outputs at U2-1 and U6-1, labeled PABIAS1 and PABIAS2 respectively, are then routed to the gates of the power transistors. The correct DAC values for the bias current are stored in the EEPROM (U15). The correct DAC value is obtained and stored in the EEPROM during the power amplifier bias calibration procedure at level 2 testing. Each gate is biased such that 100 mA of current flows through each power transistor with PWRSET set to a DAC value of zero in the transmit mode. Level 2 software monitors the U10 output line labeled IMONITOR when calibrating PA bias. 2.5.4 Keypad Microcontroller The keypad board is controlled by an Atmel AVR4414 microcontroller. This is a Flash programmable device. The microcontroller implements these functions:  Keypad scanning  PTT switch input  Auxiliary keys input  Volume switch input  Channel switch input  Emergency switch input  Synchronous bidirectional serial interface to main controller at 100 kHz  Keypad and LCD backlight control A clock derived from the main reference clock, clocks the keypad microcontroller at 1.5 MHz. The keypad microcontroller is powered by the 3.3V supply as the LCD driver device. 2.6 Audio Amplifier Board 2.6.1 Description The Audio amplifier board contains the internal and external audio and control circuitry. It also houses the DB25 accessory connector, the DB9 power connector, and the RF control connector that protrudes through the rear panel. The board is located in the Control Module. The board contains the following functions:  RFI and transient protection and system on/off switch  Voltage regulator and 7.8V on/off switch  Communication with transceiver  Audio power amplifiers  Power levels detector and converter and the RF and DC combiner  PA on off control  RFI and transient protection 2.6.2 Power Conditioning Power for the Guardian 110W control head enters this board on J5 the DB9 connector. Dual low RDS(on) P-channel FET Q10 serves as reverse polarity protection and on-off switching. Transistor Q7 pulls down the gates of Q10 when the ON/OFF signal is high, allowing Q10 to conduct. With ON/OFF control low, Q10 is cut off, and will not pass forward or reverse polarity. An over-voltage condition is detected by D2 and Q6, which cause Q7 to cut off and turn off power. Back-to-back transorbers D1 and D4 are used to eliminate voltage spikes before the on/off switch. The input power is routed to the clamp circuit via an LC filter. The filter eliminates unwanted signals from being conducted to the vehicle power line.

GUARDIAN VHF 110W MOBILE 2-15 2.6.2.1 Voltage Regulator and 7.8V On/Off Switch Linear regulator U5 provides +7.8V to the RF power control circuitry and to the other two PC assemblies in the control head. The regulator is powered via Q10 body diode at all time. When the unit is turned off all the circuits are disconnected from power except the transceiver in the control head. The transceiver in this case is in the off state. The power consumption in this case is less than 2 mA powering the boat backup memory circuits. 2.6.3 Communication with Transceiver Twenty pin IDC headers J2 and J3 carry control and status signals from the transceiver and front panel via the Control PCA. 2.6.4 Audio Amplifiers The board contains two identical audio amplifiers. Each audio amplifier has 20 dB gain and is capable of delivering more than 10W to a 4-ohm load in a bridge-tied-load configuration. They are fed from the transceiver audio output. A front panel switch selects either or both amplifiers; an unselected amplifier is placed in a mute condition by the appropriate disable signal. When there is no received signal, both amplifiers are placed in a low-current standby mode by squelch comparator. 2.6.5 Power Levels Detector, Converter, and RF/DC Combiner ON /OFF, PTT and RF output power control signals to the 110W power amplifier are generated on this board. These are present as DC signals on the center conductor of the coaxial cable connecting the control head to the remote RF PA. A low-pass filter prevents RF from reaching the control circuitry. The voltage levels are as follows: DC Control Voltage Range PA State 0 to 0.4V DC on/off switch – OFF >0.7V DC on/off switch – ON 0.7 to 1.2V PA is in bypass – RECEIVE mode 2.1V Power output set 25W 3.6V Power output set 50W 6.5V Power output set to 110W The transceiver power levels are detected via the connection to TP21. The voltages are as follows: TP 21 Control Voltage Boat Power Output 2.85 5W 1.87 2W 1.28 1W The control circuits converts an input above 2.2V (5W setting) to a control signal to 6.5V, which results in 110W generated in the remote RF power module. Accordingly it converts the 2W and 1W control levels to the indicated PA control. Input control of less than 1V is converted to 2.6V. The PA puts out 25W also for the 0.5W input power setting but will fail to do so at the 0.1W setting. In this case power output is not specified, and the red LED will not light.

2-16 GUARDIAN VHF 110W MOBILE 2.6.6 PA ON/OFF Control (Bypass Mode) It is possible to operate the system not utilizing the PA (PA in by pass mode.) This is done by turning on control head on with the PTT depressed. An orange TX light indicates to the user that he is operating in by pass mode. In this mode, output power is about 1dB lower that the nominal levels delivered from the transceiver, as indicated in the table above. In normal mode, Q16 conducts at start-up, causing Q14 to conduct, which keeps Q15 off. When using this mode, Q16 conducts in the reverse direction, Q14 remains off and Q15 conducts, which prevents bias voltage from being sent to the RF power amplifier. 2.6.7 RF Power Indication Operational amplifier U3A forces the output control voltage at Q8-E to be equal to that at U3-3. After high power transmit is detected at the PA output. The RF PA test circuit forces additional current back into this line. The op-amp loop holds the voltage at the input level, so the additional current is forced out Q8-C and through R44. This forces Q9 to conduct and sink additional current from the LED_TX. The LED_TX turns off the green light. When the unit is in bypass (low power) mode the Tx lamplights orange because the red and the green LED’s are on. 2.6.8 Audio Board Block Diagram Audio Block diagramRFI filter&transientprotectionon off switch voltageragulator7.8volts 7.8voltsswitched internalaudio amplifierexternalaudio amplifieraudio inpower levelvoltageconverterRF&DCcombinerRF INRF &control out/inDB9DB25J2 - IDC 20 pin J3 - IDC 20 pinPA on offcontrolSwitch PTT7.8voltsswitchedinput voltageaudio out paudio out naudio out paudio out nj4power level input Figure 2-4: Audio Board Block Diagram

GUARDIAN VHF 110W MOBILE 2-17 2.7 Display Board The Display board consists of a seven-switch keypad and an LCD module with integrated LED blue backlight. The board is heatstaked onto the plastic front panel, forming a permanent assembly. Electrical connections are made to the Interface board via a 20-pin connector (J13). The radio display module is a full graphics 80x32 pixels LCD, requiring a temperature compensated differential driving voltage of about 12V and a 1/6 bias, 1/32 duty cycle driving scheme. The LCD driver device (Seiko Epson SED 1530) drives the display. This LCD driver has an internal display RAM that copes with all the display refreshing autonomously. Display data transfers from the main controller are only required when the display is changed, selective display RAM updates are also available to minimize serial traffic. The LCD driver display RAM is accessed through a one way synchronous serial interface and connected in parallel with the AVR serial port. The LCD CS input is used to differentiate between serial data for the LCD driver and the keypad board hardware reset line resets the display drive. The hardware is configured such that during hardware reset, before serial LCD data is presented, the LCD is blank. The radio keypad consists of 16 keys, which contact onto switch contacts on the rear of the keypad board. Keypad Figure 2-5: Keypad Board

$2-18 GUARDIAN VHF 110W MOBILE 2.7.1 Control Logic Interface The signals on this interface need not be filtered, but are protected from short circuits to ground. All logic signals are at 0 to 3V Complimentary Metal-Oxide Semiconductor (CMOS) levels at the interface. The interface carries the following functions: • 10V Control • Ground • /RADON • Switched 10V Supply • Reset • AVR Clock • Serial Data Clock • Serial Data Input • Serial Data Output • Key Interrupt • LCD Chip Select • LCD A0 (data\command select) • Keypad Chip Select 2.7.2 Keypad 2.7.3 Switch Interface Interface to switches is provided to the RECM via 80-pin connector to the Interface board. 2.8 Interface Board This board is located in the Control Head Assembly in the vehicle cab. The transceiver (RECM) is mounted to this board and interfaces through 80-pin connector J1. The front panel display PCA mounts to this assembly and interfaces through 20-pin connector J4. The microphone interface is J5, an 8-pin modular connector. Communication with the audio amplifier board and the remote RF Power Amplifier is through two 20-pin connectors J2 and J3. The DC power for this board, the transceiver and front panel functions enters via J3. The 3.3V powering the display and logic is generated by a linear regulator U1 powered from the 7.8V via an on/off switch q12. All front panel switches and LED lamps are mounted to this board. Connection to the internal 5W speaker is via J6. ON/OFF control: Transistors Q11-14 are connected to the outputs of the binary volume switch SW3. The transceiver uses these signals to detect the off position of the volume switch. At the off position all lines are open. If any of the lines is switched and ignition power is high Q17 is on providing low (0V) to one of the transistor witch will result in a positive ON/OFF voltage. This signal witch is routed also to the audio board to control power function there and in the remote RF Power Amplifier. SW4: Used to change channels. The transceiver uses the binary outputs to detect the position of the channel switch. Toggle Switches: Program switch SW1 for a variety of functions. Switch SW2 is used to select between internal and external audio speakers. Front panel buttons: Keypad depressions on the front panel are detected by the scanning outputs from the transceiver. Keypad depressions on the optional DTMF microphone are detected by the DTMF decoder on this board and are processed as ordinary scan-in signals by the transceiver. DTMF keypad processing: The optional DTMF can be used to program the radio. Keypad depressions generate a DTMF tone in the audio output. This signal is routed to DTMF detector U6, and digital outputs are sent to1-of-16 de-multiplexer U2. The outputs from U2 are used to control analog switches U3-5. In this way the transceiver scan-out lines can be connected to the appropriate scan-in lines to simulate a physical switch closure.$

GUARDIAN VHF 110W MOBILE 2-19 PTT processing: In normal operation, a PTT switch closure causes Q2 to conduct, which in turn causes Q7 to conduct. This signal is distributed to the rest of the radio as the PTT signal. When a DTMF button is depressed, the transceiver automatically transmits this tone. PTT lockout: To prevent transmission of DTMF tone during programming, a latch circuit is provided to lockout PTT. When the ENTER button is pressed the PTT signals is disabled by a latches circuit. When the ESCAPE button is pressed the lockout latch is reset. It is recommended to utilize the PTT condition lockout during programming the PTT (light will stay off). This is done by pressing ENTER key and after that hold the PTT key depressed until programming is done. To re-key the radio release PTT and key the radio once the radio is out of the programming mode use the ESC key quit programming. J1, 80-pin boat connectionJ2, IDC, 20-pin audioconnectionJ3, IDC, 20-pin audioconnectionJ4, 20-pin displayconnectionJ5, RJ11, 8-pin MICand KLV connectionDTMF to keypadinterfaceProgramming PTTdisableVolume selectorand on/off controlOn/off controlled3.3V regulatorLEDdrivers/controlChannel, speakerout, ABC switchselectors J6, 2-pinspeakerconnection Figure 2-5: Interface Board

GUARDIAN VHF 110W MOBILE 3-1 CHAPTER 3: SOFTWARE THEORY OF OPERATION 3.1 Functional System Operation 3.1.1 General All control and channel software is resident in the RECM. 3.1.2 Guardian Block Diagram Figure 3-1: Software Theory of Operation Block Diagram Switches LCD Keypad Keypad MPU H8 Controller DSP AudioDB25 Accessory Connector Transceiver PSUPower Supply External PowerReceiver/Exciter/Control Module (RECM) BatteryDataPowerModulation Control IF Output Control/Fill/Code Keyfill User Data

3-2 GUARDIAN VHF 110W MOBILE 3.1.3 Architecture A single digital signal processor (DSP) handles all signal-processing functions. An H8 microcontroller is used to control the user interface and implement other radio control functions. All references to signal names relate to the Receiver/Exciter/Control Module (RECM). Functionality partitioning is shown in Figure 1-1. 3.1.4 Board Identification The control logic stores an electronic serial number and modification status within nonvolatile storage on the board. 3.1.5 Self-Test on Power-Up The software automatically executes a self-test when the radio is switched on. This test is capable of detecting and identifying faults that prevent the radio from properly operating. 3.1.6 Flash Software Upgrades The radio software is updated if required using a PC and the Guardian G25AXG004 PC Programming/Cloning cable. 3.1.7 Voice Coder/Decoder (VOCODER) The VOCODER uses an improved multi-band excitation (IMBE) voice-coding algorithm as specified in the telecommunications industry association and electronic industries alliance (TIA/EIA)-102.BABA. The IMBE VOCODER compresses a high-bit-rate waveform into a low-bit-rate data stream suitable for transmission over the channel. The VOCODER operates at a net bit rate of 4.4 kbps for voice information and a gross bit rate of 7.2 kbps after error control coding. 3.2 Radio Control Software This software controls the transceiver and baseband signal processing functions. 3.2.1 Audio Control H8 controls the analog audio signal processing. Audio for transmission comes via an external microphone attached to the front panel. It is wired into the microphone amplifier, which is permanently powered. Audio output is required when a voice message is received or a tone is generated by the user interface. To allow audio output, H8 sets either SPKRON or EXTSPKRON to the internal speaker or the accessory connector. If an external audio accessory is detected by who are you (WRU) <0.5 Vdc, the audio is routed to the accessory connector. Otherwise audio is routed to the internal speaker. The 16-position volume control knob is decoded and sent to the DSP through the controller software to control the output audio volume. 3.2.2 DSP Control Software The DSP implements most of the baseband signal processing in the radio. Its function is controlled through its host port by the H8 controller. The DSP operates in a number of basic modes controlled by H8 through the host port. They are as follows: Mode Description Idle Current shutdown mode released through the host port Searching Actively looking for a signal on the IF input signal Searching paused Search algorithm paused for an economize cycle or frequency change Active receive Actively receiving a message, initiated by detecting a signal or H8 command Transmit Actively transmitting voice or data Keyfill Keyfill operations and key Management Management tasks

GUARDIAN VHF 110W MOBILE 3-3 The DSP pages-in different program images from the Flash for different modes of operation. Typically one image is used for receive and standby modes, but a new image is needed for transmit and key management operations. The DSP can interrupt the H8 controller, and then pass data over the host port back to H8. Interrupts from the DSP include the following events: • Signal detected with type data • Signal lost • DSP BIT errors • Paging request In all active modes the H8 software must be able to write a number of parameters to the DSP and also read back a number of parameters from the DSP. This is implemented through the host port. The parameters used include: Mode Description Search Reference oscillator temperature used by DSP to correct frequency offsets. AGC reset control is used at start of search period Analog setting BW, squelch tones, squelch code, and squelch level Digital setting Data rate, key, and algorithm Project 25 setting NAC and TGID CVSD setting Continuously variable slope delta (CVSD). Data rate Receive Reference oscillator temperature used by DSP to correct frequency offsets. Audio volume Analog setting Squelch controls, de-emphasis, and companding Digital setting Data rate and key algorithm Project 25 setting NAC, TGID, BER, and test mode CVSD setting Data rate and key Project 25 setting Read by H8: SS bits, low-rate data (for future use), and sender ID Transmit Reference oscillator temperature used by DSP to correct frequency offsets. Audio volume, sidetone on/off Analog setting Squelch controls and de-emphasis CVSD setting Data rate and key Project 25 setting NAC, TGID, key and low-rate data (for future use) 3.2.3 Transceiver Board The Transceiver board is controlled through a synchronous serial bus from H8 to the transceiver allowing H8 to control the synthesizer, two 4-channel 8-bit digital to analog converters (DAC), and a control shift register in the transceiver board. Some of the DAC channels are set according to data in the transceiver’s electronically erasable read-only memory (EEPROM) calibration tables. 3.2.3.1 Mode Control The transceiver shift register and the CTX output of the field-programmable gate array (FPGA) control the modes of operation (transmit, receive, or standby). The outputs are controlled as below: Mode Description Spare (SR bit 1) Spare 3.3VRXSynth (SR bit 2) Set in active receive mode, RXVCO enable 3.3VTXSynth (SR bit 3) Set in active transmit mode, TXVCO enable 3.3VRXEnable (SR bit 4) Set in active receive mode, receiver enable Spare (SR bit 5) Spare Spare (SR bit 6) Spare

3-4 GUARDIAN VHF 110W MOBILE Mode Description TX/RX (SR bit 7) Set in active transmit mode, front end TX/RX control STD/SIDE (SR bit 8) Set to use radio antenna, reset to use accessory connector RF port CTX (FPGA output) Set in active transmit mode to enable the RF power amplifier 3.2.3.2 Frequency Control The frequency of operation in both transmit and receive is controlled by the H8 setting in the synthesizer through the serial bus. To set the desired frequency, the appropriate TX or RX synthesizer enable S-R bit must be set, the serial data loaded into the synthesizer chip, and the DAC2 output A synthesizer coarse tune set to the appropriate value for the frequency according to the EEPROM calibration table. Synthesizer lock is monitored by the out-of-lock (OOL) input. Once the synthesizer lock is achieved, the transmitter or receiver is enabled with the appropriate control bits 3.3VRX enable, CTX, and TX/RX. Economizing the synthesizer function is implemented by controlling the 3.3VTXS/RXS bits and by controlling the EM main divider enable bit in the synthesizer control word. If the frequency is unchanged, the synthesizer serial data need not be reloaded when coming out of economize. 3.2.3.3 12-Bit DAC DACLDA, DACADCCLK, and DACDOUT control the 12-bit DAC for IFAGC, TXVCOMOD, REFOSCMOD, and VATT. 3.2.3.4 Reference Oscillator Temperature Compensation The H8 software constantly monitors the reference oscillator crystal temperature using the XTALMON line. The temperature data is used to lookup the compensation factor in the transceiver’s EEPROM calibration table. This compensation factor is written into the DSP, added as a dc offset reference oscillator modulation signal, and used as a dc offset in receive mode. 3.2.3.5 Receiver Control Setting 3.3VRXE enables the linear receiver chain. The DSP implements software AGC system to control the gain of the linear receiver chain. The H8 controller monitors the actual received signal level by reading RSSI. At all times during receive the RXVTF DAC2 output C must be set to the value in the EEPROM calibration table corresponding to the receive frequency used. This makes the receiver’s front-end tunable filter centered on the desired frequency. At all times in receive modes the second LO DAC2 line output B must be controlled using data from the EEPROM calibration table and indexed with oscillator temperature data XTALMON. The temperature compensates the second LO in the receiver chain. 3.2.3.6 Transmitter Control The radio uses a complex H8 software-based algorithm to dynamically control the transmit power of the radio. The inputs to the power control algorithm are: requested power level (0.1W, 0.5W, 1W, 2W, or 5W), PA calibration data in the EEPROM, supply voltage BATMON (used for monitoring), transmit frequency, PA current, (used for monitoring), and PA temperature (used for monitoring). The power control algorithm takes these inputs and uses them to control the following outputs to provide a steady RF power output with a clean rise and fall at switch on/off. Output Description PWRSET (DAC1 output A) Sets the power level in the power amplifier ALC loop PABIAS1 (DAC1 output B) Adjusts the bias in the final driver stage PABIAS2 (DAC1 output C) Adjusts the bias in the final driver stage 3.2.3.7 TX/RX Switching The procedure needed to quickly switch the transceiver from receive to transmit and back again is to shut down the current mode, lock the synthesizer in the new mode on the new frequency, and enable the transmitter or receiver, as required.

GUARDIAN VHF 110W MOBILE 3-5 3.2.3.8 Receiver Scanning In some scanning modes it is necessary for the radio to scan a number of channels looking for traffic, as controlled by the H8 software. The basic requirement is to change the synthesizer frequency, RXVTF, synthesizer tune DAC, and to resume searching on the new frequency. The DSP may have to be informed of new traffic settings on which to search, for each new frequency. Scanning is interrupted when the DSP detects a signal of interest. 3.2.4 DC Power Control The H8 controller software controls the power supply switching in the radio. The control software algorithm uses the following inputs: Input Description /PWROFF Indicates the current position of the radio on/off switch and the accessory connector off line WRU Indicates if the radio is fitted into a harness providing external power /LBOUT Indicates the supply voltage is at the minimum required for correct operation BATBUS Not used in the mobile configuration BATMON Indicates the voltage on the main radio supply from external power source These inputs are used to control the following FPGA outputs: Output Description PWRHOLD Set during normal operation, the radio stays on regardless of the on/off switch. When PWROFF indicates that a switch off is required, software shut down is executed followed by a release of this output BATOFF Not used in the mobile configuration Additionally the /LBOUT interrupt is used to execute a fast shutdown of the software when the supply voltage drops below that needed for normal operation, or when the power source is removed without switching the radio off. 3.2.4.1 Power Supply Frequency Control The power supply software controls the switch mode power supply frequency output according to the RF frequency used. The frequency is checked and changed if necessary at every synthesizer frequency change. 3.2.5 Monitoring The H8 software monitors the following signals: Signal Description Out-of-lock In all active modes, every 100 ms EPTT/RTS In all modes, every 20 ms RSSI In receive modes, every 100 ms WRU In all modes, every second DC voltage In all modes, every 5 seconds PA temp In transmit modes, every second REF temp In all modes, every 5 seconds PA current In transmit modes, every second 3.2.6 Radio Control Drivers A number of low-level software drivers are used by H8, which interface to the transceiver hardware.

3-6 GUARDIAN VHF 110W MOBILE 3.2.6.1 Audio and Power Supply Unit (PSU) Driver A serial interface driver controls the output bits of a serial-to-parallel output shift register in the FPGA. Clock and data source for this shift register is the same serial port used for the user interface serial bus, but data is directed to the shift register using high-order H8 address lines. 3.2.6.2 Transceiver Serial Bus Driver A serial interface driver controls the transceiver shift register, DAC, and synthesizer. It uses a common clock and data line, and three separate strobe lines for each device. 3.2.6.3 DSP Host Driver The H8 software includes a DSP host driver for controlling the DSP mode of operation, and initial start-up code download. 3.2.6.4 IIC Bus Driver The H8 software includes a driver that allows the controller software to read and write to the transceiver EEPROM using IIC protocols. The two lines are general-purpose I/O lines controlled on a bit-by-bit basis by the software. 3.3 Digital Signal Processing The DSP software implements all baseband signals processing in the radio. It processes signals between the user audio and data interface, and the transceiver modulation and intermediate frequency (IF) interfaces. The signal processing provides compatible analog FM modes, common air interface (CAI) compatible modes, and 12 kbps secure CVSD modes. 3.3.1 DSP Transmit Chain Signal processing while the radio is transmitting depends on the radio's operational mode. The possible modes are clear analog voice FM, CVSD DES voice, Project 25 clear digital voice, and Project 25 DES digital voice. The Transmit DSP Chain block diagram is shown in Figure 3-2. The major signal processing functions of the DSP transmit chain are described in the following paragraphs. 3.3.1.1 Audio Coder/Decoder (CODEC) The Guardian uses a Texas Instruments® TLV320-AC36 audio CODEC. Data is transferred to and from the CODEC using the DSP enhanced synchronous serial interface (ESSI) 0 port. The data word is 16 bits long. The first thirteen bits are the two’s compliment audio sample, and the last 3 are the volume control word in the receive direction (DIN), and zero padded in the transmit direction (DOUT). The DSP currently sets volume control bits for no attenuation. Scaling the signal prior to sending it to the CODEC controls the volume. The sample rate from the CODEC is 8 ksps. 3.3.1.2 Audio Processing Board The Audio Processing board receives audio input from the audio CODEC, applies filtering and automatic gain control (AGC), and transmits it to the mode-specific formatting module. The audio filter has a passband from 300 Hz to 3 kHz. This board also transmits DTMF tones to the audio CODEC. DTMF over-dial is supported to allow redirection through the phone network via a base station. Data is transferred to and from the CODEC under interrupt service routine (ISR) control. 3.3.1.3 Project 25 Voice Module The Project 25 Voice module performs framing and conversion tasks. The framing function uses its own task table to build a CAI time-division multiple access (TDMA) frame. This includes compression of the voice signal using the IMBE VOCODER, forward error correction, and encryption. The physical layer task converts a 4.8 ksps dibit data stream into a 48 ksps real sampled waveform, which is then fed to the Modulation module. The physical layer scales each dibit symbol so that the proper frequency deviation is attained. It applies raised cosine filtering for control of inter-symbol interference.

$GUARDIAN VHF 110W MOBILE 3-7 Figure 3-2: Transmit DSP Chain 3.3.1.4 CVSD DES Module Audio data from the Audio Processing module is sent to the audio circular buffer. The sample rate is increased from 8 ksps to 12 ksps. The CVSD encodes the data and sends it to the transmit CVSD audio circular buffer. The data is DES-encrypted and differentially encoded before sent to the physical interface buffer. The CVSD physical layer converts the CVSD encoded, DES encrypted 12 ksps data stream into a 48 ksps waveform suitable for processing by the Modulation module. The module contains a finite impulse response (FIR) raised cosine filter that acts as an interpolation filter. Transmitting an end of message (EOM) indicator, consisting of 160 ms of alternating ones and zeros, signals the end of a transmission. This allows the receiving radio to squelch the audio output before the radio stops transmitting. 3.3.1.5 Analog FM Module Audio data entering the Analog FM module is sent through a linear-phase, FIR, audio-shaping filter. Interpolation from 8 ksps to 48 ksps is accomplished using a linear-phase, FIR filter. A single-quadrant sine look-up table (LUT), using fractional addressing and quadrant folding, generates continuous tone controlled squelch system (CTCSS) tones. If the DCS audio turn-off code is transmitted, the tone is fixed at 134.4 Hz and the codes transmitted at a rate of 134.4 bps, derived using the CTCSS tone generator. The DCS data stream passes through a raised cosine filter before added to the speech. The 8 ksps audio stream, with CTCSS/DCS controls, is interpolated to 48 ksps before sent to the Modulation module. 3.3.1.6 Modulation Module The Modulation module prepares the signal for transmission. The signal is split into a reference oscillator signal and a voltage controlled oscillator (VCO) signal. This allows independent scale and offset values for each signal. A modulation-balance variable scales the reference oscillator voltage, so that the maximum frequency deviation is constant for all RF channels. A transmit modulation variable does the same for the VCO signal. CVSD DESModuleAudioCODECTransceiverAudioProcessingModuleModulationModuleProject 25 VoiceModuleAnalog FMModuleVOICEDTMFTones$

$3-8 GUARDIAN VHF 110W MOBILE 3.3.1.7 Transceiver Interface The transceiver DAC has four output ports, two of which modulate the carrier. One of the two channels maintains carrier frequency accuracy. On transmit channel changes, the controller provides the DSP with two fractional values used to scale the two signals output from the DAC. The controller provides the DSP with an additional integer value at one second intervals, and is added to one of the DAC output signals to control carrier frequency accuracy. The modulation interface receives modulation data samples at 48 ksps, independent of the transmit mode. When the radio is operating as a transmitter, the transceiver interface controls the operation of the DAC via ESSI 1 on the DSP. Data is written to the DAC at 96 ksps. 3.3.2 DSP Receive Chain The radio receive chain hardware consists of an RF transceiver board, analog to digital converter (ADC), a Motorola® DSP 56302 or DSP 56309, and an audio CODEC. The Receive DSP Chain block diagram is shown in Figure 1-3. The major signal receive functions of the DSP receive chain are described in the following paragraphs. Figure 3-3: Receive DSP Chain 3.3.2.1 Transceiver The RF transceiver board performs mixing and filtering of the received signal to produce a 455 kHz, 25 kHz bandwidth (BW), IF signal. The output signal from the transceiver is digitized by the ADC and fed to the DSP. The bulk of signal processing is performed by the DSP. An ISR that implements the transceiver/ADC/DAC interface is called at a rate of 96 kHz in receive modes. The ISR reads ADC output data, stores the values in a circular buffer, and controls data transmission to the DAC. 3.3.2.2 FM Demodulator The FM demodulator converts the FM output of the transceiver to a real-valued, baseband signal. FM demodulation is implemented by a discriminator task. Sub-sampling the 455 kHz IF at 96 kHz folds down the signal to 25 kHz. A mixing function mixes the sampled IF data in the input buffer before filtering. For 12.5 kHz channels, a second CVSD DES Module Audio CODEC Transceiver Audio Processing Module FM Demodulator Project 25 Voice Module Analog FM Module Signal Detectors$