Hitachi Kokusai Electric America AT75000 5000W UHF ATSC Transmitter User Manual AT75K0 1 Owner s Manual
Hitachi Kokusai Electric America LTD 5000W UHF ATSC Transmitter AT75K0 1 Owner s Manual
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![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 31/139 2.9 Installing Exciter / Driver into a transmitter For the installation of the exciter driver into a transmitter the following conditions are necessary: 1- Two samples of feedback (before and after the filter). The amplitude/frequency response should have less than 1dB of ripple within +/- 15MHz of the channel of operation. 2- Impedance of the sample ports must be 50 ohms 3- The RF level of the sample before and after the filter must be between -10dBm and 0dBm (average level). When the exciter / driver RF output is connected correctly to the transmitter pre-amplifier and the correct RF level samples before and after the output RF mask filter are connected to the applicable sample input ports, the operator can then use the GUI7001 software (optional) to make linear and nonlinear pre-corrections and the performance measurements 2.10 Possible operations with the exciter / driver Below are the possible operations of the exciter driver available when installed in a transmitter. A- Power adjustment – POWER SETUP ([1100]) Power adjustment of the exciter driver which may* alter the transmitter output power is possible and accessible through the POWER SETUP screen ([1100]) and accessed from the Main Menu for the Menu on the display digital. Instructions are given in the annex (Operational Software). It is important to note that if the power of the transmitter is altered the modulation level and consequently the non-linear distortion will change which will require the pre-correction to be recalculated. This can be done through the SCALE adjustment ([1520]). The recalculation of the correction must be done after all final power level changes. For best results and the software GUI7001 (optional) for performance measurements should be used. * Note that some transmitters may have an ALC around the pre-amplifier or final amplifier or combination thereof, which will disenable any power adjustment from the exciter. B- Pre-correction of transmitter The corrections for linear and non linear distortion will have been tested and temporarily set up in the factory for typical operational characteristics. When installed into a transmitter, if there is significant change in the RF output characteristics of linear and nonlinear distortions, thus affecting its frequency response, group delay and levels of inter-modulation, is suggested to carry through a new process of pre-correction of the transmitter. This process can be made through optional GUI7001 Software (Optional). D- SCALE adjustment This parameter adjusts the amount of non-linear pre-correction being a applied to the signal. The inter-modulation of the signal varies with the power output. This “scale” adjustment can be used to optimize the levels of shoulder without the need to recalculate the pre-correction curves using software GUI7001 (optional). The value of this adjustment must be proportionally reduced when the transmitter output power is reduced.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-31.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 49/139 PFC The PFC circuit is located at the PC Board CIP8467, MODULE – 4580. This circuit is composed by a power supply with a boost regulator on continuous conduction mode (CMM). This arrangement guarantees power fact better than 0.9 [cos > 0.9]. Using bridge of diodes, a full wave rectification and a boost inductor the low voltage is elevated up to +375V. The power factor correction is achieved via a switched MOSFET transistor controlling the AC current on the rectified filter capacitors. The switching frequency is 100 kHz. PFC Control The PFC circuit is pulse-controlled. The pulse stream is generated on the CIP8439. This control is implemented via an integrated circuit that is self-protect against short-circuit and two extra feedback circuits for safety. This arrangement is implemented to guarantee a highly stale +375V voltage present on the output of the PFC circuit. Full Bridge The full bridge circuit is also located at the PC Board CIP8467 - module 4580. This circuit converts the +375V down to +42V with high current rate. To be able to deliver high power this circuit uses a full bridge topology, with four IGBT (Isolated Bipolar Gate Transistor) transistors connected on pairs. The +375V is routed to the IGBT devices. These devices are switched at frequency of 25 kHz. The switching pulses are connected to a transformer reducing the voltage, and in sequence the rectification, filtering generating than the +42V. Power for the Controls and +15V Output The PC Board CIP8467 also includes a circuit that delivery power for the PFC and Full Bridge Controls. Out from this same circuit it is extracted the +15V voltage that power exclusively the digital control unit PC Board CIP8448. This +15V power supply, is a linear power supply. A step down transformer drops the 208V out from the main line followed the diode wave-rectification and ripple filtering. Two voltage are extracted from this power supply, +15V and +18V. The +18V power the PFC control board, and the +15V power the Full Bridge control circuit and the digital control unit, PC BoardCIP8448. NOTE: These 2 voltages, +15V and +18V do not share the same ground circuit. They do have separated grounding. (isolation 3kV). Full Bridge Control and Voltage Reading/ Output Current Reading The module 4580 includes a PC Board 8444. This PC Board generates the control pulses for the Full Bridge controlling. On this same PC Board is located a TRIMPOT, TPO-1, to adjust the output +42V voltage. The TRIMPOT TPO-2 performs the setting for protection against over-current. The TRIMPOT TPO-3 perform the reading adjustment for the output voltage, this information is routed to the digital control unit PC Board CIP8448. Also on this PC Board are present the circuits for current readings, totaling 10 independent readings. The trim pots TPO-4 up to TPO-13 are adjusted or the proper reading. See the table below:](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-49.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 61/139 Forw. Power: Shows the forward power value in watts generated by the drawer. Refl. Power: Shows the reflected power value in watts generated by the drawer. Voltage: Shows the voltage value in volts generated by the drawer power supply. Software: Shows the name and the version of the system software of the control drawer. This information is made of three parts: module identification, numeric identification of the software and version indication. The following identifications are possible: ATXXXX 0.0 for the equipment of the Advanced TV line with ATSC standard, Such identifications must be provided to Linear in case of the need for maintenance or information about the equipment. ATTENTION Any test, maintenance and operation procedures in Linear equipment must be performed by authorized personnel that are trained in transmission equipment for TV signals or by personnel trained in Linear equipment. In case of doubt, contact Linear. VGS Started: Indicates if the transistors VGS voltages in the power module were started when the drawer is on. VGS Start Fail: Indicates if the VGS voltage of any of the transistors were not correctly started. Also, it can indicate a problem in the current communication system between the control system and the transistors. VGS Timer: Indicates the time elapsed during the tests for the assessment of tables of quiescent current correction coefficient by the temperature. The normal value is 00:00:00 during the normal operation of the drawer. The value of the time lapsed in the test is indicated only after the test is completed. When the drawer is turned off, the value of the time elapsed reverts back to 00:00:00. Drawer Model: Shows the numeric identification code for the drawer model. Such identification must be provided to Linear in case of the need for maintenance or information about the equipment. ATTENTION Any test, maintenance and operation procedures in Linear equipment must be performed by authorized personnel that are trained in transmission equipment for TV signals or by personnel trained in Linear equipment. In case of doubt, contact Linear. 42V S.D.T.: 42 Volt Shut Down Timers: Show time elapsed during the powering off cycles of the 42V power supply. If a first powering off occurs, timer 1[00:00] is started and shut down in 30 seconds. If a second](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-61.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 62/139 powering off occurs, timer 2[00:00] is started and shut down in 60 seconds. If a third powering off occurs, timer 3[00:00] is started and shut down in 120 seconds. During each of these shut down counts, the power supply remains powered off. The powering off might be caused by reflected power alarms, temperature outside the limits or current outside the limits. If during any shut down counts the alarms state are resolved, the shut down counts continue until the end with the power supply turned off. At the end of the shut down counting, the power supply is turned back on and kept that way if there are no more alarms. Also, each time the power is turned back on, the timer 4[00:00] is started and shut down after 10 minutes. If after 10 minutes there are no new alarms, all four timers go back to zero. If there is a re-incidence of the alarms, the next timer is activated. If all three timers reach their maximum value the power supply is powered off permanently. The timer values and the alarms that caused the powering off are logged at the non-volatile memory of the control system and they can be accessed for diagnostic purposes. To erase the timer values of the non-volatile memory, one must access option (6) Alarm Logs. Below there is a graphic that shows how these timers work: 42V Shut Down Counter: Shows the number of times that the power supply was turned off. Its value is logged at the non-volatile memory of the control system. To erase the value of the timer, one must access option (6) Alarm Logs. [Form: C]: Shows which configuration of the RF sum, the power drawer operates. If the power drawer operates in large equipment, this drawer will have its RF output added (combined) to the output of the other drawers, what is indicated by the letter “C”, for Combined. In case this drawer operates in a mid size equipment (just one power drawer), its signal is not added to the signal of other drawers and its configuration is called Single, “S”. This indicator is configured by the control drawer of the equipment, or by accessing the HyperTerminal during special test conditions. For each option mentioned the alarm system deals with the occurrences differently. For option C, the current alarms, temperature and reflected power can turn off the](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-62.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 66/139 NM: This indicator shows the quiescent current adjustment coefficients per temperature calculation screen. If the calculation is started with the drawer outside the transmission rack, it won‟t be possible to identify the number of the drawer and save it at the non-volatile memory. In this situation, the information saved is the indicator NM which means “Power Drawer Number Not Memorized”. If the calculations are done with the drawers in the transmission rack and the address connectors RS485 turned on in the drawers, the drawer number is saved in the memory. This way it is possible to connect the boards with the control system (microprocessor boards) to the respective drawers by their identification numbers, because, after the calculation is done, the coefficients saved only work with precision in the drawer where they were calculated. In other words, after the calculation, it is not possible to swap control boards. More details can be seen in the item that deals with the calculation of those coefficients. ATTENTION Any test, maintenance and operation procedures in Linear equipment must be performed by authorized personnel that are trained in transmission equipment for TV signals or by personnel trained in Linear equipment. In case of doubt, contact Linear. It is possible to display 32 alarms at any one time, both current and old. However, not all 32 alarms are activated and some are reserved for future use. Below are the description of each alarm and a layout of the power drawer to facilitate diagnostics and module identification. Right after the drawing is a table with conditions and measurement values that activate alarms and shut down the power supply. In the time diagram, at the end of the manual, there is the verification frequency in seconds [s] for the alarms and other information. When it is noted that a shutdown of the power supply occurred, it always occurs as described in the 42V S.D.T. function, explained in detail on Item 5. 1) Fan F!: Occurs when all the fans stop working at the same time. In this case, the fuse that protects all fans might be open. This fuse is located inside the drawer‟s power supply. The drawer has three banks of 4 fans. If in one bank only one fan fails, the entire bank is considered faulty, even if the remaining three 3 fans are still working. If any fault occurs in all three banks at the same time, this alarm is activated. This alarm doesn‟t cause the power supply to shut down. If there is a fault in the fan system, a sequential shut down is activated because of the increase in temperature. 2) Temp1!: Occurs when the power module temperature M1 is greater than 72º C. 3) Temp2!: Occurs when the power module temperature M2 is greater than 72º C. 4) Temp3!: Occurs when the power module temperature M3 is greater than 72º C. 5) Temp4!: Occurs when the power module temperature M4 is greater than 72º C. 6) Temp5!: Occurs when the power module temperature M5 is greater than 72º C.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-66.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 68/139 procedures, this LED blinks softly approximately every second. After the tests are concluded, if the completion was automatic due to temperature, the LED blinks in 2 intervals in one second, and it is totally off during the next second in this sequence. The E-VGS! Alarm is only deactivated and the LED only goes back to constant “on” state and normal intervals when the drawer is powered off by shutting down the main power. More details of these indications are described in the item that deals with calculations of adjusted coefficients. 20) 42V-H!: Indicates that the power supply has the configuration jumper in manual state (MAN). This alarm always appears when a shut down command occurs and the power supply doesn‟t turn off. In this case, the jumper position must be checked to see if it is on automatic mode (AUTO), as it should always be. Otherwise, the alarms that caused the shutdown of the power supply lose their capability to act and the power supply is left unprotected. 21) NoCh.!: Indicates that the power drawer channel was not programmed. If the channel is not programmed or if it is outside a valid channel band (channel 00 [zero zero] or outside channel band 2 to 69) the power supply of the power drawer is not powered on. The channel information is used by the power drawer to automatically configure the power gain for each channel of the valid band. The channel information is always initialized with the value 00 (zero zero) each time that the power drawer is turned on. After the power drawer is activated, it waits for channel information from two possible command paths, automatic command of the channel programming of the control drawer (main control system of the transmitter) or manual command in the adjustment currents screen of the HyperTerminal (option (4) Drawer Adj. of the main screen and then option (Q) Channel of the adjustment currents screen). When powering down the drawer by turning off main power, the channel information configured by these two commands is lost and set to (zero zero) upon restart in accordance with the standard. 22) Iunb!: Indicates unbalanced current, with a difference of 2.5 amperes less than the rest of the currents; the unbalance is measured only between currents of the output amplifiers. This message appears with other current alarm messages, mentioned before. 23) Izero!: Indicates current close to zero. This message appears with other current alarm messages, mentioned before. 24) Imin!: Indicates current below the minimum value for maintaining good operation of the drawer. For output amplifiers and exciter currents the minimum value is close to 0.8 amperes. Anything below this value generates an alarm. This message appears with other current alarm messages, mentioned before. ATTENTION Any test, maintenance and operation procedures in Linear equipment must be performed by authorized personnel that are trained in transmission equipment for TV signals or by personnel trained in Linear equipment. In case of doubt, contact Linear.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-68.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 81/139 Press ENTER. NOTE: All configuration screens have a four digit menu identification number placed on the right side of the screen. 2.3. Operation Indicators The equipment has LED indicators on the front panel that when illuminated indicate: POWER ON – Equipment is powered. SYNC. LOSS – Loss of input signal. CURRENT ALARM – An alarm went off. PAST ALARM – Existence of an old alarm at the “Alarm Log”. 3. Initialization When powering the equipment, the initialization screen will appear. The initialization screen displays the manufacturer name, module and description, channel, output power in watts, date and time. Pressing any key will move to the next screen, which is the initial menu. Linear Industries Inc. AT75K0 – 8VSB ATSC Digital Exciter Channel: Output Power: 0 [W] DD/MM/YY HH:MM:SS Main Menu: [0000] -> Setup Menu Measurements System Alarms/Log Remote Access](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-81.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 82/139 Information referring to the equipment can be accessed through the main menu, this information includes: input power supply voltage, transport stream, measurements of the drawers, etc. Note: To return the initial screen from the “Main Menu”, just press and hold the ESC key. If after 5 minutes of inactivity the initial screen will automatically return to the original, no matter which screen the display is at. 4. Measurement Systems ITEM OF MEASUREMENT MENU MEASUREMENT DESCRIPTION POWER Forward Direct Power Measurement Reflected Reflected Power Measurement ALC Reference Voltage ALC Voltage Measurement TRANSPORT STREAM Transport Stream Type of input digital signal (ASI / SMPTE310M / NONE) Data Packets Rate Data Packets Rate Measurement: 0 ~ 19,39Mbps Null Packets Rate Null Packets Rate Measurement: 0 ~ 19,39Mbps FIFO Occupation (%) Occupation rate of the FIFO memory used in the rate adaptation (0~100%) DRAWERS POWER SUPPLY 42V Power Supply: drawer input power supply measurement (+42V) CURRENT Current Measurement of the drawer modules TEMPERATURE Temperature Measurement of the drawers EXCITER POWER SUPPLY VOLTAGE +15V Status of the +15V power supply +8V Status of the +8V power supply +3V Status of the +3V power supply +27V Status of the +27V power supply +5V Status of the +27V power supply Main Menu: [0000] -> Setup Menu Measurements System Alarms/Log Remote Access](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-82.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 83/139 Main Menu: [0000] Setup Menu -> Measurements System Alarms/Log Remote Access COMMUNICATION STATUS COMMUNICATION Shows the communication status of the drawers EQP. POWER SUPPLY 15V Status of the 15V power supply 8V Status of the 8V power supply Battery Status of the12V battery SOFTWARE VERSION Digital Exciter Software of the digital exciter Drawer Software of the power drawer Following, the sequence to obtain the measurements above will be shown. 4.1. Transmitter Power Measurements Shows the direct and reflected power measurements in the equipment output, ALC Reference Voltage. To access the Transmitter Power Measurements screen, the sequence of screens below must be followed, starting from the initial menu: Access Measurements Access Power and press ENTER Measurements: [2000] -> Power Transport Stream Drawers Exciter Power Supply Communication Status Eqp. Power Supply Software Version](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-83.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 84/139 Use the screen “ ” to access the other screens in this Menu. To return to the previous screen, press ESC.. 4.2. Measurements relative to the input flux (Transport Stream) Shows information regarding the digital signal. To access the flux measurement screen, the sequence of screens below must be followed, starting from the initial menu: Access Measurements Transmitter Power Measurements: [2100] Programmed: 0 [W] Forward: 0 [W] Reflected: 0.0 [W] ALC Reference Voltage: 0.00 [V] Main Menu: [0000] Setup Menu -> Measurements System Alarms/Log Remote Access Measurements: [2000] Power -> Transport Stream Drawers Exciter Power Supply Communication Status Eqp. Power Supply Software Version](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-84.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 85/139 Select Transport Stream and press ENTER To return to the previous screen, press the key ESC . Drawers Measurements Through this menu, you may access the power measurements, current and temperature of each amplifier module of the power drawer. To check these measurements, press ESC until it returns to the Measurements screen or access Measurements at the Main Menu Select Drawers and press ENTER. Measurements: [2000] Power Transport Stream -> Drawers Exciter Power Supply Communication Status Eqp. Power Supply Software Version Drawer Measurements: [2300] -> Power Supply Current Temperature Transport Stream Measurements: [2200] -> Transport Stream: Sync. Loss Data Packets Rate: 0.00 Null Packets Rate: 0.00 -> FIFO Occupation(%): 0.00%](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-85.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 86/139 Select Power Supply and press ENTER To select a drawer press the keys or Observe the data shown. Press ESC to return to the menu Drawer Measurements. Select Current and press ENTER. Observe the measurements shown. The screens above are the scrolling type, so all the current measurements can be accessed by using the keys and . Press ESC to return to the menu Drawer Measurements. Drawer Power Supply: [2310] Drawer: ◄01/14► 42V Power Supply: 0.0 [V] Drawer Measurements: [2300] Power Supply -> Current Temperature Drawer Current Measurements: [2320] Drawer: ◄01/14► ▼More Modules▲ ->Mod.1 I1: 0.00 A Mod.2 I2: 0.00 A Mod.3 I3: 0.00 A Mod.4 I4: 0.00 A Drawer Current Measurements: [2320] Drawer: ◄01/14► ▼More Modules▲ Mod.3 I3: 0.00 A Mod.4 I4: 0.00 A Excit.I5: 0.00 A Excit.I6: 0.00 A Drawer Measurements: [2300] Power Supply Current -> Temperature](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-86.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 87/139 Select Temperature and press ENTER. To select different drawers, press the keys ◄ or ►. To change the temperature reading unit, °C for °F, press the keys ▼ or ▲. 4.4 Medidas das Tensões do Excitador Digital These screens show the voltage status at the digital exciter power supply. Press ESC until it returns to the Measurements screen [2000] Select Exciter Power Supply and press ENTER To access all of the voltage measurements of the screen above, just use the keys or . Press ESC until it returns to the Measurements screen [2000] Drawer Temperature Measurements: [2330] Drawer: ◄01/14► Exciter: 0.0 ºC ▼ºF▲ Mod.1: 0.0 ºC Mod.2: 0.0ºC Mod.3: 0.0 ºC Mod.4 0.0ºC Measurements: [2000] Power Transport Stream Drawers -> Exciter Power Supply Communication Status Eqp. Power Supply Software Version Exciter Power Supply: [2400] -> +15V : OK +8V : OK +3V : Fail +27V : OK +5V : OK](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-87.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 88/139 4.5 Drawers Communication Status From this screen it is possible to verify the communication status of each power drawer. To check the communication status, press ESC until it returns to the Measurements screen or access Measurements from the Main Menu. Select Communication Status and press ENTER. To return to the previous screen press ESC. 4.6 Voltages of the Power Supply Shows the condition of the voltages in the power supply (located at the back of the rack) of the equipment. To check these voltages, access Measurements at the Main Menu. 4.6 Tensões da Fonte de Alimentação Measurements: [2000] Power Transport Stream Drawers Exciter Power Supply -> Communication Status Eqp. Power Supply Software Version Drawers Communication Status: [2500] ->P01: -- P02: -- P03: -- P04:-- P05: -- P06: -- P07: -- P08:-- P09: -- P10: -- P11: -- P12:-- P13: -- P14: --](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-88.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 89/139 Select Eqp. Power Supply and press ENTER Press ESC until it returns to the main menu. 4.7 Software Version This screen indicates the name of the software and its version. Three families of software are shown; the FPGA software present on the ATSC modulator, the Micro-controller software on the digital exciter unit, and the micro-controllers unit installed on the RF Power Drawers. All these names and version should be available to be report to the factory when necessary. Press ESC until it returns to the Measurements screen [2000] The sequence below indicates how to access the software version screen: Measurements: [2000] Power Transport Stream Drawers Exciter Power Supply Communication Status -> Eqp. Power Supply Software Version Power Supply Measurements: [2600] 15V: OK 8V: OK Battery: 12.5[V] Measurements: [2000] Power Transport Stream Drawers Exciter Power Supply Communication Status Eqp. Power Supply -> Software Version](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-89.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 90/139 Select Software Version and press ENTER To select different drawers, press the keys ◄ or ►. Press ESC to return to the Main Menu. 5. Alarm System The equipment has indicator LEDs mounted on the frontal panel, one LED indicates loss of the input signal (SYNC. LOSS), another LED represents a new alarm situation (CURRENT ALARM) and another LED indicates the presence of an old alarm on the log (PAST ALARM), in other words, an error condition caused an alarm but the condition has been resolved but not cleared from the log. Under normal conditions of operation, only the POWER ON / OFF LED is on. Once the CURRENT ALARM LED is on, you must access the System Alarms to identify the problem. Log in the main menu and check the System Alarms Log to learn which specific alarm has been triggered. Below is shown how to access the alarm screen from the main menu. Access System Alarms/Log Software Versions: [2700] Digital Exciter: AT1035 0.2 Drawer ◄01/14► : GP3000 1.8 FPGA: AL1019 V.1.1 Main Menu: [0000] Setup Menu Measurements -> System Alarms/Log Remote Access](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-90.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 91/139 Select Current Alarms and press ENTER If there is no alarm the message “Alarm List Empty!” will appear. Press the ESC key to return to the menu System Alarms/ Log menu. System Alarms/Log: [3000] -> Current Alarms Alarm Log Drawers Alarms Clear Alarm Log Current Alarms: [3100] Alarms List Empty! System Alarms/Log: [3000] Current Alarms -> Alarm Log Drawers Alarms Clear Alarm Log](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-91.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 92/139 To check all the existing alarms, in other words, alarms that are occurring now and alarms that no longer are occurring, select Alarm Log and press ENTER. The symbol “I” before the log indicates that the time the alarm occurred is registered. The symbol “#” before the log indicates that the time the alarm stopped occurring is registered. Example: When an alarm stops occurring, besides having the exact time registered on the log, the LED indicator of “PAST ALARMS” will turn on. In the case there are more than 3 alarms in the log, just key “ ” to scroll the log. The storage capacity is 100 entries. If the option Clear Alarm Log is selected, all alarms will be erased from the alarm log and a new first item will be generated indicating the time the alarm log was erased. Every alarm generated has its date and time registered in the log. The „Current Alarm‟ indicator LED illuminates to indicate a current alarm and the Sync Loss‟ indicator LED illuminates to indicate a loss of signal. Drawers Alarms Allows the review of current and past alarms on each power drawer. To access this screen, select the System Alarms/Log from the main menu. Alarm Log: [3200] -> ! 25/03/08 10:55:29 Log Cleared ! 28/03/08 20:19:05 LO Lock Fail # 28/03/08 20:22:43 LO Lock Fail Main Menu: [0000] Setup Menu Measurements -> System Alarms/Log Remote Access](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-92.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 93/139 Select System Alarms/Log and press ENTER Select Drawers Alarms and press ENTER. Select Current Alarms and press ENTER to check for current alarms. Use the keys or to select the drawer. Press the key ESC to return to the screen Drawers Alarms. Select Past Alarms and press ENTER to check for past alarms. To select different drawers, press the keys ◄ or ►. Drawers Alarms: [3300] -> Current Alarms Past Alarms (Hold Enter to Clear) Drawer ◄01/14► Current Alarms: [3310] Alarm List Empty! Drawers Alarms: [3300] Current Alarms -> Past Alarms (Hold Enter to Clear) Drawer ◄01/14► Past Alarms: [3320] Alarm List Empty! System Alarms/Log: [3000] Current Alarms Alarm Log -> Drawers Alarms Clear Alarm Log](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-93.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 95/139 6.1 Programming the transmission power level Commands the software to set the transmission power of the equipment. To access the programming screen of the transmission power, the following sequences of screens must be followed, starting from the main menu. Select Setup Menu and press ENTER Select Power Setup and press ENTER Main Menu: [0000] -> Setup Menu Measurements System Alarms/Log Remote Access Setup Menu: [1000] -> Power Setup Transmitter Setup Image Frequency Suppression LO Leakage Suppression Pre-Correction Modulation Settings Time and Date Setup Password Setup](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-95.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 96/139 To select the desired power, the key must be used to increase the power or the key to decrease it. In case you desire to increase or decrease the power rapidly, just press and hold the or key until you reach the desired value. After the power is selected, press ENTER. IMPORTANT: THIS PROGRAMING DOES NOT CHANGE THE TRANSMISSOR OUTPUT POWER. THE EQUIPMENT IS CONFIGURED BY THE MANUFACTURER AND MUST NOT BE CHANGED. 6.2 Transmitter Setup Under this menu it is possible to turn ON and turn OFF the ALC (Automatic Level Control), mute the or not the RF power output on the event of absence of Transport Stream, and also select being local or remote the transmitter power level control. Power Setup: [1100] Output: 0 [W] Program: 0 [W] Remote Control Active. Setup Menu: [1000] Power Setup -> Transmitter Setup Image Frequency Suppression LO Leakage Suppression Pre-Correction Modulation Settings Time and Date Setup Password Setup](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-96.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 97/139 Select Transmitter Setup and press ENTER. To configure the options as shown on the screen [1200] above, use the keys ◄ or ►. Press ESC to return to Setup Menu. Select Image Frequency Suppression and press ENTER. The screen below will appear. Transmitter Setup: [1200] -> Automatic Level Control: On Mute on TS Loss: On Power Control: Local Setup Menu: [1000] Power Setup Transmitter Setup -> Image Frequency Suppression LO Leakage Suppression Pre-Correction Modulation Settings Time and Date Setup Password Setup WARNING!! Changing these parameters may damage the equipment. Use appropriate instruments to do it. Continue? ◄ No ►](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-97.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 99/139 6.3 Image Frequency Suppression Allows the configuration of numeric values related to the amplitude and phase of the signal for the suppression of the image frequency (superior lateral band). Both amplitude adjustments are set in [dB] and both phase adjustments are set in [degrees]. Press ESC until it returns to the Setup Menu. Select LO Leakage Suppression and press ENTER. Image Frequency Suppression: [1300] -> I Amplitude: -0.000 [dB] Q Amplitude: -0.000 [dB] I Phase : + 0.00º Q Phase : + 0.00º Setup Menu: [1000] Power Setup Transmitter Setup ` Image Frequency Suppression -> LO Leakage Suppression Pre-Correction Modulation Settings Time and Date Setup Password Setup](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-99.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 100/139 The screen below will appear. ATTENTION: When accessing this screen, by selecting option “YES”, the operator will be responsible for the changes done on this parameter, as well as the effects that these changes may cause in the equipment if not using the appropriate instruments and test point. To access the LO Leakage Suppression screen, select “Yes” by using the keys or . . 6.4 LO Adjustment (LO Leakage Suppression) Sets the DC voltage configuration of the signal leakage suppression adjustment system for the local oscillator of the Up Converter with the following range of values: -60 [mV] to +60 [mV]. Use the keys or to adjust the value. WARNING!! Changing these parameters may damage the equipment. Use appropriate instruments to do it. Continue? ◄ No ► LO Leakage Suppression: [1400] -> I Offset: + 0.00 [mV] Q Offset: + 0.00 [mV]](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-100.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 101/139 6.5 Activate/De-activate Pre-Correction Through these screens it is possible to activate or de-activate the linear and non-linear pre-correction. ON: activate the pre-correction OFF: de-activate the pre-correction To access this screen, press ESC until reaching the SETUP MENU screen. Setup Menu: [1000] Power Setup Transmitter Setup Image Frequency Suppression LO Leakage Suppression -> Pre-Correction Modulation Settings Time and Date Setup Password Setup](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-101.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 102/139 Access Pre-Correction and press ENTER The screen below will appear: ATTENTION: When accessing this screen, by selecting option “YES”, the operator will be responsible for the changes done on this parameter, as well as the effects that these changes may cause in the equipment if not using the appropriate instruments and test point. To access the Pre-Correction screen, select “Yes” by using the keys or . Select Linear and press ENTER WARNING!! Changing these parameters may damage the equipment. Use appropriate instruments to do it. Continue? ◄ No ► Pre-Correction Setup: [1500] -> Linear Non-Linear](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-102.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 103/139 Use the keys ◄ or ► to enable or disable the Linear pre-correction. Press key ESC to return to the Pre-Correction Setup screen. Select Non-Linear and press ENTER Use the keys ◄ or ► to enable or disable the non-Linear pre-correction The option Scale is the configuration of the pre-distortion scale (or intensity) applied to the ATSC signal, with the following range of values: -300 to +300. Press key ESC to return to Setup Menu. 6.6 Modulation Settings Through this screen it is possible to turn on/off the modulation and configure the desired level for the pilot portal of the ATSC signal with the following range of values: -2048 to +511. Non-Linear Pre-Correction: [1520] -> Non-Linear Pre-Correction: Off Scale: +000 Pre-Correction Setup: [1500] Linear -> Non-Linear Linear Pre-Correction: [1510] Linear Pre-Correction: On](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-103.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 104/139 Select Modulation Settings and press ENTER. The screen below will appear: ATTENTION: When accessing this screen, by selecting option “YES”, the operator will be responsible for the changes done on this parameter, as well as the effects that these changes may cause in the equipment if not using the appropriate instruments and test point. To access the Modulation Settings screen, select “Yes” by using the keys or and press the key ENTER. Use the keys ◄ or ► to enable or disable the modulation, and/or also adjust the pilot level. Setup Menu: [1000] Power Setup Transmitter Setup Image Frequency Suppression LO Leakage Suppression Pre-Correction -> Modulation Settings Time and Date Setup Password Setup WARNING!! Changing these parameters may damage the equipment. Use appropriate instruments to do it. Continue? ◄ No ► Modulation Settings: [1600] -> Modulation: On Pilot Level Offset: +0000 (-2048 to 511)](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-104.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 105/139 6. Configuring Date and Time To access the programming screen for date and time, the operator must press ESC until it returns to the SETUP Menu. Select Time and Date Setup and press ENTER 6.8 Programming the Password Allows for entering a four digit number to be used as the password to access the equipment settings. The decrease the digits. Once in this screen, it is only possible to exit after the password is set. To access the password configuration screen, the operator must follow the sequences below, starting from the SETUP MENU. Setup Menu: [1000] Power Setup Transmitter Setup Image Frequency Suppression LO Leakage Suppression Pre-Correction Modulation Settings -> Time and Date Setup Password Setup Time and Date Setup: [1700] Time: 00:00 Date: 00/00/00 DD/MM/YY](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-105.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 106/139 Access Password Setup To enable a password or to enter a new one, select Enable / Choose new password. The option Disable password if selected dispenses the use of password. 7. Remote Management System (Tele-supervision) All of the equipment parameters such as: transmission power level, power supply measurements, alarm verification and all the possible functional selections may be accessed two different ways. Frontal Panel – Through the frontal panel all of the equipment measurements and configurations may be accessed, as shown in the operation section. Setup Menu: [1000] Power Setup Transmitter Setup Image Frequency Suppression LO Leakage Suppression Pre-Correction Modulation Settings Time and Date Setup -> Password Setup Password Setup: [1800] -> Enable / Choose new password Disable password New Password: [1810] 0 0 0 0 Write New Password](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-106.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 107/139 Local or remote PC via Ethernet or GPRS (optional). It is possible to change and/or monitor all of the parameters and measurements as is done at the frontal panel through the WEB server. To accomplish this it is necessary to configure the IP / Mask / Gateway. 7.1 IP Configuration From the main menu: Select Remote Access and press ENTER Select IP Address and press ENTER. Configure the desired IP by using the keys or and or Main Menu: [0000] Setup Menu Measurements System Alarms/Log -> Remote Access Remote Access: [4000] -> IP Address Subnetwork Mask Gateway IP Address: [4100] 192.168.100.018](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-107.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 108/139 7.2 Mask Configuration To access this screen, press ESC until the Remote Access screen reached. Select Subnetwork Mask and press ENTER or and 7.3 Gateway Configuration To access this screen, press ESC until the Remote Access screen reached. Access Gateway and press ENTER Configure the gateway by using the keys or and or Remote Access: [4000] IP Address -> Subnetwork Mask Gateway Subnetwork Mask: [4200] 255.255.255.000 Remote Access: [4000] IP Address Subnetwork Mask -> Gateway Gateway: [4300] 192.168.100.001](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-108.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 115/139 4. Run – Single iteration algorithm to compensate for non-linear distortions. 5. Memory Effects Compensation – Check this box to compensate for memory non-linear distortions. Uncheck to compesante for memoryless distortions only. 6. Save – Push this button to save the result on the non-volatile memory. 7. Back – Close current window. 8. AM/AM – Figure that shows the AM/AM behavior for the pre-correction. 9. AM/PM – Figure that shows the AM/PM behavior for the pre-correction. 10. DUT – If the Memory Non-Linear Pre-Correction option is enabled, two PA memory models may be selected: Type A and Type B; try both to compare which one fits better. Memory-less vs. Memory Pre-Correction – Non-linearity is present when the AM/AM and AM/PM transfer functions are not straight lines, i.e., when the DUT (Device Under Test) has not a constant gain and a constant output phase delay with respect to the input amplitude. When such distortions don't change with time they're called memoryless non-linearity, or static non-linearity. It means the output signal at the present moment depends only on the input signal at the present moment also. However, some amplifiers present a dynamic behavior. Their AM/AM and AM/PM behavior change with time in a short time range (nano / micro seconds). It happens because the output signal at the present moment doesn't depend on the input signal at the present moment only, but also on its previous values. It generates more distortion, and a memoryless pre-corrector is not able to compensate for these memory effects. This pre-correction is an automatic procedure. It uses a signal taken from a feedback sample located between the power amplifier output and the mask filter input. Perform the following steps to run the pre-correction: 1. Connect the AT7001 RF output to the amplifier to be linearized. If an output filter is used, run the algorithm with the filter connected to the amplifier because the reflected signal coming from the filter may change the amplifier behavior. 2. Set the desired power. 3. Take the Before Filter Feedback Sample and make sure is connected the AT7001 rear panel before running the pre-correction. The coupler used for the sample must be directional, with isolation greater than 15 [dB] in order avoid miscalculation created by a reflected signal. The coupling port must have a 50 [Ω] impedance in order to avoid a linear distortion in the feedback path. Also the coupling port response must be as flat as 0.3 [dB] in a 30 [MHz] range. The feedback sample level must be between -10 and 0 dBm. You can use the Signal Measurements software to check if the feedback sample is present.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-115.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 118/139 Figure 7a – Memoryless curves. Figure 7b – Memory curves. The memory curves (Figure 7b) are three dimensional plots, where the color means amplitude (in [dB]) for AM/AM and phase (in [°]) for AM/PM. A distortion is present when horizontal parallel lines present different colors. When Crest Factor Reduction is used, intermodulation may be reduced. However there is a trade-off with three collateral effects: ➢ MER reduction ➢ Frequency response distortion ➢ Image frequency rejection Figure 8 represents typical results when Crest Factor Reduction is used.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-118.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 121/139 2. Set the nominal power. 3. If an amplifier is used, run the non-linear pre-correction first, and then the linear pre-correction. This will make linear calculation more accurate. 4. Make sure the After Filter Feedback Sample is connected the AT7001 rear panel before running the pre-correction. The coupler used for the sample must be directional, with an isolation greater than 15 [dB] in order avoid miscalculation created by a reflected signal. The coupling port must have a 50 [Ω] impedance in order to avoid a linear distortion in the feedback path. Also the coupling port response must be as flat as 0.5 [dB] in a 30 [MHz] range. The feedback sample level must be between -10 and 0 dBm. You can use the Signal Measurements software to check if the feedback sample is present. 5. Click on Run. The whole process consists of single iteration. After a few seconds, the results will be applied automatically. Crest Factor Reduction will be automatically bypassed when the algorithm is running. 6. Once the correction achieves satisfying results, click on Save push-button to save the curves on the non-volatile memory. Figure 10 presents the corresponding curves used to compensate a mask filter. Figure 10 – Typical Linear Pre-Correction Curves.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-121.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 123/139 5. Measurement Window – This Figure shows the last active measurement. 6. File => Export – Use this option to export the measurement to one of the following formats: – .emf => Enhanced Metafile. – .eps => Encapsulated Postscript. – .jpeg => Joining Photograph Experts Group. – .pdf => Portable Document Format. 7. Information Bar – This bar shows additional information regarding the last measurement. It is useful to evaluate the signal compression caused by the amplifier non-linearity, as it gets close to the saturation region. Perform this measurement using Feedback Before Filter sample. Figure 12 shows a signal that has been compressed at the saturation level and expanded at the turn-on region, typical in class AB amplifiers. The information bar will show two additional pieces of information: Error: Shows the Mean Squared Error between the Input and Feedback signals. Peak Compression: shows in [dB] how much the maximum peak found was compressed. Figure 12 – Amplitude Modulus Measurement.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-123.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 124/139 AM/AM – AM/AM stands for Amplitude Modulation / Amplitude Modulation, it represents the normalized output/input amplitude ratio (amplifier gain) in [dB] vs. normalized input amplitude in [dB] Full Scale. The blue points show the Instantaneous Transfer Function, as it has a dynamic behavior. Their spread characteristic is caused by noise and memory effects. The red line is the Memoryless Transfer Function that best fits the blue points. This is a powerful tool to evaluate a power amplifier transfer function, and thus its linearity. Check how spread the blue points are in order to realize how much memory effects the amplifier has. Always perform this measurement using Feedback Before Filter sample. The information bar will show the additional information: ✔ Peak to peak amplitude distortion: Shows the Memoryless Transfer Function peak to peak value. Figure 13 – AM/AM Measurement.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-124.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 125/139 AM/PM – AM/PM stands for Amplitude Modulation / Phase Modulation, it represents the phase deviation in [°] vs. normalized input amplitude in [dB] Full Scale. The blue points show the Instantaneous Transfer Function, as it has a dynamic behavior. Their spread characteristic is caused by noise and memory effects. The red line is the Memoryless Transfer Function that best fits the blue points. This is a powerful tool to evaluate a power amplifier transfer function, and thus its linearity. Check how spread the blue points are in order to realize how much memory effects the amplifier has. Always perform this measurement using Feedback Before Filter sample. The information bar will show the additional information: Peak to peak amplitude distortion: Shows the Memoryless Transfer Function peak to peak value. Figure 14 – AM/PM Measurement.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-125.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 126/139 CCDF – CCDF stands for Complementary Cumulative Distribution Function. It represents the probability (vertical axis) of the Instantaneous Power be “x” [dB] above the average power, where “x” is the value in the horizontal axis. For example, suppose an amplifier is driving 1 [kW] into a dummy load, and the Feedback Sample was taken from its output. In the measurement below (Figure 15), the 0 [dB] point has a probability around 40 [%]. It means 40 [%] of time the Instantaneous power is above 1 [kW] (or 0 [dB]) and thus 60 [%] of time the Instantaneous power is below the average power (1 [kW]). Now another example: the 6 [dB] point for the Feedback signal (red dashed line), has a probability of 0.07 [%]. It means that 99.93 [%] of time, the Instantaneous Power is below 4 [kW] (6 [dB]), but for very few time, or 0.07 [%] of time, the amplifier will drive a power above 4[kW]. It is clear that the amplifier compressed the high amplitudes, because the red line is below the blue one. Use this measurement to evaluate how much an amplifier has compressed or clipped a signal. The information bar will show the additional information: – PAPR: Stands for Peak to Average Power Ratio and represents the ratio between the maximum peak power found and the average power. Shown for both Input and Feedback signals. Figure 15 – CCDF Measurement.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-126.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 127/139 Constellation – the constellation is a diagram of the sampled baseband modulating symbols, where the Cartesian plan is plotted by its real vs. imaginary part. The real part (In Phase) of those sampled symbols carry the transmitted information while the imaginary part (Quadrature) carry the necessary information to generate the vestigial side band. For 8VSB modulation, the eight regions represent the eight possible symbols, and the seven dashed lines indicate the decision threshold. This measurement reflects the signal quality. Use it to realize non-linear, linear and amplitude distortions. The information bar will show the additional information: MER: Modulation Error Rate. It is the mean squared error in [dB] considering the perfect symbol as the reference signal. Figure 16 – Constellation Measurement.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-127.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 128/139 Constellation Contour – the constellation is a diagram of the sampled baseband modulating symbols, where the Cartesian plan is plotted by its real vs. imaginary part. The real part (In Phase) of those sampled symbols carry the transmitted information while the imaginary part (Quadrature) carry the necessary information to generate the vestigial side band. For 8VSB modulation, the eight regions represent the eight possible symbols, and the seven dashed lines indicate the decision threshold. The Constellation Contour differs from the Constellation in the sense it shows probability regions for a demodulated symbol to fall in coded in colors. A red area means high probability, as the blue area means low probability. This measurement reflects the signal quality. Use it to realize non-linear, linear and amplitude distortions. The information bar will show the additional information: MER: Modulation Error Rate. It is the mean squared error in [dB] considering the perfect symbol as the reference signal. Figure 17 – Constellation Contour.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-128.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 129/139 Eye Diagram – The Eye Diagram is the purely real modulating symbols filtered with a raised cosine filter and persisted with a symbol period multiple. The open eyes points indicate the exact moment for the receiver to sample and decide in order to extract the message. Eyes wide open are desired. This measurement reflects the signal quality. Use it to realize non-linear, linear and amplitude distortions. The information bar will show the additional information: MER: Modulation Error Rate. It is the mean squared error in [dB] considering the perfect symbol as the reference signal. Figure 18 – Eye Diagram Measurement.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-129.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 132/139 Power Spectrum Density – This is a spectral analysis using the Power Spectrum Density estimation of the IF signals. The in-band signal average power is normalized to be the 0 [dB] point. The information bar will show the additional information: Shoulders attenuation @ -+ 3.25 [MHz]: shows the shoulder attenuation @ -+ 3.25 [MHz] from channel center frequency relative to the in-band average power with a 500 [kHz] equivalent resolution bandwidth. Figure 21 – Power Spectrum Density Measurement.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-132.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 133/139 Symbols – This measurement represents the purely real demodulated symbols over time. Figure 22 shows the demodulated symbols after a mask filter without linear pre-corrections and then with. Straight indicates a high MER signal. The information bar will show the additional information: MER: Modulation Error Rate. It is the mean squared error in [dB] considering the perfect symbol as the reference signal. Figure 22 – Symbols Measurement.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-133.png)
![AT75K0-1 Owner’s Manual © 2009 Linear Industries, Inc., all rights reserved OM_10/09 135/139 Time Domain – This measurement shows both input and feedback IF signals at the same time in time domain. The information bar will show two additional pieces of information: Error: Shows the Mean Squared Error between the Input and Feedback signals. Figure 25 – Time Domain Measurement. 3.4 Calibration Every AT7001 unit presents a internal linear distortion on feedback path. This distortion is compensated during linear pre-correction. However is not present at the mask filter. It generates an error that may be avoided using the calibration process. 1. Set the output power do 0 [dBm]. 2. Make an external loop; connect the RFoutput on After Filter Feedback Sample in. 3. Bypass the Non-Linear and Linear Pre-Corrections. 4. Open the Signal Measurements window and Measure Frequency Response between Input and Feedback After Filter. The result is going to be the internal linear distortion to be calibrated.](https://usermanual.wiki/Hitachi-Kokusai-Electric-America/AT75000/User-Guide-1191073-Page-135.png)
