Robotron G5E USB VHF/UHF Receiver User Manual Appendix G
Robotron Pty Ltd USB VHF/UHF Receiver Appendix G
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![WiNRADiO G3XX User’s Manual Scanning The WiNRADiO G3XX application contains a comprehensive set of scan functions to enable the user to search for stations which are currently on the air. There are three basic types of scanning: Immediate Scanning (Searching), Range Scanning and Memory Scanning. The scanning method is selected using the appropriate button in the Scanning Control Panel: Immediate Scanning (Searching) This is the simplest scanning method. Click on the Search button to select this scanning mode, then use the [>>] or [<<] buttons to scan either forward or backward from the currently tuned frequency. To stop scanning, press the Stop button (marked with a green square). To pause, press the Pause button (marked with two vertical bars). If you are using the Signal level type of squelch, then a signal is considered ‘found’ when the signal level becomes higher than the squelch level. If you set the squelch level too low, scanning will stop even if there is no signal (the background noise peaks will exceed the squelch level). On the other hand, if the squelch level is set too high, then a useful signal may be missed because it will fall short of the squelch level. Correct setting of the squelch value is therefore essential for scanning. With a bit of trial and error, you will need to adjust the optimum setting for the squelch level (usually a few dB above the background noise floor). With Noise squelch (which is especially recommended for use in FM mode), the signal will be ‘found’ if the receiver finds a channel where the audio is less noisy, i.e. when the audio has been quietened by receiving an FM modulated signal and the noise level has fallen under the preset limit. The optimum setting varies, depending on the IF bandwidth (the wider the bandwidth, the higher will be the setting, because the noise on an unoccupied channel will be also stronger). 51](https://usermanual.wiki/Robotron/G5E/User-Guide-642078-Page-52.png)
![WiNRADiO G3XX User’s Manual 53 The scanning speed is determined by the scanning step size. The scanner tunes the receiver in increments of 10 kHz and uses 10 kHz wide “chunks” of the IF spectrum to search for a signal. If the step size is 10 kHz, the typical scanning speed will be approximately 40 channels per second. If the step size is 5 kHz, then the scanner only needs to retune the receiver once per every two steps, which results in a nearly double the effective scanning speed. For 1 kHz steps, the effective scanning speed will be approximately 400 channels per second. Note that the maximum scanning speed may be limited by the actually available CPU resources of your computer. When a signal is found and scanning pauses, waiting for the pre-set Delay time to expire, the countdown timer will appear inside the [<<] or [>>] buttons. If no Delay time was set and scanning is pausing until the signal disappears, then the [<<] or [>>] button will flash. Groups The Groups setting is useful for Memory Scanning, which will be described in detail later: it serves to restrict Memory Scanning to particular memory groups only. Exclusions Sometimes it is desirable to exclude certain frequencies from scanning. This means that such specified frequencies should be ignored, even if the signal level on these frequencies is higher than the squelch. The WiNRADiO G3XX receiver application makes it possible for multiple frequency ranges to be excluded. This is done using the Exclusions button. When you press this button, you will open an Exclusions editor window, allowing you to enter a range of frequencies to be excluded. For these exclusions to become active, check the Enable excluding while scanning checkbox in this window.](https://usermanual.wiki/Robotron/G5E/User-Guide-642078-Page-54.png)
![WiNRADiO G3XX User’s Manual To create a new range, click the New button. This will open a dialog box, where you can specify lower and upper limit frequencies of the range, the step size, modulation mode, squelch level, and, optionally, a description. You can enter as many such ranges as you like. When the range definition is done, close this window, then close the scanner settings. Then activate the Range button in the Scanning control panel: When you press the Scan Forward button [>>], the scanner will commence scanning from the start frequency of the first range. When the last frequency of the first range is reached, it will then continue onto the next range, etc. When it reaches the end of the last range, it will go back to the start of the first range and continue looping infinitely until a signal is found, or until manually stopped or paused. If you use the Scan Backward [<<] button, the process will be exactly reversed (i.e. starting from the top frequency of the last range and working its way downwards). 55](https://usermanual.wiki/Robotron/G5E/User-Guide-642078-Page-56.png)
![WiNRADiO G3XX VHF/UHF Receiver 70 Another way to solve this problem is to close the G3XX application and manually edit the wrG3XXni file in the Windows directory. For example, you will see values similar to these: [Scope-03E27014] Visible=1 Height=300 where 03E27014 is the serial number of your receiver. Your 'Height' value is probably greater, but you should change it to a reasonable value (about 200).](https://usermanual.wiki/Robotron/G5E/User-Guide-642078-Page-71.png)
![WiNRADiO G3XX VHF/UHF Receiver 82 Appendix H – Frequency Calibration The G3XX receiver series features an excellent frequency accuracy and stability for a receiver of its class. It is however possible to improve this accuracy yet further, by individual calibration. The receiver calibration is accomplished by inserting a reference frequency parameter in the wrG3XX.ini file which resides in the Windows directory. The reference frequency parameter consists of two lines of the following format: [ClockCalibration] receiver_serial_number=reference_frequency The receiver serial number can be obtained for example from the About box in the G3XX application. The reference frequency is the actual frequency of the internal reference oscillator in Hz. This is normally 16.384 MHz, i.e. 16384000 Hz. Each receiver is factory calibrated, so a fundamental correction to the nominal 16.384 MHz reference frequency already exists and is stored in the receiver's internal memory. This correction can be overridden by the new parameter in the wrG3XX.ini file. To determine the true offset from a perfect tuning, firstly use 16384000 (i.e. the nominal reference frequency in Hz) as the reference_frequency parameter. Say your receiver serial number is 02L27011: [ClockCalibration] 02L27011=16384000 Save the wrG3XX.ini file with this value, then start the G3XX application. The frequency error will be now much worse because the new parameter overrides the original factory calibration. Then tune the receiver to a known frequency standard. A high-accuracy signal generator can be used, or one of the WWV Time and Frequency Standard stations. Observe the peak with the spectrum scope and listen to the beat frequency in the CW mode with a minimum IF bandwidth. Then note down the frequency difference. (For example, -152 Hz at 10 MHz).](https://usermanual.wiki/Robotron/G5E/User-Guide-642078-Page-83.png)
![WiNRADiO G3XX User’s Manual 83 Then scale the frequency difference to 16.384 MHz. For example, if the frequency difference is -152 Hz at 10 MHz, it will be -249 Hz at the 16.384 MHz reference frequency. To arrive at the corrected reference frequency, subtract the frequency difference from 16384000. In our example, 16384000-(-249)=16384249. The entire reference frequency parameter in the wrG3XX.ini file will be then as follows: [ClockCalibration] 02L27011=16384249 Save the wrG3XX.ini file, then restart the G3XX application and observe the difference. To return to the original factory frequency calibration, simply delete the inserted two lines in the wrG3XX.ini file. You can also delete the entire file (which will however result in losing all current receiver settings and return to factory defaults for all of them). Did you know? The WWV Time and Frequency Standard station which broadcasts on 2.5, 5, 10, 15 and 20 MHz, has a long history that dates back to the very beginning of radio broadcasting. The call letters WWV were assigned to the US National Institute of Standards and Technology (then called the National Bureau of Standards) in October 1919. By December 1922, it was decided that the station’s purpose would be the transmission of standard frequency signals. The accuracy of the transmitted frequency was quoted as being better than 0.3 per cent. Nowadays the station frequency is controlled within one part in 1013, which represents frequency accuracy thirty billion times better.](https://usermanual.wiki/Robotron/G5E/User-Guide-642078-Page-84.png)
