Receiver Frequency Error Compensation

The receiver must be tuned exactly to the frequency setting received from the decoder. Any offset must be corrected and entered into the system via the Freq Offset field in the Configuration | Receiver and Satellite Settings... dialog.

The following procedure can be used to find out and correct this offset:

Ø After start of the SAT Mode, wait until the receiver displays the frequency of the control channel (see the NCSC table below and take into account down converter use).

Ø Select spectrum analysis (VHF/UHF Modes/Analysis DIRECT/Real-time FFT) on the user interface of the decoder. Make sure all the settings are still correct (Input, Offset). Select a bandwidth of 24 kHz, set Averaging to about 4 or 5.

Ø The spectrum of the control channel is about 8 kHz wide, and it should be adjusted so it is in the centre of the 24 kHz FFT display. If this is not the case, determine the frequency offset - if the spectrum is too far to the right of the display, the sign of the offset is negative, otherwise it is positive.

Ø Now, close the FFT window, select Configurationet | Receiver and Satellite Settings....Enter the amount and sign of the frequency offset into the Freq Offset field.

Ø Start the SAT Mode again, after the receiver has been retuned taking the frequency offset into consideration. Select the FFT again and check if the control channel is now exactly in the middle of the FFT display. Repeat the adjustment if necessary. It is very important that the control channel spectrum should not be offset more than 100 Hz, i.e., it should be symmetrically centered.