Pistar RX offset etc.
Posted: Sat Jul 18, 2020 1:18 pm
I've been able to fine-tune the transmission frequency in FM mode of my 2 old GD77's and my new DM-1801
With the frequency meter drived by satellite, I finally got +25 Hz, +35 Hz, +20 Hz after warm-up so I can consider that my 3 HT are correctly and identically tuned.
The DM-1801 is used for the hotspot function.
Obviously the TXoffset is set to 0 in Pistar.
When I transmit with either my GD-77's, If I logically set the RXoffset to 0 too, my BER si bad and fluctuates a lot.
In Pistar I have to set the RXoffset to -900 or -1000 to have the best BER, which is 0 or 0,1%
The RXoffset value is not critical at all, but I found -900/-1000 to be the best choice.
If I replace the GD-1801/hotspot with a GD77, I have to maintain this -900/-1000 RXoffset in Pistar too.
So I tend to assume that there is an offset between the transmit and receive frequencies?
(I wanted to low the RX frequency of all my DMR channels by 1 kHz in the CPS but it is not possible as the CPS rounds up to the nearest 2,5 kHz)
With the frequency meter drived by satellite, I finally got +25 Hz, +35 Hz, +20 Hz after warm-up so I can consider that my 3 HT are correctly and identically tuned.
The DM-1801 is used for the hotspot function.
Obviously the TXoffset is set to 0 in Pistar.
When I transmit with either my GD-77's, If I logically set the RXoffset to 0 too, my BER si bad and fluctuates a lot.
In Pistar I have to set the RXoffset to -900 or -1000 to have the best BER, which is 0 or 0,1%
The RXoffset value is not critical at all, but I found -900/-1000 to be the best choice.
If I replace the GD-1801/hotspot with a GD77, I have to maintain this -900/-1000 RXoffset in Pistar too.
So I tend to assume that there is an offset between the transmit and receive frequencies?
(I wanted to low the RX frequency of all my DMR channels by 1 kHz in the CPS but it is not possible as the CPS rounds up to the nearest 2,5 kHz)