BER jumping all over the place

General support for the Pi-Star System
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KE2SJ
Posts: 85
Joined: Thu May 17, 2018 5:38 pm

BER jumping all over the place

Post by KE2SJ »

My BER is jumping all over the place, no matter what Pi or Hat I use or how I adjust RF offset. While I can lower it a bit, one transmission will be 0.7 and the next will be 5.4. I'm using a MMDVM hotspot with a dual slot hat made by a reputable manufacturer. This only seems to happen with DMR and happens even with the simplest DMR config. All help appreciated!
AF6VN
Posts: 821
Joined: Fri Jul 20, 2018 1:15 am

Re: BER jumping all over the place

Post by AF6VN »

You left off a crucial factor... What /radio/ are you using!

BER for your outgoing transmissions tends to reflect subtle frequency offsets between your radio and the RF module mounted on the R-Pi. Setting offsets in the RF module tweaks the center frequency used for Tx/Rx. A radio with less-than-stellar frequency control could be drifting to either side -- based upon anything (temperature is most likely, followed by maybe capacitive coupling to your hand or flexible wires). Not that this is the only cause for BER...

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AF6VN
Dennis L Bieber
KE2SJ
Posts: 85
Joined: Thu May 17, 2018 5:38 pm

Re: BER jumping all over the place

Post by KE2SJ »

Thanks. I'm using an Anytone 878. I had already used MMDVMCal, which resulted in a minor TXoffset adjustment, nothing that fixed the BER jumping all around.
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