DSDPlus with Airspy single SDR Trunking bandwidth

[msingewald]

Running Fastlane 2.212 with an Airspy in single SDR mode tracking a P25 system. I set the bandwidth to 12.5 in the FMPA-CC batch file, and it starts correctly. However, once I execute the 1Ra batch file and it tunes voice traffic, the bandwidth in FMPA changes to 9.5

Is this normal or am I missing a setting? I cannot get FMPA to stay at 12.5.

 

[BM82557]

Running Fastlane 2.212 with an Airspy in single SDR mode tracking a P25 system. I set the bandwidth to 12.5 in the FMPA-CC batch file, and it starts correctly. However, once I execute the 1Ra batch file and it tunes voice traffic, the bandwidth in FMPA changes to 9.5

Is this normal or am I missing a setting? I cannot get FMPA to stay at 12.5.

The bandwidth lock option (-b- (bandwidth lock)) that is used with FMP24 does not work with FMPA, I wish it did.

 

[msingewald]

So, would this count as a bug or feature? I ask as I don't know if I should email the DSDPlus guys or wait and see if they address this post.

 

[BM82557]

I have just emailed them about this issue

 

[msingewald]

I found in the notes where it says that it is chosen automatically based on protocol. Maybe 9.5 does better than 12.5 on P25.

 

[GTR8000]

I found in the notes where it says that it is chosen automatically based on protocol. Maybe 9.5 does better than 12.5 on P25.

P25 FDMA control/voice uses 9.5 kHz, P25 TDMA voice uses 12.5 kHz. If you watch the spectrum display in FMPx, you will see that the correct filter choices are being made automatically, there is no need to force or lock anything.

 

[BM82557]

For some P25 Phase I systems I have found that 12.5 produces better sounding audio on the voice freqs, 9.5 on the control channel does a good job.

 

[poltergeisty]

I have found that if the bandwidth is too wide you get interference from adjacent voice channels and thus an improper decode. So 12 to 9 is what I'd use.

 

[BM82557]

P25 FDMA control/voice uses 9.5 kHz, P25 TDMA voice uses 12.5 kHz. If you watch the spectrum display in FMPx, you will see that the correct filter choices are being made automatically, there is no need to force or lock anything.

This is just my observation, using FMPA on a P25 Phase II system (one receiver mode) the BW is 9.5 on the control channel and switches to 12.5 on voice channels as GTR describes, using FMPA on a P25 Phase I system (one receiver mode) the BW is 9.5 on the control channel but does not switch to 12.5 on the voice freqs, it stays at 9.5 as per protocol.

As I posted above for some P25 Phase I systems I have found that 12.5 produces better sounding audio on the voice freqs, 9.5 on the control channel does a good job. It might just be reception, IDK.