H-CPM demodulation using SDR

[panoboy]

Is there any SDR software which can demodulate H-CPM?

If not, are there unique challenges which make this difficult or is it due to a lack of interest?

Thanks.

 

[boatbod]

I think Max played around with it on his op25 for a while, but not sure he ever got it working properly. One of the challenges is that it is only used on the uplink side of a phase 2 system, so the overall range is limited (low power compared to a base station), and it is tdma burst transmission so designing a demod to quickly lock (and stay locked) is problematic.

 

[merlin]

I cant imagine why someone would have interest in H-CPM. There is no information in that modulation.
What it does is synch P2 fo non linear amplifiers making it compatible with P1.

 

[panoboy]

I think Max played around with it on his op25 for a while, but not sure he ever got it working properly. One of the challenges is that it is only used on the uplink side of a phase 2 system, so the overall range is limited (low power compared to a base station), and it is tdma burst transmission so designing a demod to quickly lock (and stay locked) is problematic.

Thanks for the detail, much appreciated.

Also, thank you for dsd-fme, I am playing with it for the first time. Nice work and the name cracks me up.

 

[panoboy]

I cant imagine why someone would have interest in H-CPM. There is no information in that modulation.
What it does is synch P2 fo non linear amplifiers making it compatible with P1.

I believe the information in H-CPM is the voice and data transmitted by the SU.

If I'm wrong here, anyone please jump in and correct me so I don't waste a bunch of time.

I was doing great demodulating C4FM from the SU in a P1 system, then I had to work within a P2 system and everything stopped. This is the first time I've had to work with a signal type that didn't have an existing SDR demodulator and it is becoming a serious challenge. Standing on the shoulders of giants is easy to take for granted until you have to do some of that foundational work yourself.

Thanks for the reply.

 

[boatbod]

I believe the information in H-CPM is the voice and data transmitted by the SU.

Yes, that's exactly what it contains. H-CPM is the uplink modulation from SU to RFSS