Hi A.J.,

Thank you for the reply. After checking out the interface again, all the necessary parameters for diagnosing P25 do indeed seem to be there, albeit slightly different nomenclatures for general (X)FSK.

RMS Deviation Error = RMS FSK Err(%)
Frequency Error = Carrier Offset
Symbol Deviation = Average Deviation

A Filter Alpha of 1 will work best with C4FM. The only thing which is lacking for complete analysis is the Symbol Distribution Table (reference in my video link). With the addition of that, it would be complete for P25 troubleshooting.

Great work so far, and very glad to have this added functionality in Spike!

Rob

I see that 4FSK had been added to Spike 3.0.13. C4FM is only a short step away! Still patiently waiting 🙂

Btw, here’s a good presentation from Aeroflex on the standard and implementation of C4FM:

Aeroflex C4FM

Thank you A.J., I look forward to seeing that functionality! 🙂

Bruce, loving the new 3.0.8 update of Spike with the Digital Demod analysis! This is frankly what I was waiting for. Do you think a future version could include C4FM (APCO P25) analysis? This is a hugely implemented voice standard and digital modulation method employed in both commercial and state Public Safety communications all over the world, and is ever-expanding and growing into the non-commercial/consumer market everyday. Would love to see it in a future version of Spike! 🙂

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