Decoding APCO P25 with RTL-SDR dongle

[N1KK]

I'm interested in using a RTL-SDR dongle to decode APCO P25 I and II. I have used a cheap RTL-SDR and something more expensive like a SDRplay. With both the quality of APCO P25 was poor. This was done with a Windows i7 laptop running SDRsharp and DSD+
Would there be any better quality using a Raspberry pi, same SDR but linux software? What combo of Raspberry pi, SDR and software has become the best for APCO. My Windows setup worked well for DMR but it poor for APCO P25. Thanks, Ken

 

[a417]

Define 'poor'? (and don't hijack threads)

I use OP25 on Linux, and DSD+ on WindowsXP (and a VM), and Windows10, and I can say that they all decode nearly exactly as well as each other...when they're fed a good signal. I can guarentee you that you will get better results using FMP24 to feed DSD+ (that's why they tell you to use it, not a hack plugin) than what you are using now.

You need to use one suite to its full effectiveness & utility before you throw baby out with the bathwater.

Ditch SDRSharp, use DSD+ with FMP24 and then you will see exactly what your problems are. I'll be willing to bet that it is signal strength & configuration , not the underlying OS & host hardware.

 

[boatbod]

On linux you can't beat op25. For windows it's DSD+ FL.

 

[N1KK]

Thanks for all your replies.
Any particular RTL-SDR known to work better than others?

Thanks,
Ken

 

[DRL-XM43]

SDRTrunk for Win and Linux and MAC

 

[slicerwizard]

Orange FlightAware Pro Sticks have better 400+ MHz sensitivity.

 

[AB5ID]

Get a RTL dongle with a TCXO for good frequency stability.

 

[TheButcher]

a) Good outdoor aerial (no need to define 'good'!)
b) On frequency (see AB5ID's post)
c) Appropriate gain set for recieved signal strength (set to '0' if very, very strong), no more than say, 30 for weak signals, averaging about 16 (is good)

Um, that's about it. I am sure I am forgetting something. I hope I am on topic here...
I like to have top of bell-curve in FMP24 set between 1/3 and 3/4 (less than say 1/10 or 2/5 leads to poor reception). And watch the spectrum readout for overloaded front-end of rx, which is possible in (RF) noisy environments, or if bloomin' gain is set too high (normally above 30 / 40).

About 1/2 to 3/4 is optimal with gain at say, 16. This is not always possible etc, etc, etc. I hope this helps DSD+ Users!

A screen shot / grab of FMP24 is always helpful here. Oh and please don't run indoor aerials peeps!