service monitor questions

[kt2728]

Does anybody make a service monitor that will test the new kenwood digital format NXDN as well as p25 and analog?

I am in the market for a service monitor and just stared doing my research.

thanks

kt

[MSS-Dave]

General Dynamics R8000. Have one with P25 and DMR. NXDN is an option.
Even does analog....


Dave

[kt2728]

do you have any idea what kind of money are we talking about for an r8000?

[MSS-Dave]

An close estimate for what I got was slightly less than $30K. That was for P25 and DMR. I believe NXDN would add between 3 and 4K. Mine isn't Astro25 capabile but I believe it is available now. There were some other options that was bought in a package but I can't get to the order right now to see what they did.

[Wowbagger]

The Aeroflex 3900 also does NXDN, as well as P25, Smartnet, Moto P25 F2, analog, arbitrary waveform generation (so you can tickle a D-Star radio, for example), Astro25, and a few other things.

[MassFD]

General Dynamics R8000. Have one with P25 and DMR. NXDN is an option.
Even does analog....


Dave

Even does analog, thats funny LOL

[escomm]

Does NXDN need a digital monitor to tune? Sure don't need one for any Motorola P25 radio or TRBO.

[ve3ei]

This is primarily directed at Wowbagger, as he seems to know what he is talking about!
"The Aeroflex 3900 also does NXDN, as well as P25, Smartnet, Moto P25 F2, analog, arbitrary waveform generation (so you can tickle a D-Star radio, for example), Astro25, and a few other things."
How do you tickle a DSTAR? "Stroke its bits???"
Seriously, the question I would like to ask is how would you "see/view" (on a demodulator?) the DSTAR waveform to determine if it is balanced? or has FSK errors?
Basically, the same question for NXDN, which is FDMA C4FM?
The 2975 (that I have) does not do natively but could I use the CQPSK Generate/Receive and Analysis option for looking at that information/waveform?
Eric

[Wowbagger]

The 3900 can play an arbitrary waveform, so you can play a canned D* waveform and make the radio "talk". But the 3900 doesn't have the needed DSP code to demodulate and analyze a D* waveform to give you parametrics on it - we can tell you over-all deviation, carrier frequency, and TX power.

Just because something is "4FM" doesn't mean we can analyze it: we have to have the appropriate reconstruction filters, sample rates, interpolation filters, etc. to demodulate the signal, identify the sample times, regenerate the ideal waveform, and compare the two. So the 2975 and 3900 won't do NXDN demod analysis because they don't have the specifics on NXDN's form of 4FM.

Think of it like this: Narrowband FM, Wideband FM (in the LMR sense), and broadcast FM are all "FM" - but without knowing the preemphasis filters, the desired deviation, etc, you cannot automatically say Pass or Fail.

[ve3ei]

Thanks for the description and that makes sense. However, knowing the symbol frequencies of 350 & 1050 is there no way I can see those? Or would be able to see them on a spectrun analyser?

In your example of FM, with a Spectrum Analyzer, I can look at the signal and see how wide it is? Can I do something similar with C4FM? Or do I need a different monitoring device?

[Wowbagger]

You can look at C4FM on the analyzer

But no, there is no equivalent of a generic C4FM analyzer - you HAVE to be able to reconstruct the ideal signal, so you have to have a great deal of info about what you expect.