Re: [SpectrumLabUsers] PAM-Validation
- Hello Christoph and group,
Thanks for the detailed examination - it's encouraging to hear someone is making good use of the phase / amplitude monitors, and this will certainly motivate further development.
Especially the GPS-PPS timed synchronisation, which I am currently working on, may be a way to eliminate the phase glitches. With the PPS signal, the program could detect missing samples from the soundcard (which does happen from time to time, usually depending on the CPU usage), and correct the phase readings. The new principle (which is currently "under construction") first resamples the input to a very precise, and highly phase-stable sampling rate. With the GPS sync signal, "lost" samples can be detected, and filled up by silence to restore phase coherent detection. Actually, this makes the phase detection simpler than it is at the moment, and possibly even more efficient with weak signal/noise ratios.
Have a nice weekend,
Am 31.03.2012 16:05, schrieb Christoph Maurer:
As mentioned earlier, I am now uploading a small comparison between the
PAM-function in SpecLab and another program (UltraMSK), since I thought
you might be interested. NAA (24 kHz sending from the North American
Eastcoast) and NRK (37.5 kHz from Iceland) are best suited as examples.
UltraMSK uses a GPS-PPS-signal for timing, Speclab uses the
Interesting are the second and third panels. The red line is the
UltraMSK output, the blue dots is Spectrum Labs output. It looks very
similar, although Spectrum Lab tends to exhibit phasejumps. Some might
stem from the timesignal, since they are consistent for all transmitters
(The double jump between 1 and 2 o' clock). Some might not (the 16:30
jump of NRK is not visible in the NAA plot). Also, UltraMSK seems to be
a bit more proficient in measuring the phase of weak signals (as can be
seen in the interference minima of NAA)
Long story short: It works! Thanks again especially to Wolf for helping
with the configuration.
Christoph Maurer B.Sc.
Technische Universität Darmstadt
Institut für Kernphysik
AG Strahlen- und Kernphysik
Tel.: (+49) 6151 16 4426