I have not seen the file you mention, but I would take an expanded look to the carrier frequency using Spectran before blaming Winrad.
I have seen some severe multipath and doppler spread that might very well confuse the PLL. I have recorded one case of some five threads moving sort of like snakes, in a 5 Hz bandwidth, fading, appearing and dissapearing, and with similar strenghts...where does the PLL should lock there? If the "carrier" it is using as reference to lock, fades, what happens? It must unlock and jump...There, the dynamics of the PLL play an important part, and as everything in engineering, there must exist compromise choices that do not always solve all the possible scenatrios...unless you go to multiple choices, which might be even more confusing to non experts. Multipath with doppler spread is a tough case for an ECSS detector. An envelope detector is much "nicer" then, but with the traditional changing audio response and distortion associated to diode envelope detectors. Possibly, a thereshold-less detector, or a mathematical procedure like extracting the square root of the squared value might "behave better" in a case as the one I describe. Comparing the ionosphere with a boiling water pot, the water - air boundary is constantly moving, and thus, the reflection / diffraction height is a varying one. If there are more than one reflection from multiple reflection points, locking to reflected/difracted doppler spread carriers with varying amplitudes is anything but trivial. The speed of "bubbling" in the ionosphere between two ionized gas regions is much slower than the boiling water example. Regarding to the LF response, I would like to have the lowest possible frequency cutoff available, 20 Hz might be a good choice, if it is possible to go that low. I have played short wave stations received with shifted tuning (carrier is not zero Hz, but about 500 Hz) and zero but tuning that with the older Winrads on USB gives BEAUTIFUL broadcast quality low frequency audio (disregarding the obviously missing high audio frequencies on a 2.7 kHz wide SSB filter). The effective bandwidth becomes 2.2 kHz or so, but with that peculiar broadcast studio sound, instead of the tinny sound of zero beat SSB with 300-400 Hz LF cutoff. 73, Jose, CO2JA ---- Alberto I2PHD wrote: > Bjarne Mjelde wrote: > > Alberto, > > when playing back an SDR-IQ file the frequency in ECSS appears to be > > very unstable even with a relatively strong signal. Changing rapidly > > with anything from a few to 20-30 Hz. > > > > Bjarne, > > thanks for the report. Could you please send me that I/Q > WAV file to use as a test to diagnose the problem ? > I checked here with both the SDR-IQ and Perseus but > I am unable to reproduce that behavior. > > Thanks > > 73 Alberto I2PHD
