Dear Alberto, LF Group,
I recorded a .wav file of the SAQ broadcast yesterday. I checked
the frequency using Spec Lab, and the calibration factors I use for
Wolf reception. The frequency wobbles around slightly - it was
about 17.220kHz +/-5Hz. A distinctive feature of the SAQ signal is
the backwave - with the key up, the TX power is only reduced by
about 20dB, not completely eliminated. At my QTH this is audible,
and shows up as a rather drifty carrier on the spectrogram. The
backwave frequency was about 10-20Hz lower than the main
signal.
Incidentally, the error on the sampling rate of my soundcard is -
0.56% with 8kHz sample rate, +0.41% at 11k sample rate. So
errors of this sort can arise due to the soundcard alone.
Cheers, Jim Moritz
73 de M0BMU
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