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Appendix
After several comments were received and in light of the ongoing discussion
on the PSK31 reflector I thought it might be informative to add the
following spectrum analyzer and oscilloscope pictures.
The spectrum picture shows a single tone spectrum compared to a BPSK
spectrum. These are accurately portrayed in that the power levels are
the same for the single tone and each of the shifted BPSK carriers and
these represent average powers. The oscilloscope picture on the other
hand shows the reason for backing down the average power in that the peak
envelope voltage is 6db higher than the peak voltage of the single tone
carrier. The peak envelope power is therefore 3db higher - thus the
recommendation to adjust the BPSK idle condition, which is shown in these
pictures, for approximately ½ or -3db down from the single tone carrier or cw signal. Now, the only question remains is
where does your rig begin distorting the signal.
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