RE some of the two tone plots from reading the links:
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I found with my experiments with a Teensy version of the usdx from the qcx board that a two tone test does not test the entire polar modulation algorithms but only the AM modulator half.? The frequency generated is constant.? So I think it is a poor test for the entire radio but an excellent test of the modulator.
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I digitally generated perfect amplitude tones skipping the audio A/D and sampled digitally at the output of the hilbert, square root algorithms writing data to the arduino plotter.? The discontinuities in the below result is from capturing some real time data in a burst and then skipping taking samples while writing to the plot.?? The constant frequency is 1000 hz, half way between 700 and 1300.
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