<?color><?param0100,0100,0100>Dear Mike, LF group,<br><br>G3XDV wrote:<br>><?/color>My understanding is that for voice transmissions NBFM and >phase mod are differently achieved but result in roughly the same >mathematics so can be demodulated as if they were identical. <br>>In the same way, can we achieve the same effect as PSK by >doing something with the frequency instead? If so, linearity is not >an issue.<br><br>That's exactly what my prototype circuit is aiming to do. So far, it demonstrates that BPSK-like signals with constant amplitude (and therefore not requiring a linear amp) can be generated with acceptable sidebands using a phase modulator. These signals could be viewed mathematically as either phase- or frequency modulation. However, to obtain the benefits of coherent signal detection, it is neccesary to preserve a definite fixed relationship between the phase of the modulated signal, and a reference phase (the carrier). Practical p hase modulators do this, but practical analogue frequency modulators (basically voltage controlled oscillators) don't.<br><br>So far so good, but now the question is are these phase-modulated signals compatible with BPSK as far as reception is concerned? That's the next stage in the experiment....<br><br>Cheers, Jim Moritz<br>73 de M0BMU<br><br><br>
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