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Some questions regarding band-pass filters

Could some electronics guru please provide some hints to my queries. For a 'four-times' carrier frequency recovery scheme, as used in QPSK, the QPSK signal is fed into a 'power-4' circuit, that outputs the fourth power of the input QPSK signal. This output is fed into a band-pass filter, whose center frequency is 4 times the frequency of the QPSK carrier signal. A band-pass filter obviously has a bandwidth - so in this case, how should the output of the bandpass filter look like ? Any hints, suggestions would be useful. Thanks in advance.

Reply to
Daku
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Why, like a sinusoid at four times the carrier frequency, of course. What else could it be?

Jeroen Belleman

Reply to
Jeroen Belleman

I'm not familiar with that scheme, but rectification of the data followed by a high-Q bandpass is a common clock recovery scheme. IIRC, they use a biquad. The bandpass output and lowpass output are in quadrature, which should give you enough edges.

Reply to
miso

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