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Measurements >> Phase Noise and Jitter Measurements >> how to do pm-demodulate in spectre?
https://designers-guide.org/forum/YaBB.pl?num=1116160656

Message started by jfyan on May 15^th, 2005, 5:37am

Title: how to do pm-demodulate in spectre?
Post by jfyan on May 15^th, 2005, 5:37am

hi all:

a pm-modulate siganl,e.g x(t)=a*sin(wc*t+Asinwm*t), if i want to extract Asinwm*t, how can do in spectre?
one approximate way is to look at the zero crossing times of the x(t) and compared in with the carrier signal,
but i don't know how to write down the zero crossing time points in spetre, so need you help!

thanks in advance

Title: Re: how to do pm-demodulate in spectre?
Post by Eugene on May 15^th, 2005, 2:58pm

There may be some new Spectre feature that lets you direclty extract the phase modulation but I can think of two other ways that might work.

1. You could use a phase detector. One way or another you would have to filter a ripple component. You might even try a complete PLL. The filtered phase detector output should track the modulation if the filter is properly designed.

2. IF you have SpectreRF, you could do an Envelope Following analysis and plot the phase of the first harmonic of the carrier. I don't remember if the phase is directly accessible from the output form. If it is not, you might have to plot real and imaginary then use the waveform calculator to compute the phase.