90-degree phase shift

Hello,

You could use two FIR filters in SigmaStudio, where the coefficients are calculated with a constant phase shift of 90°.

A good program to do this is SCOPEFIR5; with this program, the phase changes, but the phase difference is constant to the chosen value, ie. 90°.

Regards

Dany

Dany：

Thank you very much , but I still don't understand, can have a Examples can be for reference?

Hello,

It deprends also if your frequency is fixed or if you process speech, for instance.

1) if your frequency is fixed, or slowly variable, with constant amplitude, you can generate at 4 times the frequency and divide by two and again by two, thus giving you signals at 90° difference, taking the right taps.

2) if you process speech, with variable amplitude and frequency, you can use two low-pass or band-pass FIR filters covering the same frequency range, that may have a varying phase, graphically going down, thus going up in phase, towards 180° or more, but -and this is important- with a phase DIFFERENCE of 90°. This gives you the celebrated I and Q signals.

I hope to be clear; you may have to dig into the theory.

If others can explain this in a more pedagogic manner, please step in.

Ready to help again

Regards

Dany

I want to be with ADAU1701 to handle speech signal. The speech signal do 90 ° / 180 ° / 270 ° / 360 ° such a treatment, what a pity, English is not my native language, I can't very good understanding...

If there is one example I'll be more easy to understand.

Thank you again for your answer!

You need to goole for "hilbert transform filter", it is a FIR filter that gives you a 90 deg. shifted signal.

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