#### Eugen_E

##### Full Member level 6

I need to measure the phase difference and amplitude ratio of 2 signals of equal frequency (~1kHz), afected by noise and harmonics. The signals are sampled by soundcard on channels L and R, then filtered by a few bandpass biquad cells at 1 kHz.

I imagined 2 methods for measuring this:

1. Shifting a signal by 90°, multiplying with the other signal and obtaining the I and Q components, then filtering and computing the phase difference. The amplitude ratio can be estimated?

2. Doing a sine fit on both filtered signals, then obtaining the amplitude ratio and phase shift.

I never did this before but I found references on sine fitting for ADC characterization (only papers, no sample code ), and the joint fitting of the signals seems difficult.

What is your oppinion about these methods regarding speed and precision, low SNR performance... ? 2. has a big advantge?

Thanks