Hi all, I have a question please? I have an input signal with 1.5 Mhz sampling rate. I have a serial of FIR filters which are used to interpolate this signal. The first filter interpolate the signal by 2 which works on 3 Mhz, the second one interpolate the signal by 1.5 which work on 4.5 Mhz. Could you tell me please how can I calculate the group delay of the overall system. I have an idea so that I can calculate the overall transfer function of the system than calculate the group delay of the overall system. But I am not sure if that way is right because I have two filter which they running with different sampling frequency? does any one have another idea? do you think the calculation which I do to calculate the group delay is right? Thank in advance, RDDSP
Group Delay of Multirate multistage system
Started by ●August 20, 2012
Reply by ●August 20, 20122012-08-20
Hi, you'd calculate it for each stage at its respective rate. Or: take an impulse [1 0 0 0 0 ...] sequence, run it through your chain. Use enough samples so you get zeros at the end (it's FIR, after all). Then use Matlab's groupdelay() function on the resulting impulse response. Which is the impulse response for the whole chain. The result is in units of samples at the output rate.