I've exported a set of measurements as text so that I can analyze them using Matlab. I'm running into trouble extracting an impulse response from the magnitude and phase data that are exported.
To be sure I had my ducks in a row I first simulated an impulse in Matlab and added a bit of noise. I used an fft to compute a two-sided complex spectrum, extracted a single-sided spectrum, and then calculated magnitude and phase from that. I was able to reverse those steps and start with the magnitude and phase, recreate a two-sided complex spectrum, and use the inverse fourier transform to compute the impulse response. It matched perfectly with the starting point.
If I use the same reversed steps when starting with exported magnitude and phase data from REW, the impulse response is unrecognizable. I can post a graph if it would be useful; it amounts to lots of positive and negative spikes near t=0 and at the end of the time sequence, with a bit of a quiet period in between. Certainly nothing close to an impulse.
Am I missing something about the data exported by REW? Could someone please give me a very brief description of the way REW computes an impulse response from the magnitude and phase data?
Many thanks.
Few
To be sure I had my ducks in a row I first simulated an impulse in Matlab and added a bit of noise. I used an fft to compute a two-sided complex spectrum, extracted a single-sided spectrum, and then calculated magnitude and phase from that. I was able to reverse those steps and start with the magnitude and phase, recreate a two-sided complex spectrum, and use the inverse fourier transform to compute the impulse response. It matched perfectly with the starting point.
If I use the same reversed steps when starting with exported magnitude and phase data from REW, the impulse response is unrecognizable. I can post a graph if it would be useful; it amounts to lots of positive and negative spikes near t=0 and at the end of the time sequence, with a bit of a quiet period in between. Certainly nothing close to an impulse.
Am I missing something about the data exported by REW? Could someone please give me a very brief description of the way REW computes an impulse response from the magnitude and phase data?
Many thanks.
Few