Re: tfestimate vs fft

[Arnaud Miege]

On 24 April 2013 14:48, Henry Gomersall <address@hidden> wrote:

The following is probably a good read in this context:
http://dsp.stackexchange.com/questions/2096/why-so-many-methods-of-computing-psd

Do you get a phase measurement from the tfestimate function? I'm a bit
rusty with these techniques, but it seems like a tricky thing to try to
extract.

As a heating device, I presume nothing changes very fast? It might be
enough to give it a blast of heat and then remove it. That could
reasonably modelled as a rectangular pulse with some arbitrary scaling.
I'm beginning to hesitate though as I'm not really a control engineer,
so trying to influence plants and suchlike is not my area.

hen

Thanks. I have just collected some data with a rectangular pulse input, so will see how well that fares. 

No, you do not get the phase directly from the tfestimate function, but you do get a complex number back so here is what I have done:

[mag_meas,freq_meas]=tfestimate(heater_ip,temp,[],[],nfft,Fs);

ph_meas = unwrap(angle(mag_meas));

ph_meas = ph_meas*180/pi;

Arnaud