AFMG Network Forum

Greg L · Member

To All,

Would TFC be best used with sweeps that start high and go low?

I may be missing something, but when using TFC, the small hi-freq window will cut off all the high freq part of the sweep...

Additionally, it would be nice if Easera could also generate these sweeps, and hence one could have use narrow band sweeps if desired.

Lastly, why do the sweeps not last for the full, or at least a larger part of the signal period?

TIA,

Greg

Charlie · Member

Hi Greg,
I'm sure Bruce, Stefan, or others from AFMG will jump in and correct me if I'm wrong, but I don't think the window, be it a TFC or conventional, is applied to the sweep as its acquired (recorded). The sweeps from the System Under Test are recorded and from this an impulse response in derived. The window is then applied to this IR to remove or minimize the effects of reflections on the measured data. The windowed IR can then be used to calculate the response in the frequency domain.

Doug Fowler · Forum Moderator

Greg -

A window will be applied to the incoming data stream if "Use Window before FFT" in General Options is checked.

I was using internally generated sweeps last week and noticed the magnitude response changed (phase too :-) in time with the sweep frequency.

Hmmm......

It turns out I had "Use Window before FFT" checked.

FWIW

-doug