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Excitation Signal/Direct IR
PostPosted: Tue Jun 23, 2015 2:28 pm Reply with quote
Niick
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Joined: 07 May 2015
Posts: 25
Location: Portland, OR USA




I'll admit that I haven't spent a lot of time attempting to use sweeps as the excitation signal, however, when I did try it, I didn't get a stable, full bandwidth trace as a result. Was I just not using enough averaging, or maybe the exponential averaging mode with the decay time constant set to roughly the sweep time is the way to go?

I've read that the sweeps are better for certain things, maybe S/N ratio? If so, what are some advantages and disadvantages to using sweeps instead of noise? I know......"read the manual!!" It's just that it seems the manual doesn't go too terribly deep into this topic, and since annoying bystanders isn't really a concern with me, (due to the fact that my measurement environment is a closed automobile) I was wondering if there are any inherent, real world advantages to using sweeps.

Also, is it possible to directly capture an IR in SysTune, like with a balloon pop? And then take the FFT of that captured IR?
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PostPosted: Wed Jun 24, 2015 8:41 am Reply with quote
Waldemar
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Joined: 05 Dec 2005
Posts: 112




Hi Niick,

if the measurement conditions are excellent, the result must not rely on the used signal!
We recommend to use sweeps (best log-sweep), if the noise is not white, that means there are multi-tones in the noise, or if there is not negligible distortion (which cannot be omitted) while measuring.
For Log Sweep the distortions are collected at the end of the Impulse Response, where they can be windowed out easily.

You can record a balloon bang with a recording tool (like EASERA or the Windows recorder). This (can be .wav-) file can be loaded in SysTune and used to show the transfer function (FFT).

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SDA, Waldemar Richert
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