Impulse Window Question

[ernperkins]

I recently made the plunge and purchased Omnimic (SW ver 4.68). I've used HolmImpulse for the last couple of years, but thought I'd give Omnimic a try after reading all the glowing reports. I've given it a test run and have two questions:

- Is there any way to adjust the vertical scale in the impulse window? I'm having trouble seeing my initial reflections after Omnimic autoscales the window. Being able to enlarge the impulse window would work too.

- When I select a gated measurement by clicking in the impulse window I don't get the response I expected. For example, when I click on 4 msec I expected the graph to start at 250 Hz ( 1/ (4 msec) = 250 Hz). However, the graph starts much higher, around 600 Hz IIRC.

Thanks,
Ed ( the "e" in ernperkins)

[killa]

Re: Impulse Window Question

I also noticed this. I also used Holm previously.

Not exactly an answer, more like a work around. But I just move the gating around from a short gate to a progressively longer gate and watch the fr for changes. As long as the FR doesn't get too rough the gating is fine. Of course how rough it is allowed to get is up to you.

[dcibel]

Re: Impulse Window Question

I recently made the plunge and purchased Omnimic (SW ver 4.68). I've used HolmImpulse for the last couple of years, but thought I'd give Omnimic a try after reading all the glowing reports. I've given it a test run and have two questions:

- Is there any way to adjust the vertical scale in the impulse window? I'm having trouble seeing my initial reflections after Omnimic autoscales the window. Being able to enlarge the impulse window would work too.

- When I select a gated measurement by clicking in the impulse window I don't get the response I expected. For example, when I click on 4 msec I expected the graph to start at 250 Hz ( 1/ (4 msec) = 250 Hz). However, the graph starts much higher, around 600 Hz IIRC.

Thanks,
Ed ( the "e" in ernperkins)

There is not any adjustment on vertical scale for the impulse. Use a tweeter to determine the first reflection, the first reflection is usually pretty well defined and is the only reflection of interest.

When you set a gate of 4ms, 250Hz is the gate freq but is also your resolution for the first octave. Resolution doubles every octave above the gate frequency, so my assumption would be that the Omnimic is only interested in showing you useful data, 1 octave resolution at 250Hz isn't accurate or useful information.

[ernperkins]

Re: Impulse Window Question

Thanks for the the feedback, it also explains some of the problems I had with HolmImpulse.