How to get impulse response from analog devices?

 

Last edited: Apr 11, 2024

Impulse response is the output of a system when its input is a delta function. It is a useful tool for characterizing the behavior of a system, as it can be used to determine the system's gain, bandwidth, and other properties.

There are a number of ways to obtain the impulse response of an analog system. One common method is to use an impulse generator to apply a delta function input to the system and then measure the output using an oscilloscope.

Another method for obtaining the impulse response of an analog system is to use a network analyzer. A network analyzer is a device that can be used to measure the frequency response of a system. By measuring the frequency response of the system, it is possible to obtain the impulse response using the inverse Fourier transform.

Here are the steps on how to get the impulse response of an analog system using an impulse generator and an oscilloscope:

1. Connect the impulse generator to the input of the system.
2. Connect the oscilloscope to the output of the system.
3. Set the impulse generator to generate a delta function pulse.
4. Set the oscilloscope to trigger on the leading edge of the delta function pulse.
5. Capture the output of the system on the oscilloscope.

The impulse response of the system will be displayed on the oscilloscope.

Here are the steps on how to get the impulse response of an analog system using a network analyzer:

1. Connect the network analyzer to the input of the system.
2. Set the network analyzer to measure the frequency response of the system.
3. Measure the frequency response of the system.
4. Use the inverse Fourier transform to obtain the impulse response of the system.

The impulse response of the system will be displayed on the network analyzer.

What is your method?

 

Last edited by a moderator: Apr 11, 2024

It's been a while but we needed to mimic a particular and peculiar acoustic space for some post production work, so what we did was just the basic stuff: get a playback system, we used a single KRK monitor for this, hooked it up to a laptop and used a synthesized noise sweep. Then we set it up to the rough location, used a simple Rode mic and hooked it up to the laptop as well. It was a used building so we had thankfully access to electricity with some extension cables.

Then we made several recordings, something play/record like 3 sweeps, adjust the listen and playback positions slightly, redo. Then hit the pub, done.

Afterwards edit the recordings, keeping the sweep and the recording lined up as per the setup, deconvolve using Space Designer. Find out the best one for some vocal line dubs. Done.

It didn't have to be *perfect*, just in the ballpark so it wasn't like it was the recreation of a cathedral or anything.

 

an oscilloscope does not measure anything and measuring something does not give you a digital file.

no idea why you would need visual feedback at all to record something. except the peak. ;)

and while an ifft is surely part of the process, it is not identical to an ifft, which on its own and outside of an fft context it does not make any sense.

what can get tricky in practice is to decide whether you should bandlimit the impulse before you run it into the unit or only before digitalizing the response. and of course when sweeps are better than impulses.