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Bandlimited pink noise plus a tone

PostPosted: Wed Sep 30, 2020 4:40 pm
by suktan
I want to generate a signal consisting of bandlimited pink-noise and a low-frequency sin in MI signal generator. It seems that I need to use a wav file for that. Direct generation of such composite signal doesn't seem possible. Is it correct?

Re: Bandlimited pink noise plus a tone

PostPosted: Thu Oct 01, 2020 12:36 am
by VirtinsTech
A band limited “periodic” pink noise can be generated using the Multi-tone function of the Signal Generator in Multi-Instrument, as shown as follows. (Align To = FFT, Frequency Response = Pink Noise, Frequency Range is user defined)
BandLimitedPinkNoise.png (17.89 KiB) Viewed 2816 times

If you want to use the above signal as the carrier frequency and modulate it with a low-frequency sinewave, you can use the Mask (Gated Window) function of the Signal Generator. For example, if the modulating frequency is 4Hz, then set the Mask On duration to 0.25 s and the Mask Off duration to 0 s. For amplitude modulation, Hann Window should be used. For intensity modulation, Cosine 1.0 Window should be used.

LowFrequencySineModulation.png (20.12 KiB) Viewed 2816 times

Re: Bandlimited pink noise plus a tone

PostPosted: Wed Oct 07, 2020 9:18 am
by suktan
Thanks for your reply.

I need to have bandlimited pinknoise and a low-freq tone in an additive way (A+B). Is it possible to do that internally in MI?

We currently can't have CHA (multi-tone, automatic) and CHB (multi-tone, manual) or CHB (not multi-tone). Can't it be changed in future release?

Re: Bandlimited pink noise plus a tone

PostPosted: Fri Oct 09, 2020 12:18 pm
by VirtinsTech
Could you shed some light on the use of this special signal?

There is a workaround. You can open two instances of Multi-Instrument and generate different signals from them. If Sound Card MME driver is used, the two generated signals will be mixed (+) by the mixer.

Re: Bandlimited pink noise plus a tone

PostPosted: Sun Oct 11, 2020 11:43 am
by suktan
I need pinknoise with high-pass at 150 Hz together with a < 10 Hz tone (known as pilot tone). The signal is used to power test loudspeaker drivers. The tone in low-level is used to measure coil resistance. My audio interface uses ASIO driver.

I was thinking to mix the two signals externally (e.g. op-amp ckt or miniDSP box) if CHA multi-tone pinknoise and CHB 10 Hz tone is possible.