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Topic: Looking for an audio signal function generator... (Read 893 times) previous topic - next topic

holesflow

Mar 28, 2018, 02:57 am Last Edit: Mar 29, 2018, 07:33 pm by holesflow
Experts,
As for standard signal generators, the higher the frequency, the more expensive. And for other things, that is great, but not the functionality I need in an arbitrary signal generator. With all the RF/signal functions, I'm looking for a generator that can [also] do audio (0~40kHz).

Specifically, has anyone come across a generator that can do all the normal kinds of "noise", or sweeping, or only outputting sweep/noise from/to specific frequencies? There are other things, like mixing a spike/harmonics with noise, overlapping or even adding signals, and I can see needing mixing (though I can do that with standard audio mixers I have).


While I can always use a sig gen in the high MHz for my bench, I seem to do a lot with microphones/FFT/FHT, etc. lately. Do I need 2 separate generators, or can one get both types in a single box for ~$300 USD?


TIA!
"A wise man can learn more from a foolish question than a fool can learn from a wise answer". ~ Bruce Lee.
"If you drop it and it breaks, it was good." ~ Mr. William Lehr, my Electronics VoTech Teacher, on testing vacuum tubes. RIP

DVDdoug

Did you Google "audio signal generator" or "function generator"?   I'd expect one with all the features you want to be expensive...

Audacity can generate sine, square, and sawtooth waves that you can play with your soundcard.  You'd have to write a program in Nyquist (a language used by Audacity) if you wanted a sweep or other wave shape.

Or you can probably find an audio generator application, or an app for your phone.  (But of course, the waveforms will be quantized and then filtered by the DAC so they won't be "perfect".)

ard_newbie


A DUE has 2 built in DACs and a True Random Number Generator. With the TRNG peripheral, you can generate white noise and output it on one or 2 DACs, and by doing some math with the core, you can generate any wave form you want to output at e.g. 44.1 KHz or higher.

MarkT

While I can always use a sig gen in the high MHz for my bench, I seem to do a lot with microphones/FFT/FHT, etc. lately. Do I need 2 separate meters, or can one get both types in a single box for ~$300 USD?


TIA!
What meters are you talking about?
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

MarkT

Specifically, has anyone come across a generator that can do all the normal kinds of "noise", or sweeping, or only outputting sweep/noise from/to specific frequencies? There are other things, like mixing a spike/harmonics with noise, overlapping or even adding signals, and I can see needing mixing (though I can do that with standard audio mixers I have).
For audio use certain things are very important that are less relevant for RF work.

Low distortion is needed for THD measurements (for audio work this typically means 0.01% or better, way beyond what's needed for general purpose oscillator)

Two tone generation is needed for intermodulation measurements, again with very low distortion.

Noise generation (white and pink) and sweep generation (log and linear) as you mention.

Sounds cards can be very useful, but you won't get to 40kHz unless you have one that
can run at 96kSPS and has configurable output filter.

[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

holesflow

Did you Google "audio signal generator" or "function generator"?   I'd expect one with all the features you want to be expensive...

Audacity can generate sine, square, and sawtooth waves that you can play with your soundcard.  You'd have to write a program in Nyquist (a language used by Audacity) if you wanted a sweep or other wave shape.

Or you can probably find an audio generator application, or an app for your phone.  (But of course, the waveforms will be quantized and then filtered by the DAC so they won't be "perfect".)
Thanks DVDdoug! I've used Audacity (99% on Linux) for a long time, but never thought of hitting it's API!
"A wise man can learn more from a foolish question than a fool can learn from a wise answer". ~ Bruce Lee.
"If you drop it and it breaks, it was good." ~ Mr. William Lehr, my Electronics VoTech Teacher, on testing vacuum tubes. RIP

holesflow

What meters are you talking about?
Fixed OP. Meant "Generators". I hate it when the wife interrupts mid-post! :)
"A wise man can learn more from a foolish question than a fool can learn from a wise answer". ~ Bruce Lee.
"If you drop it and it breaks, it was good." ~ Mr. William Lehr, my Electronics VoTech Teacher, on testing vacuum tubes. RIP

holesflow

Thanks for writing, MarkT.
I'm not interested in precision for THD or frequency. I guess you could say I'm working with measuring and adjusting things like bandpass (LP, MP, HP) and frequency response. Simulating real world noise in some cases with a generator, then using other equipment to analyze & adjust to suit. 
So far I'm using speakers and basic desktop tools, but these are about as bad as you can get for this kind of thing-even for someone not overly concerned with accuracy. Plus it can get loud... :)
It would be great to just have a sig gen that got almost all of one's audio needs in one form factor. I mean, even sweep is a good start. I'm wondering how much functionality I can get for a few hundred bucks... Is anyone doing audio analysis/circuits? What are you using?
TIA!

For audio use certain things are very important that are less relevant for RF work.

Low distortion is needed for THD measurements (for audio work this typically means 0.01% or better, way beyond what's needed for general purpose oscillator)

Two tone generation is needed for intermodulation measurements, again with very low distortion.

Noise generation (white and pink) and sweep generation (log and linear) as you mention.

Sounds cards can be very useful, but you won't get to 40kHz unless you have one that
can run at 96kSPS and has configurable output filter.



"A wise man can learn more from a foolish question than a fool can learn from a wise answer". ~ Bruce Lee.
"If you drop it and it breaks, it was good." ~ Mr. William Lehr, my Electronics VoTech Teacher, on testing vacuum tubes. RIP

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