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Sampling ultrasonic signals

JPolo

New Member
Hi,
I want to sample 4 audio sources which frequencies would be between 30 kHz and 40kHz (ultrasonic signals). Is there a microcontroller with ADC that could do that?
 

gophert

Well-Known Member
Most Helpful Member
Hi,
I want to sample 4 audio sources which frequencies would be between 30 kHz and 40kHz (ultrasonic signals). Is there a microcontroller with ADC that could do that?
Assuming you have 1,000,000 samples per second, you can, in theory, get 6 samples from each of the four channels for each wave length. So, in theory, you'll be able to identify a frequency with just 6 data points but not resolve any wave features.

Unfortunately, that 1M/sec is the number of samples off of a single channel of an ADC chip. Each time you switch to a new channel (to get each of the other waveforms), you need a "settling time". Look for settling time info on the ADC datasheet. If your settling time is in the range of a microsecond, you'll only resolve 1.5 data points per waveform which means you'll no longer be able to resolve frequency of the signals. Settling time is likely below 1microsecond but I recommend faster than 1Mps ADC. Also, you'll need a reasonably fast microcontroller to manage the data.
 

ronsimpson

Well-Known Member
Most Helpful Member
Do you need to know the relationship between the four signals? (Phase)
If so you need to sample all four at the same time. If not, then sample one at a time.
What do you need to know about the signal?
 

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