Sampling ultrasonic signals

[JPolo]

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?

 

[dknguyen]

They all can. 1Msps is standard

 

[gophert]

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]

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?

 

[Wade Hassler]

Do you need to preserve frequency information of the signals? . That is, are they passed through an envelope detector?