Sampling Hz increase 8

[FeX32]

Hey guys,

I have a straightforward question.
I have a DAQ system that can sample at 10,000 Hz max. I now have an application that requires 20,000Hz sampling.
There are several unused ports on the DAQ system. Is there a way to obtain an effective sampling of 20K Hz with the current system? Or an approximate method? Thanks,

Fe


"Simplicity is the ultimate sophistication." L. da Vinci
- Gian

 

[VEBill]

Counting revolutions (or a fraction of a revolution) per unit time versus counting units of time per revolution (or fraction of a revolution) will each give best measurement resolution under more-or-less the opposite circumstances. Always consider both approaches to see which one fits your requirements. And confirm the numerical resolution.

An "impossible" measurement might become trivial with the inverse approach. Or more accurately, using the wrong approach may make a relatively simple measurement impossible.

Of course, one could even do both schemes in parallel if required.

 

[MacGyverS2000]

At those low frequencies, I would think a 4:1 downcounter would be very easy/cheap to put together (proto board) and give you the signal you need. Unless you have simple access to the current geartrain and can modify it, things would likely be easier in the digital domain.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[FeX32]

I agree Mike. I will fr sure have to read up on a few things. Also, true regarding the IC engine crank sensor. Thanks.

Thanks for your input Gunnar. That article may come in handy. Simply counting the number of revolution in a set time period will do the trick. I will have to try and correlate each of these intervals to obtain accel too.

VE1BLL, I think for this application counting number or revs in a time period may be simpler. But I can consider both for sure.

Dan, Thanks. I am unfamiliar with an electrical downcounter. I can consider it too however.

Happy Easter to everyone.

 

[IRstuff]

Downcounting is the electronic version of gearing down. Typicalling, a conventional binary counter can count much faster than a processor could record the data, so a prescaler would do something like a modulo-4 count, and the output of that would be counted by the processor.

TTFN
faq731-376

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[FeX32]

Thanks IRstuff!

 

[VEBill]

"...counting number [of] revs in a time period may be simpler."

In that case, one is dealing with low MHz signals. Trivial. One needs to balance update rate with numerical resolution (1s = 1 ppm, 1ms = 0.1%). And there are ways to blend and balance both.

--

Previously: "...would like more than one sample per revolution to measure small variations in angular acceleration."

Which is where the opposite approach would perhaps have been better.

 

[FeX32]

Indeed VE1BLL! Thanks