04-12-2007 07:54 AM
04-13-2007 02:12 AM
What signal are you dealing with??
is it an analog signal?? ( sinsusoidal, triangular, etc)
Or is it a TTL pulse??
04-13-2007 03:11 AM
04-13-2007 04:58 AM
04-16-2007 09:33 AM
04-17-2007 07:51 AM
read these 2 links and see which of methods would be best for your purpose
http://zone.ni.com/reference/en-XX/help/371361B-01/lvmeasapps/meas_analog_freq/
04-17-2007 08:09 AM
eesen,
What you are doing doesn't make any sense to me. First of all, you should take multiple samples with the DAQmx Read and not one sample at time with the timed loop. Your frequency measurement will then actually be more accurate. You also should return a waveform. That includes timing information that the Freq & Amp function needs to determine the frequency. It cannot do it with a dbl array. If you have to display a dbl, then just use the Get Waveform Components to extract the y array. You can get rid of the second timed loop and use a regular loop for the DAQmx Read. If you just set the rate to be twice the highest input frequency and acquire enough samples for a couple of cycles, you should have a pretty accurate reading.
04-18-2007 09:06 AM
Thanks for repplies. You give good points about frequency measurement, but advices gives no help for my real problem.:(
Let say i get rid of second loop and read samples as waveform. This doesn't solve my problem? I think, measuring frequency using anolog input channel in real time is not possible by software.
04-18-2007 09:27 AM
04-19-2007 03:30 AM
I started with shipping examples. Since shipping examples don't satisfy my needs, i try to find another solution.
Thanks