high frequency measurement 2 counters range

[ASTDan]

Hello,

I know this info is somewhere but I can't find it.

When using a Counter/timer to measure frequency there are multiple methods.

i.e. Low Frequency with 1 counter and high frequency with 2 counters.

What is the definition of a "low frequency" and what is the definition of a "high frequency"?  i.e. low frequency = frequencies below 100 Hz 

Also what is the definition of a "large range"?

Thanks

Dan

[Jeremy_T]

Hi Dan

There isn't a specific bandwidth that is defined for use with either the one-counter or two-counter method. However, located in the NI-DAQmx help file there is a section detailing the quantization errors that arise when using either method with a variety of input frequencies. By referring to this information you should be able to determine which method will produce the smallest error in your application and hence which method will be preferable. This help file also explains the errors associated with the large-range two-counter method.

To locate the help file, you should select Start»All Programs»National Instruments»NI-DAQ»NI-DAQmx Help, and search for 'quantization error'.

I hope this helps, just let me know if you'd like anything clarified or if you have any other questions on the matter.

Regards