bandpass filter

[gdengineer]

I would like to measure the amplitude of a given frequency in an analog input signal.  The frequency is 10 kHz or less.  What is the easiest and most efficient way to do this?  I imagine that one way is to use a high-speed digitizer and implement a digital bandpass filter.  Can I implement a such a digital filter continuously?  What CPU load could I expect?  Could I use an FPGA instead of the CPU?  Another way to accomplish the task is to use an analog filter.  Does NI sell any such analog filters? 

[Brooks_C]

Hello gdengineer,

First off, I want to welcome you to the National Instruments forums!

There are a very large range of solutions available for filtering signals.  Essentially you need an analog input channel that samples at least 2 times as fast as the frequency of interest if you're interested in frequency data.  If you need amplitude data you should probably shoot for 10 times the frequency of interest.  It is possible to implement digital filters continuously even at very high sample rates.

Unless you're implementing a control loop where you require a very fast reaction time I wouldn't think a hardware filter would be necessary, however if you are doing this there are hardware options available (including FPGAs).  With regards to the CPU load, there are so many factors that it is nearly impossible to predict the CPU usage without benchmarking it on the machine you'll be using.

If you'd like to provide a more detailed description of what you're looking to do it would be much easier to point you in a specific direction.  If you'd prefer you could also talk with a sales representative directly (www.ni.com/contact).  They are familiar with the full range of National Instruments products, and know how to help you find what you need.

I hope this helps, and have a great week!