The best way of eliminating any false pules while aquiring on counters in Daq card

[GNS]

Hi,
usually i monitor the RPM of any moving object and for that i use inductive proximity sensors for the same. These proximity sensors are supposed to give out a pulse at every rotation. for monitoring and all i count the no. of pulses at eihter of the counters in my DAQ card. most often what happens is i use to have false pulses in between also and that results erratic readings. So i wanna know if this problem is solved by software filtering and all or there is some hardware solution. how can i be sure that the conter is always counting the right no. of pulses.
Please have a look into the problem and give ur valuable solutions.
Regards
GNS

[Bill B]

Hello,

It is not possible to due filtering in software when using counters. You would need to write an algorithm that would decide whether a pulse was valid. This is simply not possible. What you need is either a low-pass filter circuit to remove any false edges or you need one of our counter/timer boards that have built-in filter clocks that can also reject false pulses. Here is a link to our 6602 board which would work very well for your application:

http://sine.ni.com/apps/we/nioc.vp?cid=1123〈=US

If you choose to implement a simple RC filter, you will simply need to choose R and C combinations that will reject the high frequencies, yet not attenuate your actual signal.

Regards,
Bill B
Applications Engineer
National Instruments