Frequency measurement with pci6229

Hello
I’m trying to measure a frequency with my PCI 6229 device. This frequency can be between 1 and 200 Hz, so I use the one counter method. The problem with the signal is that there is a lot of jitter on it. So my device measures the frequency of the jitter and not the frequency of the square wave. What can I do to measure the signal right?
Another problem is the signal connection. I have connected the signal to the gate of the counter and the GND of my signal to the source. Is this the right way?
Thanks in advance!!
Attachments:
signal.JPG ‏31 KB

Hello Markske,
You will need to add a low pass filter on the signal that you are trying to measure to make sure that there is no high frequency noise that can get by.
Concerning the connection of your signal, it is only necessary to connect the signal you're interested in to the gate of the counter. The source would only be necessary in case you want to do the measurement with an external clock signal. If you choose to take an internal clock, the source can stay unconnected.
Using counters to measure frequency however is only possible with TTL-compatible signals (see link below). The screenshot that you added does not show a TTL-compatible signal so I presume this is due to some type of scaling that you added?
http://digital.ni.com/public.nsf/websearch/ACB4BD7550C4374C86256BFB0067A4BD?OpenDocument
Regards,
WouterVH
National Instruments

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