Create Timestamps on Photon counts

[sbart]

Hallo,

I get TTL Signals from a Photondetector and want to record their arrival times with about microsecond resolution (I have a PCI 6713 Card with 2 counters and use Measurement Studio in VC++). The signals arrive with a rate of about 10kHz (non periodically). A pulse is 25ns long.
My Idea was to input a 1MHz external source to the SOURCE of the counter and send the TTL from the Photondetector to the GATE, but the GATE  doesn't see the Photondetector-pulses (25ns is probably too short; the SOURCE however can see -- i.e. count -- them!).

Can you propose a solution? I have not found a (Measurement Studio) solution in the forum to my problem.

Thanks a lot

[Andre_Saller]

Accoriding to the specification (page A-6) of the board, the minimum pulse duration for both the source and the gate is 10 ns, so your puls eshould work both as a source and a gate pulse.

Maybe your counter is not configured correectly. If you are using a longer pulse (artifically generated for example) as the gate-pulse, does it work then? If yes it may be indeed a problem with your pulse, if not, the counter is not set up correctly.

You can have a look at this example:

http://zone.ni.com/devzone/cda/epd/p/id/1348

It is a CVI example, but as CVI uses ANSI C, the DAQ API calls are simillar in VC++

[sbart]

Yes, indeed it works with pulses of duration >1.5 ms (milliseconds!) on the gate.

[Andre_Saller]

Hmm. Two stars... is this the way you appreciate it, when someone tries to help you?

Anyway...

Have you tried it with the example I linked to?

This example uses the 20 MHz internal clock at the source. The minimal possible Pulselength at the Gate may be dependent on the pulses at the source. It would also help, if you could post the code your are using to programm your counter...

[sbart]

Sorry Andre, I was too stupid and mixed up the meaning of the numbers (in Germany it's the other way round at school..), I wanted to give a good evaluation!
Thanks for the fast and competent answers again!

I will post the part of my code soon. As I mentioned, on the source a pulse of even < 10ns is okay. Nevertheless I do the tests with about 1ms pulses on the source.