fast speed TTL signal sampling

[gufwang]

Hi,

I am a beginner of Labview. Currently we are facing a new project that i believe fast data acquisition is the key point. If someone could give some guidance I would be greatly appreciated.


Board: AT-MIO-16E1
Signals: A series of TTL signals generated by an avalanche photodiode, 30 nanoseconds in width, the frequency of the occurence of signals could be as high as 10MHz.
Objective: Counting the number of TTL signals during a certain period of time, (form microseconds to milliseconds) store it somewhere, and repeat the counting and storing precedure for lots of cycles as many as the hardware allows.


Questions:
1. Is this a project for the board and Labview software?
2. As we imaging, there will be some deadtime tween th
e periods that the signals are being counted. Could we minimize the deadtime to a insignifcant value? (like 5% of the counting time?)
3. If it could be done by Labview, is there any additioal hardware we need to purchase? E.g. a board that provides gating signals.
4. Is there any exsisting examples we can copy?


Thank you,


Gufeng

[Labviewguru]

Being a long time user of the E1 boards myself, I would say that you MAY be able to do this. As I don't have the specs handy right now, I can suggest a means by which to come up with the solution for yourself:

Check the specs of the board. You are looking for the specs for the DAQ STC timer portion, as you want to do counting operations, not data acquisition. I don't remember if the DAQ STC on the E1 can handle 10MHz. If it doesn't, stop there, and get your NI Catalog and look for one of the newer boards with the advanced timing chips, I believe these can handle it. If the E1 can handle it, go on from there. Create a timing diagram for yourself, to get a visual picture of what you need. Then determine what gating and triggering you need. There are numerous
examples in the sample programs database in LabVIEW for counting. These should point you in the right direction.

Good luck

[markwysong]

I believe that the spec on the E-series board with the DAQ-STC is that you can toggle the counter at 20 MHz max, so it should be able to count your 10 MHz signal.

Mark

[June]

Sounds like you either need to perform buffered event counting or just simple event counting using the counter/timer on the E1 device. Regardless, there are examples under the example/daq/counters folder for these types of operation. NI-660x counter/timer devices are also an option. The 6602 and 6608 have eight 32bit counters and a 80MHz timebase, which means that you can count up to 80MHz (even higher if you programmatically enable the onboard prescaler). The 660x devices also supports advance features such as filtering, start trigger, etc. You can learn more about those counter/timer devices by downloading the 660x User manual.