jewaniuk

We are looking at purchasing a Digilent DAQ for the following application, but are confused as to the specifications required and thus the model we should purchase. We have a single-photon detector that is an avalanche photodiode (APD). When this detector detects a photon (i.e. an event), it produces and outputs a TTL pulse that is typically 20 ns in width with < 2 ns rise and fall times. It is not important for us to resolve the time that the TTL pulse arrives at the counter on the DAQ, however, it is important that we do not miss counts. I have noticed that the USB-1208HS series features counters that have a maximum input frequency of 20 MHz. My understanding is that this corresponds to bin width of 50 ns. Please correct me if I am misguided, but does this mean that this module could potentially record multiple TTL pulses in the same bin, leading to a count of 1 that should be 2? If so, are there any other products that would be more suitable? For some additional information, here are some more desirable specifications for the DAQ we are hoping to purchase: Near 1 MHz sampling rate Analog I/O & Digital I/O with at least two dedicated counters Support for Python control Connected to computer via USB Thanks!