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Do we need a preamplifier for NI PXI-5124?

I need to buy high speed ADCs for my lidar system. But I not clear whether I need a preamplifier between PMT and NI PXI-5124.
Thanks for information.
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Hey LD,
Refer to page 3 of the specifications for the PXI-5124 to see the different voltage level settings. http://www.ni.com/pdf/manuals/371135a.pdf
I do not know anything about a lidar system, so I do not know how small (or big) the signal is going to be. If you look at the specs, though, you can see that you have the choice of having an input voltage from 200mV (pk-pk) to 10V (pk-pk). What this does is put a gain on the input signal so that the full range of the ADC is used (12-bits for 5124). So if you put in a signal that is only 200mV pk-pk (and set it up in software for a 200mV signal) a gain is incurred that will "boost" the signal to the full range of the ADC (10V pk-pk in this case). All 12 bits will now be used to measure the signal with greater precision. (NOTE: all this is done internally)
However, if your signal is much smaller than 200mV pk-pk, you may consider preamplification.

Good luck, LD, and thank you for choosing National Instruments!

Sincerely,
Gavin Goodrich
Applications Engineer
National Instruments
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