01-11-2011 01:52 PM
I am using one channel of a NI-9264 to drive a laser modulation voltage. Given this DAC will swing +-10 volts with 16 bits of precision, I should have a resolution of about 300 microvolts. I can see this resolution on a scope, but I also see about +- 2 millivolts of noise.
I am using a BNC ended coax cable to connect the 9264 to the scope, but there is a short section of wire coming out of the 9264 terminal block to a female BNC. Does anyone have a suggestion how best to determine if this +- 2 millivolts of noise is real or a product of me measuring such low voltages.
Thanks,
Steve
01-12-2011 04:33 PM
Hello sbailey64,
There are several sources of noise e.g the environment and also the scope itself. To eliminate possible causes, I would recommend testing a different signal source other than the DAC e.g a function generator? If noise is still observed then the issue may be stemming from noise introduced by the scope. Additionally, you can also verify the DAC signal using a hand held DMM. If these results are consistent with your initial observations then there could be a possible issue with the DAC. However, before you narrow down to a hard conclusion, dont forget to investigate the wiring (check if tightly secured/try a different cable) and the application environment e.g lights, electronic devices etc.
Best regards,
Ali M
Applications Engineer
National Instruments