Hi,
I have a question about the resolution of the NI-9263 Analog Output module.
The specs say it's 16-bit resolution, and that it has a 20V range (-/+ 10V). I wish to use the NI-9263 to replay a 16-bit recording of a waveform, but I need the output to be between 0V and 1.2V.
I have 2 choices:
1) Use LabVIEW to scale my waveform to be between 0V and 1.2V, before sending it to the NI-9263, or
2) Send my waveform to the NI-9263 (taking advantage of the full 20V range), and then attenuate it and shift the DC level using op-amp based circuits.
I think that option (2) is better, but I want to verify my reasoning in this forum.
If the resolution of the NI-9263 is 16 bits, this corresponds to 65,536 different voltage levels that can be represented. I'm assuming that this is over the full range of the part, so the device can generate voltage levels separated by 300 uV (= 20/65536). Now, if I was to squeeze my waveform into a 0-1.2V range, i.e. option (1), I'm assuming that this corresponds to only 4000 (=1.2/0.0003 approx.) of these voltage levels. This is roughly 12 bits, which means that I would be essentially losing 4 bits of information from my waveform.
Using option (2), I would get an analog output voltage with 16-bit resolution, and no information would be lost from my waveform. The disadvantage is that some external circuitry is required for the attenuation and the level shift.
Just wondering if the above reasoning is correct. On the other hand, it may be the case that the device adapts when you specify the maximum and minimum voltage levels (via the "DAQmx Create Channel (AO-Voltage-Basic).vi"), so that the voltage levels are separated by less than 300uV (in my case, I would require ~18uV separation to achieve 16-bit resolution over the 1.2V range).
Best regards,
Robert McEvoy
