12-21-2011 11:30 AM
I've only skimmed this thread so perhaps this has been covered, but wanted to make sure to point out that DSA products have a dedicated ADC per channel, thus support true simultaneous sampling. Most DAQ products have a single ADC and mux the input channels, which is obviously not simultaneous sampling. This may or may not be important to your application.
02-06-2012 01:18 PM
Are these glitches between EVERY sample? Or perhaps at tbe beginning and end of every output 'task'? I don't see how they can occur between samples, unless they can be easily filtered out.... I need to create audio streams, and perhaps the glitches are not apparant in the band of interest (they only have very high frequency content.. I'm sure the DSA type H/W can prodiuce audio stream, but I was looking for a lower resolution (accompanied by a lower price).
02-06-2012 01:26 PM
The glitches occur at the binary transitions -- i.e. the transition from 01111 to 10000. So you'll see one big glitch for every wavelength. You might be able to recenter the waveform with a DC bias such that you never use the MSB bit of the DAC. That might help. You can also filter, but I'm not sure you can maintain hi-fidelity with that method.
02-06-2012 03:03 PM
Thanks. Duh... I should have thought about the 'resistor ladder' type of DAC and the bit transition glitches....
The devices that I would be driving with the analog output are inherantly band-limited and have anti-aliasing filters. This should help. But the glitch will be puting lots of energy into any kind of filter. I need to think about this one....