Dynamic Signal Acquisition

[Alan_[DE]]

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.

-alan

[ecborgoyn]

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).

[BrettBymaster]

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.

[ecborgoyn]

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....