Designing a data acquisition system

[jmarkwolf]

I am designing a data acquisition system for a very specific application. My signal sources will have a 2.5V DC offset and I was planning to use a mono-polar A to D.

It may become desirable to perform FFT's on the captured data, which requires no DC offset.

Is it advisable to null the signal sources to zero volts in hardware and make appropriate changes to my power supply and A to D, or is it just as effective to do it in software and keep the hardware simpler?

Also, how can you test the end-to-end phase error introduced by the hardware?

All suggestions gratefully received.

 

[kender]

IAlso, how can you test the end-to-end phase error introduced by the hardware?

If the carrier is available in your very specific application, you can feed it into the DAQ card and then the phase error between the signal and the carrier should become visible.

 

[jmarkwolf]

You mean, just watch the input vs the output on a 2-channel scope?

This won't distinguish lead/lag phase error.