I am working on a long range nanopositioning system. The
positioning system has to provide 1 nm resolution over 10mm. Therefore,
requirement for the dynamic range is 10mm/1nm = 24 bits (approx).
We bought NI PXI4461 sometime back. It has 24 bit AO but it is supposed
to be used as dynamic signal analyser.We tried to use it in a closed
loop at very low frequency, but we were not able to achieve even 10 Hz
loop rate. We got help with engineers at NI but we couldn't find a
solution to the problem.Apparently, there is a lot of delay at the
output due to buffering.
However, we also have one NI PXI6281 which has a 16 bit AO. There is not problem of running this one even at 5KHz loop rate. I found this interesting article on NI's website which talks about increasing the resolution of a DAC using NI Hardware/software. (http://digital.ni.com/worldwide/bwcontent.nsf/web/all/280FFE517B815F58862572D7004EE028)
1)
Could we use something like hyperbit to get higher performance (in
terms of number of bits). We are ready to sacrifice on the bandwidth up
to 1 KHz.
2) Hyperbit may increase the number of bits, but what
about the electronic noise of the DAC? Does the effective resolution
still remains the same. Or there is an improvement in the effective
resolution also?
Please let me know what you think
Thanks a lot.
