I am attempting to playback a CW tone using the PXI-5673 arrangement. For this example: 1.025GHz CW, centered
at 1GHz, arbitrary IQ rate, arbitrary bandwidth. I'm currently using the
unmodified ArbitraryWaveformStream.2010 example in Measurement Studio's
DOTNET-4.0 RFSG to stream a recorded CW tone.
What I have been observing is that the 1.025GHz tone comes through clear and
with no aliasing only when the pre-filter gain of the ni-5450 Vector I/Q Generator is set to a value less than or
equal to -50dB. Any higher than this and there appears to be aliasing which
results in a "raised" noise floor across the bandwidth of the streaming signal,
appearing as a plateau surrounding 1GHz by +/- 0.5*BW. How can I determine,
for general use and a variety of recorded signals, what the pre-filter gain
level should be to prevent aliasing?
