Hi,
I am currently trying to generate passband noise using a PXI-5441 100 MS/s AWG OSP and see the resultant IQ graph using a PXI 5600 Downcoverter and a PXI-5620 64 MS/s Digitizer.
Theoretically, I'm modeling my noise after a narrowband noise nI(t)*cos(2*pi*fc*t) - nQ(t) *sin(2*pi*fc*t), where nI and nQ are my in-phase and quadrature components and fc is my carrier frequency. I'm confused about whether I should use a complex waveform to modulate my waveform on my 15MHz carrier, since the signal I'm trying to model after is real. But I also know that if I don't put it as a complex waveform, I wouldn't be able to get the correct IQ graph. Is that a correct assumption?
I'm using a Gaussian White Noise to generate my in-phase and quadrature noise components and I'm using NI-FGEN subVI's to sample my noise and generate it on a carrier frequency (PB v2.vi). What I get on my IQ graph (IQ.vi) is some noise that travels around in a circle when I expect that there should be a circular fuzz centered at zero. Any suggestions?
I've attached all the appropriate VIs if you'd like to look at it.
Thanks!
Sammy
