Monday, January 7, 2019

nyquist - Bandwidth with complex sampling


On the transmit side, I have a 20 MHz carrier frequency carrying a signal with bandwidth of 40 MHz (so 0 Hz to 40 MHz, center at 20 MHz).


On the receive side, I have a dual channel ADC with each channel sampling at 40 MS/s (channel 1 samples at 40 MS/s, channel 2 samples at 40 MS/s). The hardware is setup to input I and Q into the two channels.


Am I able to properly sample the received signal, without aliasing? I saw that this was discussed before ("Complex sampling" can break Nyquist?), and the answer seemed to be "BW = fs because you get the negative frequencies", and I'm not 100% sure if the "negative frequencies" thing is a caveat, or I can just do the math as if I am getting 80 MS/s (which I technically am), so I drummed up this numerical example.




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