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Ptolomey Simulation Bandwidth Question

Question asked by dbengtson on Jun 10, 2006
I've build a ZIF receiver model in Ptolemy, and I'm trying to determine the impact of 1/f noise on the BER. After the downmixer stages in the receiver, I've added a summer and a NoiseFmask block. The output of the NoiseFmask and the output of the mixer feed into the RF summer, and the output of that goes into the demodulator.

The problem I'm having is that the output of the NoiseFmask block doesn't reach the 10 kHz low end frequency that I'm expecting to see. The Ptolemy simulation is from 13 MHz to 90 MHz, and the shaped noise only extends 13 MHz to 90 MHz.

I'm confused at this, Since I see that the output of the mixer extends from DC to 38 MHz, I was expecting that the output of the NoiseFMask would extend from 10 kHz to the 90 MHz simulation BW. What am I getting wrong here?