Complex Baseband
- From: "morpheus" <saurster@xxxxxxxxx>
- Date: 29 Mar 2007 17:09:24 -0700
Howdy,
For FM/AM demod, you require a complex baseband. I am downconverting
the IF from 1MHz to baseband by multiplying the input stream (12 bits)
from the ADC with Sin and Cosine outputs of a DDS and therefore,
generating I, Q
I am using standard 18x18 signed multipliers in Xilinx to do the
mixing. Is this right or should I use a complex multiplier?
The reason why I am asking this question is because, I had implemented
the whole datapath (Downconversion, Rate decimation, Compensating FIR)
and verified it on the bench and then implemented CORDIC for getting
FM, which never worked.
So instead I tried to do AM demod by not using CORDIC but (Sq(I) +
Sq(Q)) using standard 18x18 signed multipliers and still no AM demod
which is supposed to be simple.
Then I took the CIC and CFIR filters out and tried to do demod
straight after the mixing, still nothing.
So I'm kinda stuck here, any help will be appreciated
Thanks
-M
p.s. I don't have access to Matlab and System generator, but I'm
buying them next week. I figured, doing digital radio design without
modeling tools is like digging your own grave!!!
.
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