Digital downconversion

I would like to get pointers to digital downconversion topics. Or, practical projects (maybe HAM ... )experimenting with digital downconversion receivers, preferably using FPGAs.

Thanks, Dan

Hi,
I hope you are not looking for DIRECT digital down conversion.

I had used digital downconversion for a GPS receiver. It is fairly easy. you follow in digital all the process of analog. However you need to be careful about sampling and quantization levels.
B R
Madhukar

Yes, im looking for direct digital downconversion. What im interested in more exactly is a pointer to a paper ilustrating the calculus of ideal sampling rates,
issues of undersampling, and so on. I found pointers on how to implement it in FPGA, but the paper does not mention ADC requirments pahse for sampling.