Effective filtering must occur between antenna and receiver. All the problems that a saturated preamp and ADC cause can’t be repaired by software. Never.

Ralph.

From: osmocom-sdr-bounces@lists.osmocom.org [mailto:osmocom-sdr-bounces@lists.osmocom.org] On Behalf Of David Jacobowitz
Sent: Tuesday, October 22, 2013 10:45 AM
To: Sylvain Munaut
Cc: osmocom-sdr@lists.osmocom.org
Subject: Re: odd results working at 250ksp/s

Thank you. You and another forum member have helped me understand the situation. I am beginning to see the attraction of SDR platforms that integrate an FPGA immediately after the ADC. You can have wide analog filtering going to an ADC running fast, and then apply digital filters in the FPGA before downsampling to a lower rate for consumption by what-have-you.

I can accomplish the same completely in software; I'll set the sample rate high, then filter and decimate, probably in a few stages to keep the filters reasonable. I tried it this evening with some raw IQ recordings I made this afternoon and it works pretty well -- on a modern PC.

Regards,

Dave J