odd results working at 250ksp/s

Ralph A. Schmid, dk5ras ralph at schmid.xxx
Tue Oct 22 08:44:13 UTC 2013


> The filters you'd need wouldn't be in the R820T anyway (it has filters but not
> that narrow).
> IIRC, the rtl2832 always sample at a fixed high frequency but it has an internal
> downconverter + FIR filter inside to convert the sample rate down. But that
> FIR probably can't handle such a big reduction ...

Still we must not forget that we're talking about some piece of silicon with nm 
structures, and therefrom no extraordinarily sharp filtering can be expected. 
When analog meets digital, it is important that the analog part protects the 
ADC from being overwhelmed by strong signals that are not in the scope of 
interest.

All those silicon-only broadband receiver concepts drastically fail when being 
directly connected to a real good antenna in urban vicinity. They are good for 
a rubber duck style antenna sitting on your table, but that's it. 

There's a reason for all the solid silver and brass stuff in real world receivers :)

> Cheers,
> 
>    Sylvain

Ralph.





More information about the osmocom-sdr mailing list