Re: [Discuss-gnuradio] USRP Custom Filter Taps

[Matt Ettus]

Daniel Garcia wrote:
> I am working on an NTSC receiver using the USRP/TVRX board. I am tunning the 
> board to 63.25 MHz with decimation set to 10; this gives me 6.4 MHz of 
> bandwidth. The NTSC channel is 6 MHz wide so with these settings I get some 
> interference from the adjacent channels. 
>
> Is there a way to set the filter taps used by the USRP so that I could make a 
> filter to remove the frequency infomation at the extreme right and left of 
> the sampled data? I can use an FIR filter in the PYTHON runtime but it uses 
> lots of CPU power.
>
>   
Yes, you can change the filter taps in the FPGA.  See the halfband (HB)
verilog code.
> I read on a previous thread that it is possible to invert the spectrum of the 
> sampled signal so that the tuned frequency would be the FM carrier. The end 
> result being a stream from the USRP where 0 Hz is the center frequency of the 
> audio carrier the the video carrier is at 4.5 MHz. Is this possible? The 
> advantage here is that the baseband audio does not need to be shifted before 
> fm demodulation; also the video carrier does not need to be shifted before 
> demodulation (AM). 
>   

Not sure what you're looking for here.

Matt