PALM / NTCS Audio demodulation

GNU Radio
1

I am trying to modify the version of usrp_tv_rcv.py in the CVS in order
to
demodulate the audio component of the PAL-M signals. Has anybody have
success on doing that for NTSC jsut so I could compare both codes or has
naybody done it for PALM?

Thanks,

2

Augusto Pedroza wrote:

I am trying to modify the version of usrp_tv_rcv.py in the CVS in
order to demodulate the audio component of the PAL-M signals. Has
anybody have success on doing that for NTSC jsut so I could compare
both codes or has naybody done it for PALM?

If all you want is the audio, I would start with usrp_wfm_rcv.py. It
should work right off the bat. You can change the constants in there to
make it match the standard more closely.

Matt

3

I’ve built an application that intends to output both signals video and
audio, but I haven’t been able to test it because it requires a lot of
computer power.
i just added these lines:

self.u = usrp.source_c(decim_rate=options.decim,fpga_filename=
self.fpga_filename)
self.u_audio = copy.copy(self.u) – Creates a copy just so I can set
a
different frequency for the audio sink

the audio frequency gets the input frequency and adds 5.75M
and the video frequency adds 1.25 to the input.
PS. The input frequency should be the lowest frequency of the VSB
for example if VSB = 210 - 216, the input should be 210M

4

On Mon, Jul 10, 2006 at 03:42:12PM -0300, Augusto Pedroza wrote:

and the video frequency adds 1.25 to the input.
PS. The input frequency should be the lowest frequency of the VSB
for example if VSB = 210 - 216, the input should be 210M

I’m not sure what you’re trying to accomplish with copy.copy.
My suggestion is that you suck down the entire Video + Audio in one
stream from the USRP, and then split off the audio using an instance of
gr.freq_xlating_filter_ccf.

Eric