On Fri, Jun 10, 2011 at 3:12 PM, open bts <obts94...@hotmail.com> wrote:
> I'm looking to decode NTSC with my gnuradio. I found this > http://www.danielgarcia.info/thesis/ online where someone used > an older USRP and gnuradio version to decode NTSC and PAL. > I was able to mangle his script a bit to run with newer gnuradio > and UHD. (I hard-coded in some of the parameters for quick > testing, it needs some polish once completed). > However I still just get a black screen, so we're not > all the way there yet. > > Anyone around familiar with this code? The original code seemed > to have a sample rate of around 1Ms/sec (ie. adc rate 64M decimated > 64 times, if I read the code correctly). Is this enough for a tv signal? > It looks like an NTSC channel is around 6M wide (with color and > sound), right? > I've not played with this code, no, but 1 MHz bandwidth doesn't sound like it'll work. You can see the spectrum mask here: http://en.wikipedia.org/wiki/NTSC 1 MHz doesn't get you a whole lot of information in NTSC. You really need the entire 6 MHz. > I'm going to try to get a stronger signal to test with and play with > it some more, but if anyone is interested in helping, I'd welcome > the assistance. > Where are you getting NTSC transmissions now, anyway? Only low power TV is left in the US to transmit on NTSC, and I think most of them have moved away from it, too. I'm sure there's still signals out there, I'm just wondering where and what services would still be using it. I also don't know the state of NTSC outside of the US, but it was fairly limited to being with. Tom
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