[mythtv-users] announce: script for locating QAM channels

[Brian Wood]

On Mar 4, 2006, at 9:47 PM, Peter Watkins wrote:

> All,
>
> I've been transitioning from an all-Hauppauge PVR-x50 0.18.1 system  
> to a
> 0.19 system with an HD3000 card that I hoped to use for QAM HDTV.
>
> The wiki page about adding QAM channels at
> http://www.mythtv.org/wiki/index.php/ 
> Adding_QAM_Channels_For_HDTV_Tuner_Cards
> has been very helpful, but the azap/mplayer steps seemed like a  
> bunch of
> work. To make things easier, I've cobbled together a script to  
> drive all
> the tasks involved in finding channels, testing them, and creating  
> a new
> channels.conf file.
>
> I've personally bailed on QAM for my setup b/c my QAM reception is  
> poor
> (though OTA/ATSC is pretty good). But I thought I'd put the script out
> for others' use. Comments are welcome.
>
Interesting, and I'll give it a try.

You say you have "signal strength" problems. "Unwatchably choppy"  
might describe what I have seen when using the azap/mplayer method on  
the 288 streams that atscscan found on my system.

But the BER shows zero on all of these channels, so I don't think it  
is a signal strength problem.

What did your system show for BER ?? I wonder if you are having the  
same problem I am. If I just run azap it shows "FE has lock" on every  
line, but when I run mplayer to try and watch a stream I then see  
many lines without the lock message, although a lot of them have it  
also.

Why would watching the stream affect the lock (if it really is). I  
get a lot of breakup when using -nosound, and it gets even worse if I  
try and use sound as well. I also get "too many packets in the   
buffer" messages from mplayer.

So I've had no real luck with QAM, with sumptoms similar to yours,  
but I really don't think it is a signal strength problem.

I have only one OTA atsc signal here, so if I can't get QAM signals I  
have a pretty expensive off-air demod, especially since my TV has a  
built-in atsc tuner.

But I'll play with your script and see where it leads me, thanks.