Hello,
I have had similar experience like You with the same card (TT DVB C1500)
regarding QAM64. I discovered that there had been a successful fix for
this done for QAM128 by changing the sweeprate, see
http://www.linuxtv.org/pipermail/linux-dvb/2006-February/008439.html
So I made some test to find a working sweeprate for QAM64, see
http://www.linuxtv.org/pipermail/linux-dvb/2006-May/010141.html
You might have to the same trip for QAM256?
Look at line 419 in stv0297.c,
http://linuxtv.org/hg/v4l-dvb?f=e399629b4743;file=linux/drivers/media/dvb/frontends/stv0297.c;style=gitweb
Suggestion:
--- stv0297.c.orig 2007-04-12 19:18:48.000000000 +0200
+++ stv0297.c 2007-04-12 19:20:06.000000000 +0200
@@ -404,10 +404,13 @@
break;
case QAM_128:
- case QAM_256:
delay = 200;
sweeprate = 500;
break;
+ case QAM_256:
+ delay = 200;
+ sweeprate = YOUR_SWEEPRATE;
+ break;
default:
return -EINVAL;
best of luck
Per Dalén
Petri Helin wrote:
Hi,
I am not completely sure if this really is connected to the channel
using QAM256, but that's what I suspect. I use Technotrend's TT-C1500
budget card with appropriate common interface and Conax CAM. This
combination works flawlessly on every channel which uses QAM64 or
QAM128. Now the Finnish cable company, for which I am subscribed to,
started broadcasting Canal+ Film HD some three months ago. This has
worked otherwise quite well, but I get constant disturbances/artifacts
in the picture. I used to think that it was just because the bit rate
was five times the normal (17 Mbit/s compared to 3-4 Mbit/s).
But couple of days ago I noticed that this channel is actually the
only one I am receiving that uses QAM256. Searching the Internet
provided me with couple of forum threads/mailing list posts that
suggested that certain DVB-C cards might have problems in receiving
QAM256 modulated broadcast, but the hits were mainly on VDRportal and
in German and I might have lost something in the translation... In
addition to the picture getting garbled every now and then I can
notice the problem also from the high values of UNC (uncorrected
blocks) and BER (bit error rate). On Canal+ Film HD UNC is between 0
and 20 and BER is about 250. On all other channels UNC is 0 and BER
close to 0. STR ja SNR are the same on all channels, including Canal+
Film HD.
Now what I am asking is for any experiences using DVB-C cards to
receive QAM256 modulated broadcasts, no matter if HDTV or not.
-Petri
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