<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><br></div><div>Thanks all for your informative responses. My TV is a Panasonic and has always tuned itself perfectly wherever I've lived.</div><div><br></div><div>I appreciate you all taking the time to post this info, trouble is you've all assumed I have qualifications in broadcast technology. </div><div><br></div><div>For example:</div><div><br></div><div><blockquote type="cite"><span class="Apple-style-span" style="font-family: monospace; ">Select the transports that match your "good" transmitter and do a "Scan existing transports" instead of a full scan</span></blockquote><br></div><div>What are transports? How do I know which transports match my good transmitter? Where do I go to select the transports once I've found out? Why do I even need to know all this when Panasonic can make a TV that does it all for me?</div><div><br></div><div>I appreciate that mythtv is international and that what works here won't work anywhere else, but I still think it'd be worth giving it a go because over the years I've been using it I've come to feel a sense of terror whenever I think something might need reconfiguring :)</div><div><br></div><div>Mark</div><br><div><div>On 21 Oct 2012, at 10:32, Karl Dietz wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>On 21.10.2012 01:37, Jean-Yves Avenard wrote:<br><blockquote type="cite">Hi<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">On Sunday, 21 October 2012, Mark Greenwood wrote:<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"> In the UK, DVB signals include channel numbers, so by 'sensible' I<br></blockquote><blockquote type="cite"> mean 'following the channel order as defined in the signal'. Mythtv<br></blockquote><blockquote type="cite"> appears to ignore this. A rescan on my myth box takes 15 minutes,<br></blockquote><blockquote type="cite"> then I have at least 2 copies of each channel so I have to work out<br></blockquote><blockquote type="cite"> which one is the best for each channel then set a channel number and<br></blockquote><blockquote type="cite"> delete the others. But then because I've set my own channel numbers<br></blockquote><blockquote type="cite"> but myth invents new ones when I rescan (e.g. 4283 for BBC1..huh?) I<br></blockquote><blockquote type="cite"> get loads of duplicates as well. It's a nightmare. It also doesn't<br></blockquote><blockquote type="cite"> take account of the signal strengths of the channels it finds,<br></blockquote><blockquote type="cite"> whereas my TV will choose the best signal for each channel and<br></blockquote><blockquote type="cite"> discard any duplicates, hence I only get one BBC1 and it's on<br></blockquote><blockquote type="cite"> Channel 1, instead of 3 of them randomly distributed across the<br></blockquote><blockquote type="cite"> channels like I get with mythtv. (The first scan, I had BBC1 on<br></blockquote><blockquote type="cite"> channels 1, 46, and 4283. Where did it get those numbers from? The<br></blockquote><blockquote type="cite"> only one that gives a decent picture is the one on 4283 so it sho<br></blockquote><blockquote type="cite"> uld have chosen that one and thrown the other 2 away).<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Myth uses the channel as defined by the DVB stream. It may not be what<br></blockquote><blockquote type="cite">you're used to, but that's what the broadcast uses.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">In Oz, after a scan, channel 9 is on 9, Seven on 7, Ten on 10 etc..<br></blockquote><br>In the UK you'll get duplicates if you can receive multiple networks<br>(aka transmitters carrying the same channels). You'll get random<br>channels if you get the same transport (as identified via<br>original_network_id and transport_id) is received on multiple<br>frequencies. That's a known error that I've seen on german DVB-T.<br>Yes, the proper way is collecting them all and picking one of them by<br>default, maybe depending on bit error rate or signal strength (up to<br>the implementer)<br><br>The easiest work around is to not perform a full spectrum scan but<br>instead start on a known frequency of one of the networks/transmitter<br>sites and letting the scanner learn the related frequencies from the<br>network_information_table.<br>You should only get one copy of each channel that way.<br><br>I was sure that the channel scanner supports the logical_channel_number<br>transmitted in the network_information_table (1 for BBC1 in your<br>example) but I can't find any evidence in the code right now.<br>The 4283 is coming from the service_id that is used to refer to this<br>service in other DVB tables. I've no idea where the 46 is coming from.<br>(the logical_channel_number is what got shuffled around lately<br><a href="http://en.wikipedia.org/wiki/List_of_digital_terrestrial_television_channels_(UK)">http://en.wikipedia.org/wiki/List_of_digital_terrestrial_television_channels_(UK)</a> )<br><br>Once you have that scan done you can run <a href="http://www.mythtv.org/wiki/UK_Channel_Assignments">http://www.mythtv.org/wiki/UK_Channel_Assignments</a> to connect to the channel_ids from tv_grab_uk_rt<br><br>Regards,<br>Karl<br>_______________________________________________<br>mythtv-users mailing list<br><a href="mailto:mythtv-users@mythtv.org">mythtv-users@mythtv.org</a><br>http://www.mythtv.org/mailman/listinfo/mythtv-users<br></div></blockquote></div><br></body></html>