After weeks of pulling my hair out, I’ve finally sorted my channel scanning problem and got BBC HD! The breakthrough was that it all worked in Windows, which narrowed it down to software on the Linux side. I’d tried scans with 3 different applications, which meant that it was either the firmware or the Linux DVB drivers causing the issue.
Because I’m on Intrepid with a 2.6.27 kernel (it all works on 2.6.28) I’d previously compiled the latest DVB drivers as described here:
So, I went through the process again with the latest snapshot of the v4l-dvb tree and… all transponders scan OK, including transponder 50 which has BBC HD. Phew!
Someone must have broken the v4l-dvb driver at the point I downloaded and compiled it the first time. A lot of effort wasted due to a bit of bad luck