Digital Transition

So it turns out we're going fully-digital in March (the Midhurst transmitter). This, apparently, explains why we've got absolutely shonky Freeview reception at the moment. Channels disappearing, then re-appearing, appallingly broken-up pictures and sound etc. Ahh, digital. Degrades so much more finally than Analogue...


My parents went this time last year. My dearly sainted mother described the process as "the picture was horrible or unwatchable for a couple of months. Then your father retuned and it got better".  Well, we've got the same.

Since about Jan 10th , the BBC multiplex (Mux-1) has been fine. But availability of everything else has been spotty: poor to nonexistent during the day, occasionally fine in the evening, rarely good late at night.

Nerd that I am, I've managed to track this behaviour on my Myth box using "tzap". 

Here's a working channel:

 tzap -a 0 -f 0 -d 0 -c scan_localfreq_channels.conf 'BBC ONE'
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
reading channels from file 'scan_localfreq_channels.conf'
tuning to 754000000 Hz
video pid 0x0258, audio pid 0x0259
status 1e | signal 0000 | snr 0000 | ber 001fffff | unc 0000303d | FE_HAS_LOCK
status 1e | signal 0000 | snr 0000 | ber 000000d0 | unc 00000000 | FE_HAS_LOCK
status 1e | signal 0000 | snr 0000 | ber 00000080 | unc 00000000 | FE_HAS_LOCK
status 1e | signal 0000 | snr 0000 | ber 000001c0 | unc 00000000 | FE_HAS_LOCK

And here's one that's probably not right now:

tzap -a 0 -f 0 -d 0 -c scan_localfreq_channels.conf 'Channel 4'
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
reading channels from file 'scan_localfreq_channels.conf'
tuning to 826166670 Hz
video pid 0x0230, audio pid 0x0231
status 1a | signal 0000 | snr 0000 | ber 001fffff | unc 00000000 | FE_HAS_LOCK
status 1a | signal 0000 | snr 0000 | ber 001fffff | unc 00000000 | FE_HAS_LOCK
status 1a | signal 0000 | snr 0000 | ber 001fffff | unc 00000015 | FE_HAS_LOCK
status 1a | signal 0000 | snr 0000 | ber 001fffff | unc 00000000 | FE_HAS_LOCK
status 1a | signal 0000 | snr 0000 | ber 001fffff | unc 00000000 | FE_HAS_LOCK

Spot the differences? Status = 1e on BBC1, 1a on Channel 4. Constant high Bit Error Rate on C4, variable but much lower on BBC1.

Later in the evening I might get to see actual values for "signal" and "snr" (Signal-to-Noise) on both channels, which is an indication all is working well at the minute.

Now the experience of my parents above means basically that I should just sit back, wait until the switchover is complete in mid-March, and then start worrying if I can't get it to work again. And I'm mostly resigned to this. But I have a nagging feeling I'm actually looking at a local problem, not a switchover artefact: Up in the roof we've got a signal booster, tucked away where we can't see it. And I'm wondering whether it's gone "phut" recently....