Last night (7-8 Feb) I was watching a recording. When it finished at
about 2 am I switched to Freeview to check the news on BBC1 via
teletext. BBC1 was not there. The TV said "No signal". I looked at some
other channels - similar. Freesat channels were fine. My initial thought
was that either there had been a total failure at the Divis transmitter
(Northern Ireland) or that the distribution amp in my loft had failed.

A bit more investigation showed that only some muxes were affected.
Because we are pre-DSO here I checked the analogue channels. BBC1 was
normal as was Ch5 (which is not from Divis), but BBC2, UTV, and Ch4 were
displaying snow. The 4 analogue channels from the Irish Republic were
normal.

I checked the signal strength and BER on a couple of the affected
Freeview muxes and found that they were normal even though the TV was
reporting "No signal".

Everything is back to normal this morning.

--
Peter Duncanson
(in uk.tech.digital-tv)

On 08/02/2012 13:03, Peter Duncanson wrote:
Last night (7-8 Feb) I was watching a recording. When it finished at
about 2 am I switched to Freeview to check the news on BBC1 via
teletext. BBC1 was not there. The TV said "No signal". I looked at some
other channels - similar. Freesat channels were fine. My initial thought
was that either there had been a total failure at the Divis transmitter
(Northern Ireland) or that the distribution amp in my loft had failed.

A bit more investigation showed that only some muxes were affected.
Because we are pre-DSO here I checked the analogue channels. BBC1 was
normal as was Ch5 (which is not from Divis), but BBC2, UTV, and Ch4 were
displaying snow. The 4 analogue channels from the Irish Republic were
normal.

I checked the signal strength and BER on a couple of the affected
Freeview muxes and found that they were normal even though the TV was
reporting "No signal".

Everything is back to normal this morning.

Yes, I see it was off (as far as the BBC were concerned) for 5 hours
from 00:35 to 05:25.

Probably a test of the post DSO muxes, they shut down the analogue
channels, and DTT muxes that will be replaced after DSO, and transmit
blank DVB-T and T2 carriers. A receiver won't find any services, because
the test muxes are kept deliberately empty but some will register signal
strength on their bar graphs.

Arqiva normally run these tests 6 to 9 months before DSO, to check the
new aerials and feeders etc.

BBC 1 would have been unaffected because it uses Ch 31, an allocation
not being used post DSO, and of course C5 is at Black Mountain


--
Mark
Please replace invalid and invalid with gmx and net to reply.

www.paras.org.uk

On Wed, 08 Feb 2012 13:42:40 +0000, Mark Carver
wrote:

On 08/02/2012 13:03, Peter Duncanson wrote:
Last night (7-8 Feb) I was watching a recording. When it finished at
about 2 am I switched to Freeview to check the news on BBC1 via
teletext. BBC1 was not there. The TV said "No signal". I looked at some
other channels - similar. Freesat channels were fine. My initial thought
was that either there had been a total failure at the Divis transmitter
(Northern Ireland) or that the distribution amp in my loft had failed.

A bit more investigation showed that only some muxes were affected.
Because we are pre-DSO here I checked the analogue channels. BBC1 was
normal as was Ch5 (which is not from Divis), but BBC2, UTV, and Ch4 were
displaying snow. The 4 analogue channels from the Irish Republic were
normal.

I checked the signal strength and BER on a couple of the affected
Freeview muxes and found that they were normal even though the TV was
reporting "No signal".

Everything is back to normal this morning.

Yes, I see it was off (as far as the BBC were concerned) for 5 hours
from 00:35 to 05:25.

Probably a test of the post DSO muxes, they shut down the analogue
channels, and DTT muxes that will be replaced after DSO, and transmit
blank DVB-T and T2 carriers. A receiver won't find any services, because
the test muxes are kept deliberately empty but some will register signal
strength on their bar graphs.

Arqiva normally run these tests 6 to 9 months before DSO, to check the
new aerials and feeders etc.

Thank you. I wondered whether it might be something like that. That must
mean that the new mast, aerials, etc, have been completed. DSO here will
be in October.

BBC 1 would have been unaffected because it uses Ch 31, an allocation
not being used post DSO, and of course C5 is at Black Mountain

Sky News and the other services on the Ch 48 mux were normal. Ch48 will
not be used post DSO.

As I said, I noticed this in the middle of the night. Once I'd seen that
it was not a failure inside my house I went to sleep without
investigating further.

--
Peter Duncanson
(in uk.tech.digital-tv)

On 08/02/2012 14:06, Peter Duncanson wrote:

As I said, I noticed this in the middle of the night. Once I'd seen that
it was not a failure inside my house I went to sleep without
investigating further.

Happening again tonight Peter:-

http://www.digitaluk.co.uk/how_do_i_...ineering_works



--
Mark
Please replace invalid and invalid with gmx and net to reply.

www.paras.org.uk

On Wed, 08 Feb 2012 14:27:50 +0000, Mark Carver
wrote:

On 08/02/2012 14:06, Peter Duncanson wrote:

As I said, I noticed this in the middle of the night. Once I'd seen that
it was not a failure inside my house I went to sleep without
investigating further.

Happening again tonight Peter:-

http://www.digitaluk.co.uk/how_do_i_...ineering_works

So it is. Thanks.


--
Peter Duncanson
(in uk.tech.digital-tv)