All posts by mst
Below are all of mst's postings, with the most recent are at the bottom of the page.
M
Diary of changes to capacity of ArqB, ArqA and SDN multiplexes Wednesday 2 November 2011 9:11AM
St. Albans
Briantist: take Oxford for example - the com muxes are currently -9dB relative to the PSBs, COM power up due next April to take them to -3dB.
Due to mode change on ArqA and B the effective difference for same picture quality is raised as per your table above.
OK Its only 3Mb/s null packets - at the moment, but I suggest this change has not been well communicated - not needed until there are actually new channels.
Clearly there's techno/commercial issues at play - but anyone who can receive the COM multiplexes could clearly benefit from same mode change on the PSB muxes - higher bitrate better quality on existing channels please!
Are you suggesting the pre-DSO BBC Mux B is also going to carry a couple of extra commercial channels? It already carries Sky Sports 1 and 2 so there is precedent, but most folk can't see them!
| link to this comment |
M
Diary of changes to capacity of ArqB, ArqA and SDN multiplexes Friday 4 November 2011 8:50AM
St. Albans
Briantist:I understand the link between bitrate and quality when reception is fine, but there will be a 'fringe area' where the digital signal quality is close to the cliff-edge between watchable and not (Analogue TV had more graceful degradation). The power difference between PSB and COM makes it clear that some will only be able to get PSB channels, and there will be a 'fringe' area where COM is marginal. The mode change just moves this fringe in towards the TX a bit.
| link to this comment |
According to digital UK postode checker the Oxford TX has already switched the SDN mux to FEC 3/4
Also gives the final channel change for this mux from C62 to C50 in 2013
| link to this comment |
According to recently updated digital uk postcode checker
SDN mux C62 now apparently using the higher bandwith, slightly less robust FEC 3/4. And C62 will change to C50 in 2013
| link to this comment |
Page 2
Tuesday 1 November 2011 9:00AM
As discussed in here
Freeview on Oxford TV transmitter | ukfree.tv - independent free digital TV advice
Oxford TX ArqA and B were in this mode at the end of September, so I would guess they slipped it in at DSO2 on the 28th - despite the fact that the com multiplexes are only at 1/4 of their intended strength and 1/8 of the PSB there was still an improvement compared to pre-DSO.
Users still in marginal receptions areas will be rightly annoyed by this - their reception is currently impaired due to an engineering test sending out 4MB/s unused null packets right now!
Where is the official notification of this test - and what/when is the intended use of the extra capacity? Surely unlikely to be used before Crystal Palace goes through DSO2?