All posts by Charles Stuart
Below are all of Charles Stuart's postings, with the most recent are at the bottom of the page.
QPSK may allow for fewer channels but if the objective is meaningful local television, QPSK will be needed for these local channels to reach many significant population centres. My understanding is that an 8MHz PAL I TV channel can deliver three or four DVB-T channels using QPSK. As few areas would have the economic ability to support more than one or two local channels, I think that QPSK is the obvious choice. I guess that it depends where you put the priority and I'd definitely go for greater coverage with fewer channels.
I think that if two or three Digital Dividend channels were sacrificed to allow full local television coverage, that would be a good thing. That would still leave 12 or 13 channels to be sold off. Again, I guess it's about priorities and I'd like to see local television heading the list.
| link to this comment |
While I can see from the figures provided by Mike Dimmick that QPSK probably does limit the number of channels to two, it still seems the better option to me. I can't see many areas having the economic capability to sustain more than two local channels, London, Birmingham, Manchester, Newcastle and Glasgow being really the only possible exceptions.
However, there's been no discussion of the possibility of using 16QAM. How would that affect reception? Particularly in England, I think that 64QAM simply won't cover the population in significant areas sufficiently for a service to be economically viable. The problem with 64QAM is that the signals so often totally miss the major population centre being served by the PSB and COM services from the same transmitter.
Maybe, as many of these transmitters have a second frequency available, if 64QAM were to be adopted perhaps the second frequency could be allocated to new transmitter locations to increase the coverage of the service. As an example, the second frequency available to Crystal Palace could be assigned to a new transmitter near Junction 3 or 4 of the M25 to serve south-east London.
| link to this comment |
As a purely political statement, I think that British governments have neglected local broadcast media almost all the time since broadcasting started. I think that this is wrong. I think that some of the channels being given up for alternative use should be clawed back to provide a comprehensive local television system in every urban and suburban area of the country, covering rural areas as well as possible. I think that this should be done regardless of the relative financial cost/gain of alternative uses for these frequencies.
I think that local television is an important tool in contemporary democracy and that it also helps to preserve areas' sense of identity. Where all TV is regional or national, it seems to me that everywhere and everyone gets homogenized. Having lived in the US thirty years ago, I feel an understanding of how local broadcasters can contribute to local identity. US broadcast television is often criticized as bland and boring but its local stations can also be a focus for their communities.
While I don't suppose that posting on this site will influence anyone in a position of authority, one can at least try.
| link to this comment |
I'm quite surprised that so many people in Bedfordshire and Cambridgeshire are suffering reception issues. I'm in Kettering, Northants and my two TVs receive all multiplexes perfectly and the bedroom TV is fed from a set-top aerial. The Eye TV on my Mac has a harder time because the aerial has to "see" through two walls for its signal, but it still picks up the PSB multiplexes absolutely fine.
Out of curiosity, as ArqB is now on its final channel, 48, and now in 8K mode, when will it increase to its final power? (52.3992,-0.7201)
| link to this comment |
This is just a theoretical question because it interests me. I guess that eventually the five DVB-T munltiplexes will be converted to DVB-T2. When that happens, could they be reconfigured to create eight new multiplexes and a leftover frequency that could be used for other purposes?
Another idea I've had is that when the first of COM 7,8 or 9 opens, one of the existing multiplexes could be transferred to enable a truly local television service, along the lines of ITV when it first started but with local, rather than regional franchises and much more local content in each franchise area. (52.3992,-0.7201)
| link to this comment |
My idea was that if they convert from DVB-T to DVB-T2, I guess that they need to build new transmitters. If they're building new transmitters, why not reallocate the frequencies to the same, more efficient model that will be used for COM 7 & 8? If you can change five frequencies per multiplex to three per multiplex, why not do it to create more multiplexes or to clear some frequencies for other use? (52.3992,-0.7201)
| link to this comment |
I went to visit my aunt near Arundel. I took my MacBook and Eye TV. I found that I could receive all the multiplexes but there was something very odd. When I wanted to listen to the radio (Absolute Radio and Radio 4) I had to put the aerial in one part of the room but when I wanted to watch TV (BBC News Channel, BBC2, BBC Parliament and Sky News) I had to put it in another location. To watch ITV, Channel 4 or Channel 5 I had to put it in a third location, where other TV channels were corrupted.
What was going on? (52.3992,-0.7201)
| link to this comment |
I have two TVs and a computer (iMac) with a TV tuner card (external, Eye TV). I have always been able to receive all multiplexes on the two TVs, living room TV fed by roof-top aerial and bedroom TV fed by set-top aerial. However, until yesterday's retune I could only receive the two PSB DVB-T multiplexes on the computer. Now I can receive one more multiplex, the one that has Russia Today on it, and just using the set-top aerial, it breaks up and is barely watchable. However, I put the aerial on an antique silver salver and immediately noticed an improvement in reception. Improving the contact between the metal base of the aerial and the salver with a piece of aluminium foil improves reception of this multiplex to the same quality as that of the two PSB multiplexes.
Question 1. Why?
Question 2. Will using the salver as an aerial in contact with aluminium with steel on the other side cause any damage to it? It's an antique and probably worth a bit, if only for the silver value! (52.3992,-0.7201)
| link to this comment |
@ Michael Smith - perverse though it may seem, the signals for Channel 3 and others may be better if you attenuate them. In my living room I have an HD ready TV with a PVR, DVD recorder/player and an HD Freeview STB. I note that I get ITV 1 and ITV 1+1 on the TV, PVR and DVD but not on the Freeview HD box, which receives its feed directly from the rooftop aerial. I think that the signal degrades as it goes from one machine to the next, the evidence being that the TV and DVD player, which are second to last and last in the line, do not receive those multiplexes that are still on low power. (52.3992,-0.7201)
| link to this comment |
Friday 18 March 2011 12:01AM
Looking at the map comparing QPSK and 64QAM, it strikes me as absolutely obvious that QPSK should be used. 21 million households versus 16 million is a no brainer in commercial terms. The one big problem is the lack of coverage in a line from The Wash to The Severn. Do you think that some extra frequencies, perhaps channels 35 and 37 could be used to fill this and other smaller holes? It would also be nice to provide some coverage for Mid Wales and Herefordshire.