All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
Steve: Some boxes need a full reset to clear out any existing information. It might also be called 'Full Retune', 'Default Setting', or 'First Time Installation'. Check TV Re-tune to see if a guide is available.
If you've already done that and the problem still occurs, check to see if the box has an automatic overnight retune option. It may be retuning itself to the wrong transmitter.
If you can't find that option, or turning it off doesn't help, check whether there are additional versions of the channels in the list - often 800 onwards. If there are, try doing a manual retune - do the First Time Installation with the aerial unplugged, then plug the aerial in and do a Manual Channel Scan on C53, C39, C47, C51 and C41. Don't bother scanning C44, it now just carries duplicates of BBC Four, CBeebies, BBC Parliament and the BBC radio channels. (It also carries Sky Sports 1 and 2, which are encrypted, so no loss.)
Some equipment gets confused by a mix of 8K and 2K modes across the multiplexes. If this is the problem, it will go away after the second stage on 21 September.
| link to this comment |
dave: I think broadcast TV will be around for a while yet. So far the mooted replacement of linear channels with on-demand content just hasn't happened. People still seem to want to be entertained by a selected programme of content rather than making their own choices. (It's not as if they haven't been able to go out to the cinema or theatre for the last 60 years, after all!)
'IPTV', linear channels over the Internet, have a large stumbling block - every viewer has to receive their own copy of the content, individually addressed, meaning that the bandwidth required is the bit rate of the content *multiplied* by the number of viewers. True broadcast, sending to all users connected, is not allowed outside your own network (routers will not forward broadcast packets). A feature called 'multicast' *is* defined, but it requires routers all the way from broadcaster to receiver to process group join/leave requests and know to forward the multicast packets all the way to the receiver. That isn't yet widely available - it's likely to be restricted to certain ISPs at first, and only certain broadcasters who've made arrangements with those ISPs. YouView boxes are likely to be available only from ISPs at first, those who have actually sorted out their networks to support multicast.
| link to this comment |
bernard hunt: It's just a power increase, not a change of mode or frequency, so it doesn't require a retune - though viewers that can't get it now are likely to have to retune to get it after the power increase.
Ofcom's Table of Digital Terrestrial Stations does show the restriction to 5 kW as ending on 12 October. It can actually happen any time after Oxford finishes using C29 on 28 September, but co-ordinating with Waltham SDN power-up (also on C29) is probably a good idea.
| link to this comment |
Briantist: Sandy Heath ArqA does move to C67 overnight, but you haven't listed this at the top of the page.
| link to this comment |
Whiskeymac: All multiplexes from Rowridge currently broadcast at the same power level, although multiplexes 2 and A use a different mode that requires greater signal quality for reliable reception. Mux 2 carries ITV1, ITV1 +1 and ITV2, while A carries ITV3, ITV2 +1 and CITV. ITV4 is on Mux D.
Mux 1 got the best frequency allocation, then 2, A, B, C and D, but due to the mode differences, B C and D can sometimes be better than 2 and A.
On 7 March 2012, Mux 1 and BBC Two analogue close down, and high-power BBC A starts at 10x current power level.
On 21 March 2012, Mux 2 and B and the remaining analogue channels close down. High-power D3&4 (replacing Mux 2) and BBC B/HD (replacing Mux B) start up at 10x current power level.
Because the allocated channels clash with various relays in London, the commercial multiplexes cannot go full power until 18 April 2012.
Rowridge will transmit on both horizontal and vertical polarization - for aerials oriented horizontally (elements going side-to-side) and vertically (elements going up-and-down). On horizontal polarization, the polarization used currently, the PSB multiplexes will be full power but the COM multiplexes will only be one-quarter of that power (50 kW). On the new vertical polarization, COM power levels will be the same as PSB power levels, both 200 kW.
Digital UK predict that your reception of Mendip should be better than that from Rowridge, even with a vertically-polarized aerial. Rowridge COM multiplexes will be poor, both on VP but especially HP, because Stockland Hill has been assigned the same frequencies for its COM multiplexes.
| link to this comment |
Liam McLoughlin: Sounds to me like your communal system wasn't retuned properly after switchover, and it's not amplifying C61 to the same level as C62. Do check for any other equipment of yours that might be outputting on C60 or C61, such as an old VCR, a Sky box, or your Freeview box if it has an RF modulator - often the filtering isn't very good and it can interfere from a few channels away; using a much lower channel should give better results.
If you're certain you don't have any other equipment with an RF modulator, check to see whether the analogue tuner on the TV will show a picture on C61. If it does, probably the communal system is allowing that through from someone else's flat - report this to the landlord or building manager.
See PARAS - Professional Aerial Riggers Against The Sharks for some advice on who to contact regarding the communal system.
| link to this comment |
Philip Howe: It looks like Preston should be a strong signal area, so I'd go with a 40-element log periodic. See Online TV FM DAB Aerial sales for one seller and what you're looking for.
Winter Hill only requires a Group C/D aerial at present, and the proposed local service is also in group, but there's a possibility that new services could start in the C31-C38 range, which a Group C/D aerial wouldn't cover very well. Wideband aerials - and the Log40 is wideband - cover the whole range from C21 to C68, and aren't that much worse than an aerial designed for only Group C/D over that group.
For advice on fitting a loft aerial, see Loft and indoor aerial installations for TV, FM and DAB and http://wrightsaerials.tv/….pdf .
If fitted outside, you might not even need as much gain as the Log40.
There may be holes in coverage across the city, so do check the Digital UK postcode checker, or if you provide your full postcode here, one of us can take a look for you.
| link to this comment |
Alan Hewitt: It reflects the situation in 2007 before the switchover programme really got going. Brian has put an additional line in for transmitters that had major changes early on - Rowridge, where the line-up changed a lot, and Sheffield, where one mux had to move to squeeze in HD at Emley Moor - but mostly the pre-switchover changes, and any parking channels used after switchover, have not been listed.
| link to this comment |
Mark Fletcher: 'Useless' is a bit strong. The CAI Standard 1 specification is 10 dBd minimum in Group A, 11 dBd in Group B, and 12 dBd in Group C/D. These are the figures used in the Digital UK postcode checker, which allows for 3 dB of cable loss in Group A, 4 dB in Group B and 5 dB in Group C/D for a net 7 dBd across the whole width.
Even the massive XB22WB doesn't manage this below C30, offering only 7.5 dBd at C21.
However, Standard 1 is intended for use only at the extreme edge of the coverage area. Standard 2, for use in medium signal areas, requires 7/8.5/10 dBd in the three groups for a wideband, a Group A or K aerial must offer 0.5 dB more in group A. The Log40 achieves this standard up to C64; although it doesn't quite manage it above that, that's probably a good thing considering C61-C68 are released for 4G phones!
The CAI also define Standard 3, which contract widebands can achieve as it only needs to deliver 5/7/8 dBd. Again, a Group A or K Standard 3 has to deliver more gain in Group A than a wideband, 6 dBd. Standard 4 is wideband-only and covers small logs delivering 7 dBd in all groups.
I would really expect anyone who actually needs a Standard 1 aerial to get Belmont would get better results from a different transmitter anyway!
| link to this comment |
Monday 12 September 2011 3:34PM
The speculation on Digital Spy was that there is a lockdown on alterations while the Olympics and Paralympics are happening. The Paralympics end on 9 September 2012, so this really is the first opportunity!