All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
Mary: At that location, chances are extremely good that you have too much signal even without a booster. If you were much further away, I would say that maybe the reflector is too short, but you should be able to use an indoor aerial at that location (or no aerial at all) and still have excellent results.
A wideband is completely unnecessary at Crystal Palace and it's unlikely that it ever will become necessary.
Remove the booster completely, it won't be doing anything useful and could be harming the signal quality.
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Stan Hill: Mendip has never previously used C48 or C52. If you are using a communal aerial, the distribution system might need retuning to amplify these channels instead of the old locations. If you had a similar problem in January when ArqB moved to C67, that's probably the issue now.
You might also or alternatively have another box, such as a Sky box or VCR, with an RF output on a clashing channel, most likely C43 or C47. RF outputs clash with the same channel, adjacent channels, and 5 and 9 channels higher. If you do, try turning it off if it's not used, or retuning it to C21 - this channel is unlikely ever to be used at Mendip.
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Stan Hill: 813 isn't a standard location for any channel. BBC News should normally be on 80. Anything stored in the 800s is a duplicate of something else, and the order they get stored will depend on the order they are found or the relative strength, when you retune.
It could be an indicator that your box doesn't handle the larger Network Information Table, or other extended service information, correctly. Digital UK have a partial list of equipment known to have problems at http://www.digitaluk.co.u…tnit and more information for specific boxes at Digital UK Retail - Troubleshooting guides .
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Chris.SE: A minor quibble, Oxford did not get a temporary mast to provide services while the main antenna was re-engineered. Instead the reserve antenna was used for all services. This is fitted *below* the FM radio broadcast aerials, which occupy a significant amount of space - the reserve is 55m lower down a 159m mast than the main antenna. This is the last resort should a future problem take out the main antenna or transmitters. The main antenna itself is designed in two halves and can be run on only one half, although (presumably) at reduced power. This redundancy is carried through to the combiner unit.
Unlike many sites, at Oxford, low-power DTT ran from the main antenna, plus an extra 'hat' on top of the old cylinder, with the possibility that a couple of multiplexes (1 and B) had an extra filler on the side of the mast, a little below the new reserve. That meant DTT was also quite seriously affected when the main aerial was being replaced.
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KB: Lyngsat says Novasports are on Hotbird 8/9, 13°E. Encrypted using Irdeto 2 - you can get an Irdeto CAM to plug into a free-to-air receiver at a number of UK websites (or at least they're priced in pounds).
Funny how UK channels are on a satellite further east than the Greek channels!
Nova are well aware of this situation, they carry the English commentary (which I believe is the Sky commentary!) on a second audio stream. All adverts and match build-up and review are in Greek (or were a couple of years ago).
It does test your knowledge of the Greek alphabet to figure out which channel is showing your team's match... as I recall, it was in the two seasons when I was interested.
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Suzanne: At 13km from a 100 kW transmitter you need a 14-element Yagi, tops. A 'contract' 10-element would probably have been fine. An indoor aerial will probably work well enough at this location.
I have to say that aerial looks pretty flimsy.
The difference between C60 and C59 at the moment is only 9 dB, there was a much bigger difference between adjacent analogue and digital channels before switchover (e.g. Channel 4 on C53 and Mux B on C52 differed by 19.2 dB).
The problem is that digital TV requires any amplification to be very linear - including automatic gain control and the internals of the tuner. If not, you get intermodulation - frequency-shifted copies of the signal in one channel, that then interfere with another channel. Most amplification circuits are approximately linear - near enough for reliable performance - in their designed input range. Go outside that range and they distort. It's that intermodulation that I think is happening to you.
IF your fitter had set up the signal levels at the recommended level for analogue, they should not now be so strong as to cause intermodulation. However, many fitters either set up the signals at the maximums for low-power digital, despite the large difference in levels between analogue and pre-switchover digital at Oxford, or just fitted the same aerial everywhere regardless of the requirements of the location.
Some boxes might have trouble with very different signal levels between multiplexes, say if their gain control circuits set the level based on the overall signal level, but then I would expect all the commercial multiplexes to fail, not just one. I didn't see very many reports of problems at Sutton Coldfield between stage 1 and 2 of DSO, which had the new BBC multiplex booming in at 200 kW on C40 and the old ITV1 mux (Multiplex 2) at 8 kW on C41 - a difference of 14 dB.
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R Lees: It's cost.
In 2007, the two transmitter owners, Arqiva and National Grid Wireless, published Reference Offers for Network Access, basically sample contracts for transmitting a multiplex. In those documents, the public service broadcaster outline costs - in 2005 prices - were given as £24.7m per multiplex per year, while the commercial multiplex operators were quoted £10.4m. If the costs were shared equally across all six multiplexes, each would pay £17.5m, so an increase of £7.1m (+69%) for the commercial operators, for an increase of potential viewers of only 8.8%.
There are 80 main transmitters and 1,074 relays. The main transmitters are higher-power, but there's a substantial capital cost of equipment required at each relay site.
No, the licence fee is the same, there is no rebate. The licence is for operating or installing a television, the money raised goes mostly to the BBC, and the BBC's public-service channels are all broadcast from all transmitters.
The BBC does own - through BBC Worldwide - half of UKTV, which runs the Dave, Yesterday, Really and G.O.L.D. channels on Freeview, plus a few more on satellite. The revenue from advertising feeds back into the BBC public-service broadcasting budget.
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Richard: I'm not sure what Mendip clash you're talking about, Mux 2 at Oxford was adjacent to Mendip Mux D before switchover, and the two stations ran like that for ten years since March 2001. Both got subsequent power increases, Oxford in August 2002 and Mendip some time in mid-2003. From January this year, Mendip C67 had a power increase from 10 kW to 26 kW so ArqB could launch in final mode, restoring Sky Sports. This would presumably be the upper limit that could be used.
People out in Swindon might have had a problem on occasion with adjacent channel interference (caused by filtering being imperfect - in the real world, some leakage into adjacent channels is inevitable - and a little cost-saving on using less complex filters where there isn't an adjacent channel at the same site). Someone in or near Beckley itself would be unlikely to have this problem except in incredibly rare weather conditions.
I'm really not sure what your issue was - some local source of interference does seem the most likely. If you're having increased problems now - the same on all multiplexes - I'd look into sources of impulse interference like a thermostat or other motor.
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Mike Bryce: Most likely explanations are either an overlap, with the box tuning in the wrong transmitter, or too much signal. See Digital Region Overlap and/or Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice .
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Tuesday 4 October 2011 3:23PM
Clive Jenner: I got that when Hemel Hempstead retuned a few weeks ago (14 September). HH simply retransmits what Crystal Palace transmits, so a change in the frequency information for HH had to actually be transmitted by CP.
I also have a PVR-9200T, but it hasn't prompted again since. Are you up to date? If you press MENU and go to System, Status, the versions should be:
System ID: 3020.0000
Application Version: PGXTF 1.00.23
Loader Version: A4.09
Update Date: 20th May 2010
If the versions are older than that, the current version is currently being rebroadcast. In the Software Update menu, make sure that it is set to automatically update at 4am. Make sure you put the receiver in standby before you go to bed, it will not update unless it is in standby.
That said, I think the change notification was only added in the that version.
As I recall, there are three options, Now, Later and something else. I pressed whatever would cause it not to retune at all, and never ask again (i.e. the third option).
Humax do recommend doing a Default Setting after installing that update. You might try doing one anyway. That will delete the future recording schedule and all channels, and all other settings - previous recordings are kept. I'd particularly advise moving the RF output away from its default as it clashes with analogue Channel 5 - I've set mine to UHF 53.