All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
Simon: I'd look for another device with an RF output - perhaps one tuned to C36. See Single Frequency Interference for the types of device that might be doing this.
Even the box's own output might be causing it - my Humax PVR-9200T's RF output defaults to C36, despite the high likelihood of clashing with analogue Channel 5 at a large number of sites (well, before switchover started anyway).
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Lou: If there is an aerial socket, it's likely that there is a communal aerial system already. Contact your landlord or agent to see whether they have made provisions for digital TV already, and how they will handle switchover. If *analogue* TV doesn't work, definitely get in touch - check with other residents to see if it's a common fault.
See also PARAS - Professional Aerial Riggers Against The Sharks for general advice for tenants.
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J N Collis: Firstly, make sure you do a full retune from scratch. The option might be called full reset, First Time Installation, Default Setting, 'Virgin Mode', Factory Reset, or something similar depending on the box or TV. You may find instructions at TV Re-tune . Newer equipment (since 2009) should have included a leaflet specifically telling you how to retune at switchover - do the same now.
If that still doesn't help, and it's only the channels on the SDN multiplex that are affected (see the Lark Stoke transmitter page), look for any piece of equipment with an RF output, such as a Sky box or an old VCR, or even the Freeview box itself, and make sure that is set to a channel well away from any multiplex. Above C50 is probably sensible. The RF output can cause problems on the tuned channel, on adjacent channels, and on channels 5 and 9 higher than the selected channel.
Lark Stoke never carried analogue Channel 5, so even very old equipment could still be set to output on C36, which is very likely to cause problems with C41.
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RobWhitwell: Does anything else on the SDN multiplex work? For example, ITV3, Quest, Pick TV? If they do work properly, switch to ESPN, then press MENU and go to Status, Signal Detection. If that says it's using channel 31, then it's probably an issue with the CAM or the viewing card. Try turning off the PVR using the switch at the back, unplugging the CAM and removing the viewing card, turning on the PVR, turning it off again, and plug the CAM and viewing card back in.
If it's not shown as using UHF channel 31, try pressing MENU, then going to Installation, then Default Setting, to wipe all channels and retune from scratch. If, after that, it doesn't show as C31, do the Default Setting again but this time don't save the results of the automatic tune. Use Manual Search to scan C24, C27, C31, C48 and C67.
The reason for this is that the PVR-9200T appears to just store the first version of the channels that it finds, rather than the strongest or best quality. In the recent weather conditions, signals from Crystal Palace - which uses lower channel numbers - could be stronger than usual.
It's also worth checking that the PVR-9200T's RF output is well away from the desired frequency range. I'd put it around C55. The setting for this is in Preferences, UHF Output. The Default Setting option resets this to C36. This shouldn't clash with anything that you're using, but it can't hurt to keep it further away.
If signals from CP *are* travelling further than usual, it could simply be a clash with the Crystal Palace 'temporary' HD service, which also uses UHF channel 31. In this case it may come and go with changes in the weather. The problem will ultimately be resolved when Crystal Palace finishes switchover on 18 April next year (and therefore stops using C31).
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Christopher: If that's her postcode then yes, it is expected to give good results.
An aerial upgrade should not have been necessary if analogue signals were clear. It could have resulted in too much signal. Or, it could mean that signals from Divis are picked up strongly enough to be stored in preference to those from Limavady. It may be worth checking whether another version is present somewhere else in the programme guide that works better. If so, a manual retune should sort it out - see Digital Region Overlap for other suggestions.
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Steve P, RobWhitwell: C67 is definitely in use, it carries Multiplex C until after Tacolneston's DSO. It will move to its final channel, C52 (becoming ArqA), on 23 November.
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Frances et al: it's *probably* an error at Sky's broadcast centre or Arqiva's multiplexing centre. The mention of a delay and 'press red' suggests that it might be a bug or incompatibility in new MHEG software for the Sky Text service.
You could try doing a factory reset on your box. This might also be called a full retune, first-time installation, 'reinstall all channels', default setting, or 'virgin mode'. If you've needed to do a manual retune in the past, you will need to follow whatever steps you did then.
Richard and John: If you did a full retune/factory reset at the last round of changes at your transmitters, I'd be very surprised if the box had managed to screw up its programme guide this soon. That would point to a general fault in transmission.
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jb38: C59 is the only one of the lower-power multiplexes adjacent to another mux. Even at its current lower-than-final output it is more than twice the power of pre-switchover Multiplex C, and should have similar noise characteristics: though the relays at Lambourn, Chisbury, Hemdean and High Wycombe are closer than the nearest relays that previously used C51, Chisbury and High Wycombe will continue to use C59 after DSO, so I have to assume they aren't a major problem. ArqA does need a bit more than double power compared to Mux C, due to the mode change, but it should be roughly equivalent in coverage.
Given all that, I suspect people having problems with C59 are quite likely to have too much signal - see Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice for more information.
Otherwise I'd be looking for a device with an RF output on C50, C54, C58 or C59 which could be generating local interference. I would expect other multiplexes to suffer as well, though, at least with some of those frequencies. See Single Frequency Interference for the sort of thing to look for, and don't rule out your Freeview box itself, it may have an RF output particularly if it's an older model.
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Tim, Suzanne, Simon, Ron Valentine: Having looked at the Digital UK predictor's results, which show 99-100% probabilities across the board, the problem is very likely indeed to be too much signal.
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Monday 3 October 2011 12:19PM
Mark Heselden: The boundaries between this site's predicted 'best' area for one transmitter and another are fairly arbitrary and probably wrong - like most of the predictions, because far too much of the information is kept private by the broadcasters/transmitter owner.
In this case, it's because the coverage area is divided - by the tool that generated the map - between Crystal Palace and Croydon. Croydon only normally transmits Channel 5, although in a dire emergency it can transmit the main four analogue channels (Crystal Palace's own reserve antenna and transmitters would have to fail first). So this line is completely erroneous.
There's an analogue coverage area map dating from the 1980s at mb21 - Transmitter Information - Crystal Palace - this was measured, rather than predicted. Post-DSO digital TV coverage should be substantially similar.