All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
Fee: for storm damage you could see whether the buildings insurance covers it.
Aerials aren't actually that expensive, ranging from £22 for a log periodic, £26 for an 18-element Yagi, up to £65 for the whopping great X-type aerials (that very few people need). Parts generally aren't replaceable. (These prices from Online TV FM DAB Aerial sales )
The reflector is the part at the back which ensures that only signals from in front of the aerial are picked up, and it also plays a large role in the gain on the lowest channels. Wideband aerials are often compromised at low frequencies anyway.
Replacement of a like-for-like aerial shouldn't need any extra planning and testing, but the installer will have a standard call-out charge and an hourly labour charge. The charges will probably depend on how accessible the aerial pole is. (RG47SH)
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Jon: Could you please provide your full postcode? That allows us to see how good the coverage is where you are.
Was there already a TV in the room before, and was the picture clear on that TV? Is the TV connected to the roof aerial, a loft aerial, or an indoor aerial?
If the same aerial feeds the main downstairs TV, do you get a clear picture when you use the analogue TV functions? If that set has a Freeview tuner, do you get reliable Freeview service on it?
Generally if you're feeding more than one room, you get best results using an amplified splitter, fitted as close to the aerial as possible, with just enough amplification to offset the extra losses from splitting the signal. Adding additional aerials can cause problems with the first aerial - they are designed to be fitted with a lot of free space around them.
If you have enough signal, you can use a passive (unamplified) splitter.
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Kevin Hodges: It means that the centre frequency of the transmission is slightly (167 kHz / 0.167 MHz) above or below the normal centre frequency of that channel.
Before switchover, it's used to get out of the way of an adjacent analogue transmission from the same site. If one channel has an offset, usually the next channel has one as well if it's used at the same transmitter. Mux A has a + to avoid C4 analogue, then Mux 1 has a + because of that, and Mux D because of Mux 1. I'm guessing that BBC One analogue has a reduced lower sideband to avoid clashing with Mux D.
After switchover, it's usually only used to ensure that whatever other system is licenced to operate in the adjacent band doesn't cause problems. You usually see C21 with a + offset to avoid problems with TETRA, for example. C60 has a - to avoid the 800MHz mobile phone band that will be auctioned shortly after switchover completes. Channels 31 to 38 are due to be released (the 'Digital Dividend').
The Caldbeck transmitter therefore uses C30- to avoid whatever gets licensed at 550 MHz upwards (C31). This causes a cascade of each lower service also having a - offset. There's a potential problem for any local service here as it's been allocated C21 which would normally have a + offset, but that would collide with the Scottish BBC service on C22-. That's the most extreme case I'm aware of.
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Briantist: The mobile phone companies got burned with the 3G sale at 2.1GHz. I don't think anyone expects them to bid nearly as much for the 800MHz lot.
There is no mobile phone equipment anywhere in the world designed to operate at 550-614 MHz. No other country is releasing this spectrum. It's highly unlikely that anything would be designed just for the UK. Most of the responses to Ofcom's consultation from mobile networks simply said 'reserve it' (i.e. think about it later) and from hardware manufacturers, said 'we're not planning any hardware for that band'.
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M
Sandy Heath (Central Bedfordshire, England) Full Freeview transWednesday 30 March 2011 1:58PM
Reading
Dave Kimber: there have been some reports of this on some Sony TVs up in Scotland. It may be a recurrence of a problem they had with Humax equipment a week or so ago. They seem to be using some new code for the 'Press Red' popup that appears during the news, or '(Red) SPORT' in sports programmes.
My hypothesis is that they've changed which MHEG program ID to run automatically when you select the channel, and the boxes still have a cached copy of a previous program with that ID that did something different (probably used for returning to the service you were watching when exiting from an interactive stream).
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M
2011 switch-overs start today at Sandy Heath, Nottingham | SwiWednesday 30 March 2011 2:24PM
Reading
Leesa: if you retuned before 6am, they may not have finished getting everything in its final configuration. Try retuning again.
Otherwise, we really need a full postcode to see what you should expect to receive.
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Bob: start watching a Multiplex A channel, e.g. ITV3, and go to the box or TV's System Status/Signal Strength screen. See what channel number it says. If it shows 26 they've forgotten to switch something off. If it shows 29 your box automatically retunes itself. If it shows something else, you're picking up Multiplex A from a different transmitter.
It's just possible that you were getting the 30 March popups from Sandy Heath, not from Waltham. I don't think they were running popups from Waltham for this early retune.
If you provide a full postcode I might have a better idea what's going on.
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ian: I believe the TopUp TV Anytime service information is broadcast periodically overnight. Your box is probably showing you information that it saved from before the retune.
A full retune (factory reset, first-time installation) should bring Mux A back. See www.tvretune.co.uk if you don't have your manual available.
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Paul C: I thought that the Humax HD boxes now asked you which region you want to save.
It looks like where you are, you have a choice of three transmitters: the main West-region mast at Mendip, the main Welsh mast at Wenvoe, and the Bath relay (Freeview Light, carries only the three PSB multiplexes). You should get good or very good results from all of these.
There was no need to replace your aerial. Most of the benefit from the 'high gain' aerial (and most of them have no higher gain than an 18-element Yagi) is lost by putting it in the loft. Putting the aerial outside prevents a lot of problems with signals reflected off interior surfaces and attenuated by passing through roof tile and brick. Reflections can alter the signal's polarization too, so you pick up more spill-over from the other polarization.
A wideband aerial will cause you problems in this area, not solve them. The grouped aerial would have been picking up Mendip and rejecting Wenvoe and Bath. Bath requires a Group A aerial oriented vertically, Wenvoe needs a horizontal Group B, and Mendip a horizontal Group C/D.
Boosters generally add noise and where you are, you shouldn't need one. I'd start by disconnecting that.
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Wednesday 30 March 2011 8:33AM
Nick:
That information comes from NGW's Interleaved Frequencies analysis of what channels new multiplexes could potentially be launched on to reach the maximum amount of the Crystal Palace coverage area.
I'd be surprised if enough additional TV services were ready to launch by mid-2012 to require a second new multiplex - C29 (NEW7) would be preferred, but even that isn't ready to go at switchover. There's also a strong chance that the channel plan would have to be redone since the plan it was based on wasn't final.
The plans were made on the basis that while C42 is strictly outside Group A, many Group A aerials have usable gain at that frequency. It's not a sharp cut-off at C38. However, looking at some gain curves I think they're being optimistic: Gain (curves), Again (RG47SH)