All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
Peter Musau: Look for an option in the TV's tuning menu to select PAL B/G.
Various different standards for picture information (e.g. number of lines, frame rate, colour encoding) and the location of the sound carrier(s) have been used around the world. See World Analogue Television Standards and Waveforms for full details.
Basically, a TV built for UK/Ireland System I expects to find the mono sound carrier at 5.9996 MHz above the vision carrier. For B/G it's transmitted at 5.5 MHz, so the TV can't find it. NICAM stereo wouldn't not be found either because again it's at different frequencies (I don't know if Kenyan channels use NICAM). The UK has never used middle-side stereo as has been used in Germany (it's the same technique as FM stereo radio uses).
Also, if the TV was only built for the UK, it may only support the UHF band and won't find transmissions in the older VHF Band I and Band III, which I believe Kenya still uses at present. We now don't use Band I and use Band III for DAB radio. (RG47SH)
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Charlotte mooe: BBC Two analogue has been switched off for good at Sandy Heath and Nottingham transmitters. To watch BBC Two, you need to select the digital tuner. Press TV, or SOURCE, or INPUT, or MODE on the remote to switch from analogue to digital tuner. Panasonic have made a variety of Integrated Digital TVs over the years, so I'd really need a model number to tell you exactly which buttons to press. The instruction manual also has the information. They have a pretty good archive of instruction manuals on their website, or try TV Re-tune productmanuals the 13th, the other analogue channels are turned off for good. If all BBC digital services are missing (apart from possibly BBC Four for the next two weeks), and they were watching Freeview before (able to watch BBC Four), we need a full postcode to figure out what the problem could be. It's most likely that signal levels are now too strong and you need to remove amplifiers or boosters, or add an attenuator, to bring them down to levels that won't overload the TV. (RG47SH)
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Racundra: It's done in two steps so they don't get a sudden flood of calls all on the same day.
High-power BBC services start up tomorrow. Retune after 6am, if you're using Ridge Hill itself - some relays will be later (see Digital UK - Relay transmitter switching times .
All other services increase on the 20th. (RG47SH)
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Sleo: ITV1 remains on analogue at Luton until the 13th. Only BBC digital services have started up so far.
The predictor suggests it's more likely that you're using Sandy Heath than the Luton relay. In that case, see Single Frequency Interference, and see whether it improves after switchover completes next Wednesday.
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Kelly: The transmitter is more-or-less due northwest of you. Try to aim the aerial in that direction and ensure that the elements are flat, rods going side-to-side. More height will usually help but keep it away from any metal objects. You probably will have to try several different locations to get good results.
It could be that your bedroom is simply on the wrong side of the house, and signals would have to travel through the other rooms before reaching yours.
As I said, a proper aerial will usually help. Consider asking an installer about a multi-room installation. A roof aerial should give excellent results.
The Divis transmitter will increase in power next year, when the analogue signals are turned off. We don't know the exact dates yet, and Ofcom are still to publish the final channel allocations and power levels for the Ulster TV region.
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Alan: One aerial can feed as many TVs as you need it to. Just ensure that you use proper splitter devices rather than trying to wire more than one cable into the splitter.
Whether you need an amplifier depends on the signal level you have. To feed five TVs you need a 6-way splitter, and each output will have 10 dB less signal than the original level you received. The new power levels are about 9 dB more than the old ones, so if you had reliable Freeview before switchover it's likely that there would be enough signal to avoid adding an amplifier.
There's also a reasonably good chance that your aerial was overspecified for the job and has too much gain. Splitting the signal from it could actually help!
If you do add an amplifier it's recommended that you only add enough amplification to offset the loss in the splitter.
Do note that while the PSB muxes (BBC A, D3&4, BBC B/HD) get their final channels and power levels next Wednesday, the commercial multiplexes will get their full power increases only in September, November and next year.
I'd see how the ITV1/C4/C5 PSB multiplex works out on the loft aerial, and make a decision after that. I think it's quite likely to work at least as well as the BBC multiplex. As Brian says, though, it may not work in the frequency range that the commercial multiplexes will be using.
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M
2011 switchover week two: The Wrekin and Ridge Hill transmitterTuesday 5 April 2011 10:47PM
Reading
Aerialman: they double in power, but go back into 64QAM 2/3 mode, from 16QAM 3/4. The higher-capacity mode requires *at least* 3 dB more signal-to-noise ratio. Basically the power increase is to offset some of the loss of coverage due to the mode change.
The simulation results in the DVB-T spec are, by the type of simulated noise:
Gaussian (pure white noise)
16QAM 3/4: 12.6 dB C/N required
64QAM 2/3: 16.7 dB
Difference: 4.1 dB
Ricean fading (some reflections, but dominated by line-of-sight path)
16QAM 3/4: 13.4 dB
64QAM 2/3: 17.3 dB
Difference: 3.9 dB
Rayleigh fading (multiple strong reflections, no line-of-sight)
16QAM 3/4: 18.1 dB
64QAM 2/3: 20.3 dB
Difference: 2.2 dB
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M
Another government U-Turn - this time on FM local radio? | DigiTuesday 5 April 2011 11:10PM
Reading
david: The authorities are too chicken to break the few million DAB-only radios out there.
Oddly, for TV broadcasting they're not afraid to break the 2k-only Freeview boxes, broke some other boxes by splitting the NIT across more than one data packet, and are prepared to offer HD services through yet another incompatible scheme.
My view is that DAB has failed. It won't reach the 50% target. We have to admit the failure quickly, ban any new DAB-only radios from being sold, and start converting. Trouble is, you can't convert a national multiplex on a Single Frequency Network piece by piece. You have to do it overnight.
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M
My Freeview box has no EPG, is blank on FIVE, ITV3, ITV4, ITV2+Tuesday 5 April 2011 11:12PM
Reading
Steve Freear: we really need a full postcode to figure out the signal strengths.
Only the BBC channels have gone to high-power digital so far. The ITV1/C4/C5 multiplex goes high-power next Wednesday, and the HD services start up. The other three multiplexes will go high-power in September, November, and mid-2012.
Generally you will get more reliable results with a roof-top aerial.
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Tuesday 5 April 2011 2:28PM
Alan T: Don't trust the list here. The terrain data is just too inaccurate and it doesn't take account of other transmitters on the same channel. Instead, use the Digital UK postcode checker.
This shows that Sutton Coldfield is your best option now and after switchover completes. If you want East Midlands news rather than West Midlands, you could also use Waltham.
There may be a basis for the order displayed, but I can't figure out what it is.
If analogue is snowy, your problem is probably a deterioration in the aerial or cable's performance. Check that the aerial is still pointing where it should be (299° for Sutton Coldfield) and is intact, and check for broken, loose or disconnected cables.
Predicted analogue signal levels are actually above the recommended *maximum* level for analogue with any aerial at all - using Field Strength Calculator I get a prediction of 84 dBuV for BBC Two (C40 at 1000 kW) using an aerial with 7dB of gain and 10m of cable. The recommended range is 60 to 80 dBuV, as it says at the bottom of the page.
However, according to their terrain information, there is a hill just to your north-west blocking direct line of sight, which reduces signals a fair bit. (RG47SH)