All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
Penny: Digital UK's prediction for you is very good across the board, so you really shouldn't be having problems. Some people found that the replacement aerial at the transmitter resulted in *more* signal than they had previously, and therefore had to remove boosters and/or add attenuation.
Oxford gets ITV Meridian news ever since they closed down the short-lived ITV Thames Valley service in 2009.
If it's only Mux 2 that's affected, it could be a cabling issue. If water has got into the cable, the loss in the cable increases, and loss at higher frequencies is greater than at low ones. This can happen if an outside junction box, masthead amplifier, or the connection box on the aerial is not properly sealed, or if the insulation on the cable is damaged, either by rubbing against brickwork or tiles or simply perished due to UV exposure. Cables should be properly secured about every 15cm with cable clips as they travel over tiles and down walls, they should not be able to move.
You could also be suffering from impulse inteference, which is more of a problem in the 64QAM mode used by Mux 2 and Mux A. Check whether the problem occurs when a thermostat or motor switches on, for example central heating pump or hot water heater. If so, get a heating engineer to check the pump. Mobile phones can also cause problems - keep them well away from the TV and cables. Better-quality cables (usually termed 'satellite-grade') are less susceptible to picking up interference.
At switchover, you must do a full reset on both days as the channels are all moving to different frequencies - they replace the analogue transmissions. Analogue channels are completely switched off - it is all digital from now on.
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Roelof Kramer: Digital UK's predictor reckons you have a slightly better chance of reliable reception from Oxford than from Hannington. While there is a hill blocking line-of-sight from Oxford, there is actually also one blocking line-of-sight from Hannington, it's just further away (Thurle Down, north-west of Streatley).
It is possible to have too much signal. Many people specifying new equipment add amplification completely unnecessarily. I would start by bypassing the masthead amp, and see what the results are.
A professional installer would use a strength meter indicating the Modulation Error Ratio - an indication of how much the signal is distorted from the ideal - to decide what size aerial to use and determine whether any amplification was needed. Digital UK's predictions are based on 10 dBd of gain from the aerial and 3 dB of loss in the cable.
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Hal: For communal aerials, check with your landlord or agent, or the residents' association. See PARAS - Professional Aerial Riggers Against The Sharks for more suggestions.
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Steven C: Did you get all the BBC channels between the first stage on the 8th and the second stage on the 22nd? If so, your box is certainly 8K-capable.
Did you retune on both days? All the digital signals moved to new frequencies, the PSB channels taking over the old analogue frequencies (which were the best allocations in this location). You would need to have done a full reset, also called a first-time installation, a full retune or a default setting, to ensure that the box forgot about the old location for the channels. Some won't save channels that they already think they know about.
Many people find that they have too much signal after switchover. If you have a booster or amplifier, remove it. It shouldn't be necessary any more (though you haven't provided a location, so I can't check). Signal levels might still be too high even after this, you can add an attenuator to reduce them further.
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John Fisher: Satellite tuners need two connections as they aren't just inputs. They actually carry some control signals back to the low-noise block converter (LNB) on the dish, which tell it whether to select low or high range, and horizontal or vertical polarization (there are two receiving elements, one for each polarization). Each tuner in each receiver has to be able to individually control these settings, for its connection, to be able to access all the channels.
UHF aerials are completely dumb devices. They don't do any frequency conversion, and they are installed in one polarization, whichever is appropriate for your local transmitter. Therefore you can split the connection as many times as you like (though you do lose some signal on each split). The receiver just splits the signal between the two tuners internally.
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Mike O'Pray: In your area, Digital UK's predictor says that you won't get anything much on Mux A/SDN and Mux C/ArqA because the channels from Sandy Heath clash with two of the analogue channels from Sutton Coldfield. However, ArqB is expected to be OK - high probability of reliable reception - *if* you have the right aerial and the system is in good condition.
On 31 August, Mux A/SDN moves to a different temporary frequency, C31, after that is released by Waltham. This should then be clear enough to receive reliably.
On 14 September, Mux D/ArqB moves to its final frequency (C48) and power level. Mux C/ArqA then takes over Mux D/ArqB's current frequency. Again, that puts the prediction for all services over 90%.
If Mux A and Mux C are working reliably at the moment, or at least more reliably than Mux D, there is a different problem. Honestly, it's easiest if you call out an installer to check the levels, the connections, the cables, etc.
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James Donnelly: The Chelmsford transmitter has only ever provided analogue Channel 5. Your other analogue signals, and any digital signals, will be coming from somewhere else.
I believe Chelmsford UHF TV transmissions will be switched off completely when Sudbury is switched over, despite Chelmsford technically being a relay of Croydon. I'm not sure what purpose the Chelmsford C5 transmitter serves - possibly the fact that Sudbury's C5 transmitter was one-fifth the power of the other four channels meant that another transmitter was needed to serve this area, if the aerial was pointed to Sudbury.
Croydon's transmission power for C5 is the same as the analogue power level for the other four channels from Crystal Palace.
The prediction for your postcode from Sudbury is for reliable results on the PSB muxes (Mux 1/BBC A, Mux 2/D3&4, and Mux B/BBC B/HD) and Mux A/SDN, but variable, poor, or no prediction for Mux C/ArqA and Mux D/ArqB, immediately after switchover. This will continue until after Dover and Bluebell Hill switch over next June, when the Sudbury COM muxes move to final channels and power levels.
From Crystal Palace, all multiplexes are good *now* except for Mux 2 and the early HD service, which are both shown as variable. At switchover in April, everything goes up to good, over 95% probability.
The ultimate predictions are about the same from both transmitters.
If you're currently using Crystal Palace, don't bother retuning in July. Nothing changes for you. CP will get to its final configuration slightly sooner as well. Look out for adverts for the London TV region switchover, rather than Anglia.
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Briantist: I believe the switch-off date for Chelmsford should be 20 July 2011, not April 2012, based on Ofcom's latest Digital Switchover Timetable at http://licensing.ofcom.org.uk/binaries/tv/sup_dso/dso-timetable-v2.pdf .
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Mr R Pierrepont: While there is ongoing engineering work, it should not prevent analogue reception. They are only supposed to reduce power by half (3 dB) if there is any reduction, though some interruptions are possible.
Given what you say, I would check for a broken or disconnected cable somewhere in the system.
The notification of engineering works has been very poor all round, at all sites. Unfortunately Digital UK only publish the information - that they are given by the transmitter owner/operator, Arqiva - a week at a time, so we really don't know how long it's going to go on for.
The TV licence is for owning a TV and therefore you are not entitled to any rebate.
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Friday 24 June 2011 5:29PM
Ruth: Check that the SCART cable is properly plugged in? If you're using an HD box with a DVI connection to the TV, the audio would need to be carried on a different cable - again, check that it's properly connected. HDMI cables carry sound on the same cable as the picture.
If you're using an RF modulator, and tuning in a channel on the TV to the box, ensure that the box and TV are both set to PAL I/System I/UK mode.
Also check that the box and TV are not muted, and if the box remote has a separate volume control, check that the TV and box volume controls are set appropriately. I set the box's volume control to maximum and control volume from the TV remote.