All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
Michael: Can you provide your full postcode? It's worth checking first if you're expected to get a service yet, will have to wait for switchover, or whether it will never work that well. If you're in an area known (or believed) not to be covered, it's possible that the installers won't bother with the query. You could try looking at the Confederation of Aerial Installers directory at Directory . Search for Type 'Installers: Domestic' in your county. Or, try the Registered Digital Installers Licensing Board list at http://www.rdi-lb.tv/ If you're determined to go ahead and do it yourself, I suggest reading Planning Your TV Installation (RG47SH)
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David, George Buchanan: the only DVB-S2 transponders on Eurobird 1 are this one carrying C4 HD, and another at 12726V. LyngSat.com is showing that it broadcasts a BT Tower HD test card on stream 54515.
If your receiver has trouble with that, it may be that it's not able to handle the DVB-S2 mode they've used.
You should also check whether you can see the SD channels on 12643 H and 12643 V. If there's a problem here, there'll be a problem on C4 HD as well. Most likely this would be caused by too long a run of cable, poor quality cable, or damp in the cable - higher frequencies travel less well than lower ones.
Also check whether anything over 11700 MHz is watchable. Try BBC News or BBC Parliament. If those don't work, something could be blocking the 22 kHz tone that the TV uses to tell the LNB to switch to high band.
Tech detail: the LNB does the first stage of tuning because the very high frequencies used directly by the satellites just won't carry on the cable. It has two 'local oscillators' for low and high band, at 9,750 MHz and 10,600 MHz respectively. The signal on the cable is the satellite frequency minus the local oscillator frequency, 950 MHz to 2,150 MHz. These are chosen because they're above the UHF TV band, so you can carry UHF TV and satellite signals on the same cable.
It occurs to me that these intermediate frequencies are pretty close to the mobile phone bands. If you have a 3G phone, which uses frequencies in the region of 2.1GHz, make sure it's well away from the TV!
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George Buchanan: It looks like southwest Scotland is still within the highest contour on Eurobird's fixed beam's footprint.
Eutelsat satellites : EUROBIRD 1 satellite at 28.5 degrees East
I don't think you'd need a bigger dish. (RG47SH)
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M
Crystal Palace (Greater London, England) Full Freeview transmitSaturday 2 April 2011 6:00PM
Reading
Kieran R: I really can't offer any other advice. The signal strength is either too low or the level of interference too high - probably both - for services from Crystal Palace to be reliable at the moment. It will vary over time, because the signal strength *does* vary with changes in weather conditions, including as the atmosphere warms in the morning and cools at night. This is taken into account in the predictions - it's why Digital UK give quite a conservative prediction to the general public, and why the trade view is expressed in probabilities.
Your options are to stick it out for about a year until Crystal Palace switches over (but you might not get mux A, C or D), put the aerial on a longer pole to see over the trees, move the aerial to a different point on the building to see around the trees, cut down or prune the trees, or get satellite or cable.
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Christine: Good? Assuming you're talking about the level of Mux 2, that's about 20 dB too high. Remove any boosters or amplifiers, then if it's still too high, add an attenuator. You're looking for somewhere between 45 and 60 dBuV (some say 65 as the upper limit).
Signals at switchover will be 10 times - 10 dB - stronger than they are now.
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David Taylor: HD transmissions start on the second DSO day, 28 September 2011.
At Oxford, all multiplexes move to their final channels and modes at switchover. However, the commercial multiplexes (SDN, ArqA, ArqB) will be restricted to 12.5 kW until 2012, after March. They will then reach their final power level of 50 kW. We won't know the full details until the London region dates are published on Thursday, and possibly until the rest of the Meridian region dates are published.
It looks like it's to protect the Assendon and High Wycombe relays, though Hemdean may also be affected.
There may still need to be a subsequent retune to move the SDN multiplex from C62, unless they sort out the plans before switchover. There were some very late changes at Dallington Park and Luton relays to avoid using C62 (in fact they're using the channel for the next two weeks until DSO2).
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Andy: Indoor aerials aren't expected to work well for digital reception. There's just too much attenuation - the signal doesn't travel well through walls, and below roof level, it generally has to travel through neighbouring buildings as well as your own walls. As you're very close to the transmitter, it may work well enough some of the time, but not all the time.
Still, you might as well wait a couple of weeks and see what happens when the power is turned up on the other multiplexes.
Different boxes do have different sensitivity, so sometimes one box will see more channels than another when signals are marginal. If the signals are at this sort of level, you'll probably find that channels are unreliable, constantly breaking up.
For best results it's normally recommended to use a roof-top aerial, with enough clear space around it to avoid reflections from metalwork and other hard surfaces. Using a similar aerial in the loft is next-best, but still usually leads to less good results. Indoor aerials usually pay more attention to aesthetics - what it looks like - and less to the actual functioning of the device.
You're close enough to the transmitter that if you do get an outdoor aerial, it should be a really small one! It might even be necessary to add attenuation to keep the levels below the point where they would overload the tuner.
Justin Smith of AerialsAndTV.com has spent a fair bit of time researching the performance of the aerials he sells. If you do want to stick with an indoor aerial, or have no choice, it might be worth looking at his site: Online TV FM DAB Aerial sales (RG47SH)
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Menna: check for a loose, disconnected or broken cable, because you should be getting perfect reception. Also, if you retuned before 6am on Wednesday, retune again - all services were off-air at that time.
If you didn't retune at all on Wednesday, you would have lost BBC channels but should still have all the others.
Some boxes auto-retune every night and could have been confused when the services were off air.
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notts13: This is because a new transmitting aerial has been installed at the Dover transmitter, which directs more signal where it's needed into Kent, and less across the channel into France where it could interfere with their own digital transmissions.
Your best option is to go with satellite. Buy a Freesat box over here and have a satellite dish installed to point at the Astra 2/Eurobird cluster of satellites at 28.2/28.5°E. French-language transmissions come from a different cluster of satellites, so you would need a local installer who know what they're doing.
The aerial work is done long before the actual switch-off of analogue transmissions - there simply isn't enough time to replace the aerial and transmitters in one night.
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Saturday 2 April 2011 4:20PM
Jim: Go to Find out how to receive Freeview and Freeview HD | ukfree.tv - independent free digital TV advice and click 'By Direction'. That shows the bearing as 102°, slightly south of east.
A compass will not quite show the right bearing because these bearings are east of true north, while the compass needle points to magnetic north, a few degrees different. However, the aerial has a relatively wide cone of acceptance so it doesn't have to be that accurate - just adjust the aerial for best results. (RG47SH)