All posts by Michael Perry
Below are all of Michael Perry's postings, with the most recent are at the bottom of the page.
Steve P
It's not the different modulation but the different compression and encryption methods together with error correction algorithms that makes the difference. With 'old' analogue TV, vision had AM and sound was FM with no attempt at compression, etc. That, as we all should know, suffered from co-channel as well as adjacent channel problems together with the effects of tropospheric lift giving unexpectedly long transmission distances.
With digital signals, there are several modulation methods but the more recent systems use 64QAM or even 128QAM. The digitised signals are also compressed and have error correction codes inserted. And they still suffer from the effects of co-channel and adjacent channel, but usually to a lesser extent for adjacent, 3rd and 5th channel separations. It is because of these different formats, though they are still a form of 'FM', that digital signals tend to fare better when interference is around - but correction can suddenly fail to sort out the incoming wanted and unwanted signals and all the affected ones become undecodable, as has been reported by many on these pages.
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John Pilkington:
Interesting. Worth noting the wayb they responded talks about the signal 'leaving our Transmission centre' - which is nothing to do with the Waltham transmitter, nor any other. The transmitters are not operated by ITV but a separate business and it is they who control how the transmitter works and is set up.
That all suggests there was a problem with how it was set, your email prompted ITV to contact their transmission contractor who probably corrected what had been set wrongly (at least I suspect so) and hence the problem is resolved. Not by ITV but I suggest you were instrumental in making it happen. Well done and I'm sure several viewers in the East Midlands are now a lot happier. (I used to live in the Vale of Belvoir [pronounced like beaver] and worked in Nottinghamshire, Leicestershire, Derbyshire and parts of South Yourkshire fo some years.).
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Paul:
See Tropospheric DX Modes for a discussion on Tropospheric Ducting and what causes it. It's a bit technical but worth wading though.
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JC:
There's no such thing as a 'digital' aerial, see the BBC website for a discussion about UHF aerials and elsewhere on this site. Try BBC - Help receiving TV and radio - aerials for digital terrestrial TV or http://www.bbc.co.uk/rece….pdf for useful information.
A good UHF aerial of either Yagi, modified Yagi or wideband design will be suitable for any DTV reception. The nature of the modulation content has NO effect on the transmission, propagation and reception of the carrier signal. It is the reception aspect that is done by the aerial. The decoding of the signal is done by the television or STB.
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To all those experiencing problems with Sony equipment, it appears to be a faulty software update causing problems. There are many entries in other parts of this website all saying the same thing on a number of different transmitters. That shows it is not the transmitter at fault and as it appears to only be affecting Sony equipment and no other manufacturer's products we can safely assume it is unique to the Sony update which I gather was sent out Friday evening.
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If, as has been suggested, the v1.70 software has been available since 2010 and only Sony equipment seems to be being affected, why was the reported change in EPG coding not tested properly? And why have no Pioneer owners reported the problem if they are identical? And why is it affecting users with the 1.65 version as well?
It is clearly not specific to one transmitter as the range of comments here, and on the BBC Technology website, are from widely differing areas but there is one common factor - Sony. The EPG coding may have been changed but it has not apparently affected any other makes - as far as we know.
Sony say, at last, that they are looking into it. I suspect their support phones will be red hot Monday morning. But if it's due to a change by Arqiva, why have Arqiva been so quiet?
I await clarification and developments from both organisations. It really is very poor for customer relations and is another example of poorly tested software and/or changes of coding.
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Neil:
How long ago was the restrictive covenant applied and is it still enforceable by the imposer of that covenant? (They usually have a time limit and have to be enforceable if they are meaningful. They're often applied by developers but usually cease after either 5 or 10 years.)
A satellite dish definitely has to be mounted externally and not above the ridge line - they cannot fitted inside the loft satisfactorily, so wouldn't that come under the restrictive covenant as well?
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Without wanting to 'muddy the waters' is it possible that some refering to a 'booster' in the loft actually mean a distribution unit? Something like the Labgear MSA2163 (http://www.labgear.co.uk/category/distribution-amplifiers/amplifiers/16-way-distribution-amplifier-with-bypass/1002/1014/31/) might be mistaken for an aerial amplifier wjen it's main job is to distribute the signals with minimla loss.
Just a thought.
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Anita
Many Freeview boxes use your post code to determine which of the available local news services it sets as being your main programmes and which are to be 'secondary' (in the 800's). Example, if you live south of Oxford you might well want the South Midlands news as your main feed instead of the South services (sourced from Southampton studios!).
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Tuesday 9 July 2013 4:49PM
Kevin:
The Astra satellites at 19.2 E are actually 6 separate birds in co-location orbits, meaning the appear to be in about the same place in the orbit but they are actually a few hundred metres apart. This is usually done to provide more multiplexes so more services can be broadcast. Plus each satellite has a limited power availability so there is a limit on how many transponders any single satellite can provide.
So with Sky needing more spectrum for extra services they have to use more satellites, but there is a limit to how many can be co-located so they use two close locations that can be seen with a single dish, albeit a wider one to cover a slightly wider orbital arc.
The curvature of any dish is designed so that as much of the signal falling on the dish surface is focused into the feedhorn of the LNB.