All posts by Michael Perry
Below are all of Michael Perry's postings, with the most recent are at the bottom of the page.
To all:
One clue as to whether there are inversion effects is to look at how foggy it is. It is often the case, but not quite always, that foggy indicates warmer air is above cooler air, which is a temperature inversion. With that happening RF signals can travel much further than normal and cause unusual reception (some see French TV stations!) or such interference as to swamp the wanted Freeview signals. This is nothing new and has been known about by TV service engineers for many years, at least from the start of UHF transmission in the mid 1960s.
My advice is do nothing and be patient, waiting to the weather conditions to change for the better. Do not try retuning either as you are likely to lose even more programmes!
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Dave Lindsay:
Yes and that is why so many have retuned unnecessarily and lost more channels than just the ones initially giving problems. Non-technical people will follow that advice even when they should not.
The advice given above the entry box is very general and does not allow for inversions, etc. My many years experience in the TV industry (going back to 1960) tells me that when viewers think there equipment has a problem, they try to correct it themselves and often cause greater problems. Or they assume the source has a fault and blame the broadcasters for natural phenomena. That is the problem with 'general' approaches rather than specific.
The real key is to have patience first. With a satellite system, you can get a reported signal loss when it is actually a decryption problem - the on-screen message covers a whole host of situations almost all of which have nothing to do with actual loss of signals (note that my brother worked for one of the companies who supply Sky with software for the boxes). With terrestrial, there are all the effects we've seen for years on UHF transmissions but somehow people think digital terrestrial works differently when it is just a UHF carrier modulated differently, so is just as susceptible to interference and is usually reported by the box as being loss of signal when it isn't.
I would suggest that Briantist rewords the advice so that people don't jump to conclusions too fast - as some seem to if you read their submissions (as I know you do).
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Gary:
Often landlords decide to fit communal aerial systems to prevent a plethora of roof-mounted aerials becoming unsightly. But the systems have their drawbacks, especially as most of them have filters to only allow 'wanted' channels through but when new services are started they need adjustment. So I think you are wise to have had your own loft-mounted aerial as it cannot be 'unsightly' form outside the building, unlike the communal system you describe. The actual location and height of the aerial rather depends on the relative locations of the transmitter aerial and the receiving site, higher is not always better in my long experience. The transmitting and receiving aerials can be at very different heights (I used to live in Nottinghamshire just a few mile from the Waltham transmitter, that was over 200 feet higher than my house but reception was perfect as my aerial pointed directly at the Waltham aerial array).
There was, and still is, a lot of hysteria and hype about digital television, ongoing since before the switch over started in 2008. Many firms tried to 'make a killing' by saying you needed a 'digital aerial' when almost everyone who already had a UHF TV aerial that was giving good reception could continue to use that until OfCom started moving things around. The 'old' analogue services were carefully planned to make best use of the UHF Bands 4 and 5 spectrum with nil, or at worst, interference. However, since they started moving channels around there has been a significant increase in reception problems, some due to increased interference between adjacent signals and some from shared frequencies (adjacent or co-channel interference can disrupt digital more than analogue). Plus some people have found their existing aerial that worked fine until this year's retunes is no longer giving the results they expect so they have to have the aerial changed for one of a different grouping, just because Ofcom wanted the signals moved to other frequencies. That is likely to happen again around 2018 as there is an idea to add further mobile coverage possibly using existing UHF TV frequencies, so more retuning!
So, I would suggest keeping your own 'hidden' aerial as long as it is giving good reception.
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G maclean:
It could be that the solar panels are interfering with the reception of radio signals. The panels are electrical devices so contain conducting elements that may well disrupt what was previously good reception. As the panels are on your roof and fairly near to the receiving aerial the solution could be to have the aerial moved as far away from the solar panels as is feasible - or have the panels removed!
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Dave Oliver et al:
It has been clear;ly stated today (17th December 2013) that FM and AM will *not* be switched off in the foreseeable future as there are far too few users of DAB systems and far too may users of AM/FM. It has been estimated that there are more than 100m AM and/or FM receivers in use and that the vast majority of cars being used do not have access to DAB equipment. Some estimates state that a car can be converted to DAB for around £100 but when I enquired the radio unit itself would cost at least that plus there is a need for at least 3 separate aerials to be fitted somewhere on the car (easy if fitted during manufacture but hard and very expensive as an 'after-market' fitment).
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The ones who decide how the money is spent are not Arqiva not the BBC. In this instance it seems the government (DCMS) are the ones traking the decision.
So we await their further announcements together with any factual information gathered rather than anything suggested by reporters in the media whoi so often mis-interpret what is said.
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To All:
Please note that pixelation can only happen on digital TV signals so can only occur after the switchover from analogue to digital transmission. In most areas that happened between 2008 to 2011, with a few slightly later. So if you have had good reception and display of TV programmes since then but recently been having pixelation then it is not because of any 'switchover' but there can be a host of other reasons for reception difficulties.
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Michael
I am saying that analogue cannot and does not suffer from pixelation - that is a purely digital artifact. So Freeview, FreeSat and Sky can all potentially suffer from pixelation as they are digital transmissions. Before switch over, all terrestrial transmissions were in analogue format so could not have pixelation, but they did suffer from co-channel and adjacent channel interference when high pressure systems caused signals to travel further than normal- as it does also with digital transmissions as some have reported here. Sky have been digital for longer than terrestrial transmissions have.
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Kevin Gardener:
With regard to why many people who may have access to HD services don''t actually use them is a matter of audience/viewer inertia. Most non-specialist viewers are only interested in the programme *content* and are not concerned about how that content is delivered. As the vast majority of viewers what entertainment in its several forms they do not want to be bothered with whether it is available in SD or HD - just that it is as enjoyable as they expect. How that enjoyment is delivered is mainly of interest to technofiles, but the broadcasters (BBC, ITV, Sky, etc) keep on about also being on HD that some don't even care as they can enjoy it on the programme they are currently watching even if that is not an HD service!
To try to encourage the non-technical viewer to watch in HD when it is available (not all programmes are made in HD) the providers like Sky and Freeview try to get the receivers to display the HD version in the most advantageous position, so BBC1 (for example) is on Sky 101 and Freeview 101 and that may be in SD if the receiving equipment is not HD capable (or the Sky subscription does not include the HD premium) or it is in HD if that is available.
So figures about how many viewed in SD or HD are often misleading as rthey fail to take account of viewer inertia and preference. .
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Friday 13 December 2013 8:38PM
Music Monster:
See my response above. The conditions can cause such interference that signals appear to be being lost. Do *not* retune.