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Will Freeview Pictures Be More Stable When Analogue TV Is Switched Off?
All of our Freeview boxes, and all of our Freeview-integrated DVD recorders suffer, to a greater or lesser extent, with the picture freezing momentarily whenever certain light-switches are turned on and off in the house.
I understand that once the Analogue TV signal is switched off, the Freeview signal's gain is then going to be lifted, for improved Freeview picture and sound stability, and, maybe, other improvements with the reception, etc.
Does anybody think that once my London region's Analogue TV signal is switched off, in April, and the Freeview signal's gain is then able to be lifted higher than it is now, my Freeview boxes/integrated Freeview DVD recorders are going to be more immune, or even completely immune, from these momentary picture freezes whenever somebody in the house switches a light-switch on, and for some reason, particularly whenever somebody switches a light-switch off?
I've heard that this particular phenomenon with Freeview is caused by Radio Frequency Interference (RFI). I am already using a Tacima Mains Extension Lead with built-in RFI suppression for some of my Freeview equipment, but it does not really help. If the picture freezing is being caused by RFI, will the Freeview signal's gain being lifted help to immunise RFI from spoiling my Freeview pictures?
I understand that once the Analogue TV signal is switched off, the Freeview signal's gain is then going to be lifted, for improved Freeview picture and sound stability, and, maybe, other improvements with the reception, etc.
Does anybody think that once my London region's Analogue TV signal is switched off, in April, and the Freeview signal's gain is then able to be lifted higher than it is now, my Freeview boxes/integrated Freeview DVD recorders are going to be more immune, or even completely immune, from these momentary picture freezes whenever somebody in the house switches a light-switch on, and for some reason, particularly whenever somebody switches a light-switch off?
I've heard that this particular phenomenon with Freeview is caused by Radio Frequency Interference (RFI). I am already using a Tacima Mains Extension Lead with built-in RFI suppression for some of my Freeview equipment, but it does not really help. If the picture freezing is being caused by RFI, will the Freeview signal's gain being lifted help to immunise RFI from spoiling my Freeview pictures?
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Are these simple on/off light switches or dimmers? The latter could be a cause of stray interference. Also what kind of bulbs? A failing starter in a fluorescent strip is also a suspect.
Any of the above could allow noise to get into the TV through the aerial cable when light switches are turned on or off. The fact that your mains filter isn't helping suggests that it is not coming through the mains wiring.
I think we're going from something like 20Kw to 200Kw after DSO, which should hopefully sort things out.
At the moment though we predominantly use satellite as it offers the best picture quality without the annoying break-ups.
Those are indeed the figures for the main muxes at Crystal Palace - the HD mux will increase from 10Kw to the same 200Kw. That lower power is the reason some people have problems getting the HD channels when the SD channels are received perfectly.
The "8K" mode which replaces "2K" at switch over seems to make the signal more prone to electrical interference dispite the increase in digital output power from the transmitter.(The broadcasters say it should be less prone).
Also when it gets windy in my location I momentary loose the digital signal due to next doors conifers. This never happened in "2K" mode. Looking on the digital receiver,the signal strength stays in the green but the signal quality goes into the red. I am only 6 miles away from Winter Hill.
I have another aerial with a clear path to North Wales and switch over to Moel-Y-Parc transmitter on windy days.
They are simple on/off light-switches. The worst one to cause momentary picture freezing in the whole house, for me, when I am using one of my Freeview-integrated Panasonic DVD recorders (DMR-EX85 and DMR-EH60D) is the bathroom light-switch. The bathroom is immediately underneath my room, one floor down. Whenever somebody turns "OFF" this switch, I'd say about 80-90% of the time, my Freeview picture freezes momentarily.
If I am making a recording, I hate these glitches to be ever-present in the recordings, so, if it is a particularly important programme, which I want to record, that's about to start on one of the Freeview channels, in the evenings, after dark, I 'plead' with people to use the bathroom just before the programme starts, otherwise please do your business in the dark, until my programme finishes !!!!!!
The bulb is just a regular 40 Watt, bayonet-type.
The aerial cable is getting on a bit, and I know that it is not the absolute highest quality cable available, so, if there is no change after the point in time when I know that the Freeview signal's gain has been lifted, I may replace all of my aerial cabling, although this would be a very big job to do.
I would ensure that the fly lead was good ... if nothing else.. some of them have next to no screening at all - letting in everything from wifi to DECT to a dodgy light switch..
There are many situations where getting a good aerial(with balun)
and screened down lead puts the signal well back from the digital Cliff
adn I hope Gomez was Not joking - there are great issue with higher power adjacent or close channel signal - a concern with the selling off of 800MHz band.
That is very good to know, and I keep my fingers crossed that it will be the same here. As you, and others have pointed out, after a region's DSO, the gain increase of the Freeview signal should be something like a maximum of 10x the pre-DSO level, which sounds substantial, but, obviously, I cannot tell if it sorts things out until after DSO happens in my region.
Do you know if the problems you had before DSO were due to people switching light-switches on and off, central heating etc, or do you remember it just being, seemingly, random blips?
I'm 22 miles from WH and have never had any freezing or blipping problems before or after DSO. I have also never had interference from domestic equipment, nor yet from mopeds, lawnmowers, strimmers etc. I'm not trying to be smug, but having read about others suffering these problems, I do wonder if the purpose-built flat I live in is a natural Faraday cage.
Mike.
The interference is probably getting in via poor quality aerial cable and/or unscreened wall sockets. Even if the power at the transmitter is increased what arrives at your aerial is a small signal. Local electrical interference will still swamp it.
See Bill Wright's comparison between good and poor quality cable at http://www.wrightsaerials.tv/articles/coax-cable-quality.shtml. The use of satellite quality cable that is 100% screened will make a difference if switching on and off appliance in your own household is causing problems. If you have aerial wall sockets make sure that they are also 100% screened. See http://www.satcure.com/tech/wallplates.htm for information on screened and unscreened wall sockets.
If you are using an aerial splitter be aware that some are totally unscreened. http://www.admac.myzen.co.uk/Splitter/
If your mains extension works at all in reducing interference it will only stop it getting in to the mains side of your box or TV. It will not stop it getting into the aerial lead/flylead/wall socket. Remember that your mains wiring throughout your house is acting as a large aerial for the household generated interference.
If you aerial is mounted in your loft it could be/will be also picking up any interference from nearby mains wires carrying the lighting circuits.
Where I used to live, I had a 1970s indoor aerial sitting on my windowsill. Every time the boiler clicked into life, the picture would gain a line of blocks and - often - I'd get a very loud noise from the speaker (made me jump every time). This was in 2002, before Freeview launched, and all the muxes were low power 64QAM. After half the muxes changed to 16QAM (and I think there were power increases as well, over all muxes) the problem was much rarer. I've moved since then, and now the aerial isn't effectively in the same room as the boiler, I have not seen the problem at all.
I would definitely recommend shielding cabling (or not using an indoor aerial) rather than assuming the problem will go away with DSO. Any local impulse interference could easily knock out the signal, even at higher powers - especially with less robust modes, and the reduced error correction on the commercial muxes.
My parents live a little bit nearer to Winter Hill than you - on the old 1970s aerial (with rubbish Five picture) there used to be regular glitching in my bedroom caused by the boiler clicking on and off (noticeable on the Moel-Y-Parc signals and Five as horizontal lines, and Freeview as green blocks) - once the aerial was replaced with a better one (giving a perfectly watchable if a tad grainy Five picture) they didn't glitch again.
The post DSO signal boosts the signal enough to take it far enough from the noise floor to mean that local interference doesn't wipe it out - imagine being in a pub with music playing - pre-DSO it's like listening to a mate who can't speak too loud as he has a sore throat so a fair bit of what he is saying is lost under the background music. Post DSO he is able to shout and you can hear every word clearly.
Indeed ' gomezz ' was not joking about deafening the receiver . .
To give you an idea, here the vision carrier (strongest) for ITV analogue from CP sits at 11.1mV at the receiver I/P! Where as the DVB-T2 HD MUX is a mere 77.6uV (average). Mind you, both are received perfectly in my case.
It's a bit like someone shining a bright torch in your face at night while your trying to see a distant dim object.
Errr Um
11.1mV is 71.1uV .
77.6uV is a very strong digital signal , but to be expected with line of sight after DSO ,due to the very large increase in transmitted power.
The best thing that could have been done but a little late now is for all the DVB-T and DVB-T2 broadcasts to have a one channel gap in between.
This would then allow a big increase in the performance of TV tuners.
Also I was having a discussion with a engineer who designed tuners and he told me that tracking filters are not used on the front end of the current generation of tuners.
I do not know if this is true or not of all tuners , but if it is this would severely compromise the ability of a tuner to cope with a multitude of signals coming in at different levels.
Seems technology is going backwards with regards to tuners?
Thanks for going into detail for me about possible causes, and remedies to my Freeview picture-freezing issues.
I will look into everything you have said here. The aerial is on the roof, not in the loft. It was put up years ago, purely for the Analogue TV signal.
In addition to the possible causes you have outlined, I don't know if upgrading to a better quality aerial would also help. When the makers of aerials say things like "Digital-compatible", is this just spiel? Is there such thing as a "Digital" TV aerial, as such? I'm not convinced, and I think that it is purely a marketing strategy. I've heard that if you already have a good quality aerial, put up in the days of Analogue-only TV signals, there is no need to change over to one which states "Digital-compatible", if it is of good quality in the first place, and that it's simply so they can sell another aerial to you.
11.1dBmV is 71.1dBuV.
Well, I believe it has been stated by a few members of this forum that so-called "digital" aerials usually have some minor modifications to cope with just this type of thing, though it's by no means a standard (as you said, it's mostly just marketing spiel), so you can never guarantee it - but if your aerial is a rooftop one, it's much more likely that the interference is picked up in the wiring rather than the aerial, so changing the aerial will achieve nothing. In general, the whole digital aerial thing is a scam as there are only a few places where it can make things better - also, quite often these aerials are wideband which makes them suitable to work all around the country but has the big downside of being less good at picking up signal. I would wait for switchover if I were you, and if there's still a problem, look at the options then. But I don't think you'll need to replace your aerial.
Thanks for your comments. As you indicate, I think the sensible thing to do is to assess the situation after DSO in the London region, and see if the higher gain of the Freeview signal has made anything any better. Any upheaval of the existing aerial cabling and/or mains wiring system would be a huge job.
My own experience of a strong signal, adjacent to a weak one, bears out what you say.
When receiving Waltham on UHF61 which is quite weak here in Lincoln, next to very strong Belmont on UHF60, (now with increased power), shows up this phenomenon very well.
I have various STBs of different ages and manufacturers, the newest one being a Humax HD FOX T2.
However, the only receiver that can resolve the weak Waltham signal on UHF61, adjacent to strong Belmont on UHF60, is my oldest STB, a Humax F2 FOX-T, (c 2003). This has been an excellent box for indicating marginal signals, with my DX hobby.
All the other STBs I have (including the new Humax HD box), seem equally capable of resolving weak signals, as long as they're not adjacent to strong signals.
Chris.
My guess: either the trees have grown, or your aerial and/or downlead have got worst, or your STB doesn't like 8k - or something is being overloaded by the higher signal levels. Do you use an aerial amplifier somewhere that you've forgotten about?
Cheers,
David.