We have had continual regular interference on freeview. Key factors -
- Always - a strip from top to bottom of the screen about 20% of the screen width - where there is continuous pixel activity blocking out the image. The rest of the screen is fine and shows image. However sometimes the band broadens to up to 40% of the screen.
- During interference it can sometimes stop for a minute or two and then restarts
- usually happens at weekends after mid morning
- or mid to late evening on any day
- TV can run fine for an hour or more and then the interference starts.
- some days we have no problem
There is no mobile phone or other home based signal that could cause this as far as I can determine since our house is about 150 - 200 yards from any other home and I have shut down internet and mobile phones to try to isolate the cause.
I must suspect possible transmission interference from outbound signals - it is almost like "radio ham" interference of old.
John Couch: We dont have a postcode, which might help.
Single source interference is the most likely cause - water heaters etc? Mobiles wouldn't cause a problem, but the power supply to a DEC phone might. Its generally the timer or power supply which causes interference.
There is one other thing. If your using a digibox attached to a TV, then the signal is fed from the aerial socket, to the box, and then to the TV via scart. My old CRT TV has various scarts/RCA's into a scart switcher, including the DVD player, and the PVR runs via a decent quality set of RCA's. However, I get interference on the DVD (dark ghosting bands across the screen) and sometimes the PVR as well. The scart switcher and most of the cables into it are not well shielded (and a dodgy scart imput into the TV means I'm not touching the cable), and this leads to interference. A better scart cable or aerial lead might help.
Of course the other thing could be the TV itself...
John Couch: Although the fact of your home being relatively isolated from your nearest neighbour is inclined to eliminate the possibility of the interference entering your receiver via the aerial, therefore it could be caused by mains borne interference, something which you can check out with the aid of a small AM / FM portable radio using the following procedure.
Although portable radio's with an LW facility are better for this type of test, however medium wave or VHF FM types can still be used. The procedure being to tune the radio to the top end of the band where no transmissions take place followed by turning up the volume until background noise is heard, finally positioning the radio close to a socket near to the incoming mains, as should any interference be entering your household via the mains, its presence will be known about by a loud ripping type noise coming through the radio.
By the way, if using an FM radio, make sure that you fully extend its telescopic aerial.
This may help a bit:
Post code is BD16 1UH
Water - central heating which is always on
DEC - we do use a number of wireless phones through the house and have for many years. The nearest unit is about 20 ft away (living on its battery) and the main phone power supply is two rooms away from the TV
We don't use a digibox, the TV (Toshiba) has its own inbuilt freeview . The signal is run from an external multi-feed aerial direct to the TV via plug in connector.
We have no other kit connected to or near the TV since we use it the kitchen.
We had no problem for several years and then this all started
I suspect it is not mains driven since it is occasional, sporadic, and mainly at week ends or the evening. If mains induced I would have expected it to happen soon after switch on and regularly. Nevertheless, will check because anything will help.
John Couch: Remember that the kitchen usually has more electrical stuff than almost any other room in the house - washing machines, boilers, microwaves, freezers, etc.
Of course it might be more than just one thing. If your TV's feed has started to develop a fault (frayed cable, etc), then that combined with a source of interference which wasn't a problem before might be enough to bring on the problem. You can check if the TV is at fault by putting it on another feed - if the TV in the main room is fine, then connect the kitchen one to that feed for a while - if there is a problem, then you know its the TV. If not, then its the system/external interference.
If you have one of those cable indicators that use for DIY, try seeing whats live etc around where the feed is - you'd be surprised whats in your wall sometimes!
And there is nothing to be lost by getting another aerial lead - they are really cheap, even for a decent shielded one, and that might stop the problem. I'd certainly follow JB38's advice and use a radio to try and see what interference there might be, and keep a diary of when the problem happens - its often the little things which cause the problem, and if you can find out where the problem lies and when, you can generally deal with it.
John Couch: In addition to all said, there is another aspect of the problem that I omitted to mention, insomuch, does the interference affect the audio in any way?
Also, there is another test that I would like you to carry out "during" the next spell of interference, that being to press the menu button and see if the interference is still evident or not, because if it is still there, then that's inclined to point to the problem being caused by an internal fault on the TV rather than anything picked up by the tuner, as selecting menu takes the tuner out of the equation.