It is a feature of television signals that they can be effected by the weather. Aside from the obvious damaged that can be caused by wind or torrential rain, the onset of summer can cause a more intriguing problem called "inversion".
Basically, when the sun heats up the land, the hot air can get trapped below cold air at high level. This creates an "inversion layer" which acts like a polished mirror to TV signals. This causes two problems: you can receive both the original and a reflected signal from your own transmitter (on analogue TV this appears as "ghosting") or interference from TV transmitters that are normally too far distant.
So, whilst a loft-mounted aerial will provide reception at some time, it will fail at others. The only real solution is to mount the aerial (or a new Class I aerial) outside on a pole, but some people report that changing the cable from the aerial to the set-top box to the high-grade satellite cable can also help.
The SCART connection, by the way, only carries a single TV picture, not the Freeview transmission multiplexes, so if this is disconnected it will result in degradation to every channel at once.
Anne Battersby : Your just 5km from Crystal Palace...so your recpetion should be excellent. Almost certainly you have a severe problem with your aerial system, because that is very very close. In fact you may need no more than an indoor aerial.
The Freeview helpline would have suggested exactly the same thing.
Hi I cannot receive any freeviewchannels through my freeview tv or freeview box nearest transmitterCrystal Palace but your map shows area I live in Erith as poor reception( pale green ) I have a communal aerial on block of flats roof what can done if at all to improve receipt of these freeview channels? Thanks
As you live in a building with a shared communal aerial, you first step should be to check with your immediate neighbours in the block to see if they have exactly the same problem as you report. If they do then you must contact the managing agents for them to have the aerial system checked professionally. You cannot do it yourself as it is not your property.
If your neighbours do not have the problem, then it is either you equipment that has failed or esle the connections from the aerial socket on the wall to your TV, etc, Start by swapping the flylead between the wall aerial socket and the equipment, they are very cheap to buy. If that does not cure the problem you will need to test whether your TV gets the signals in a neighbour's flat with their permission. If that works then your aerial socket feed is faulty. If that doesn't work then your TV is faulty.
Its off the richter scale of annoyance because I cant/wont ask my neighbours and the landlord isn't too bothered about things like this. Taking my box to friends and family is just hassle I dont need
His aerial system looks like spaghetti junction and its probably faulty , short circuited or badly/over amplified. I doubt an attenuator will work and cant understand why its only on the PSB 3 band
His aerial is possibly misaligned but why does it receive other channels perfectly
I have been running though a checklist and its not HDMI radiation and my Coax leads are quality QED double screened. I dont unfortunately have another HD receiver to prive my Humax tuner may be faulty.
It can work for a while but generally now just loses signal rapidly flashing on and off.
Its so annoying that I may have to move. I need control of my own aerial
With a communal aerial system the only people who can deal with any problems are the owners or their managing agents. So you need to keep contacting them until they have the system properly checked by an aerial contractor. If you were to engage your own, they almost certainly refuse permission for them to access the system and will refuse to pay for it.
As you are apparently in a block of flats you cannot install, or have installed, your own aerial anywhere on the building with the permission of the building owner and you may need planning permission for an additional aerial.
Not knowing where you live, it is impossible to advise about which is the most likely transmitter for you to use. If you enter a full post code into this website you will get 6 small blue boxes below your posts containing links to useful reception information.
All I can advise otherwise is to keep talking to your landlord or their agents.