For the last week or so we have not been able to get either itv or channel 4. It either says no signal or is so fractured that it’s very difficult to watch. I went on all the relevent websites which told me to retune, but when I’ve done this both itv and channel 4 disappeared.
Is this a problem with the aerial or the receiver?
Be kind and don’t blind me too much with jargon.
Where are you? Have you had high wind recently? If so, your antenna may have shifted.
In digital terrestral TV, several channels can share the same frequency (the same multiplex or “mux”, in the jargon). That is one of the efficiencies of digital TV. ITV and Channel Four share a mux, and so if you are having problems receiving one, you will have the same problems with the other.
It may be that you are in a marginal area for the particular frequency that the ITV/C4 mux is transmitted on in your region. In spring, leaves growing back on trees makes a real difference to the strength of signal that you receive through your aerial, and in marginal areas this can lead to the symptoms you describe. Possible solutions would include getting a bigger aerial, or having your aerial serviced, because they do deteriorate. Unless you are close to the transmitter, you need a good aerial for digital TV.
If you are still using your old aerial that you used for analogue, it’s possible that if the digital mux frequencies are a long way from the analogue frequencies you may need a new aerial.
If analogue TV is due to be switched off in your region in the near future, you might be able to just wait. Digital transmissions are currently broadcast on low power to avoid interference with analogue reception - the intention is to increase the power once analogue goes away. This might solve your problems.
Failing that, try a higher aerial - nothing beats increased height for improving reception. Replacing a loft aerial with a roof aerial can also work wonders.