Why do I sometimes get a red dot / poor signal on [channel x]?
The red dot only applies to ITV Digital boxes and means that you have a poor signal. More modern boxes are more user-friendly and tell you that your signal strength is low. Intermittent poor signals can be the result of cars going past, lights being switched on/off, gas hobs being lit and heating systems being turned on. Basically anything that makes a spark. At a physics level a spark makes a square wave, which has an infinite bandwidth. An infinite bandwidth means that it interferes with all channels on all frequencies. One spark can break up a picture for half a second and more constant interference for longer. Using double-shielded cable such as CT100 between the aerial and the box is the best way of avoiding these problems, but sometimes there is nothing that can be done. If the weather is very bad it can affect your signal, especially in an electrical storm. If the red dot is on one multiplex then there may be interference from another device, like a video recorder or you may suf
