Missing Freeview Channels.

[sad old git]

I noticed recently that a couple of freeview channels have gone missing ( can't spell disappeared) the main two being movie mix on channel 32 and pick tv on channel 11. Anyone know why this is so?

[Buenchico]

Digital TV channels are broadcast in 'multiplexes', which are simply 'bundles of channels' which share the same frequency. In an ideal world the elements of your TV aerial should be exactly the right length to 'resonate' with the frequency which is to be received. That would mean having a different aerial for each multiplex, so every roof would be covered in aerials. Clearly that's not realistic, so we use aerials which are only a 'rough match' to the different frequencies that they're required to receive. Consequently each aerial is better matched to some multiplexes than to others. Your aerial seems to be poorly matched to the frequency used by the multiplex which carries Movie Mix and Pick TV.

The strength of incoming signals at your aerial doesn't remain constant. It's affected by the 11-year sunspot cycle, individual solar flares, the length of a day, atmospheric pressure, precipitation, interference from electrical equipment in your home (and those of neighbours) and lots of other factors. Your aerial can provide a good enough signal for your TV (or set-top box) when conditions are good but struggles (and loses one of the multiplexes) when they're poorer.

In the first instance, try simply retuning your TV (or set-top box). If you're offered the option to 'add' channels or to 'replace' them, choose 'replace'. (That wipes the slate clean and starts again). However, in order to prevent the problem from reoccurring, it's likely that you'll need to boost the signal strength from your aerial with one of these:
http://www.maplin.co.uk/p/1-way-aerial-amplifier-rt67x
Larger supermarket branches (such as Tesco Extra and Asda) sell them cheaper but the model I've linked to is the best available as it offers exceptionally high 'gain'. (NB: If you install an aerial amplifier you might still need to retune your TV/box before the missing channels reappear).

[murraymints]

I have to trashcan most mornings for these channels ...I switch off plug on wall at night and they go....but come back after retune

[murraymints]

Rescan...predictive thingy wants to ditch them !