Missing Hd Channels

[goodgoalie]

Today I have suddenly lost about half of my HD channels, including BBC4 and BBC News. The channel list now goes from 105 straight to 201. Have retuned twice but still the same. Anyone else had similar problems?

[Guilbert53]

This help?

https://www.freeview.co.uk/tvchanges#FJ5KHIDRdv2yEaor.97

[goodgoalie]

Thanks for that. Dismayed to see: "in some cases you may need to change your aerial to continue receiving these channels". Absolutely typical! I'm sure I read a few years ago that the powers that be were going to sell off certain TV frequencies to the mobile phone network - I wouldn't be surprised if that is what has happened. Really, really annoying!

[hellywelly4]

I had something similar when the Freeview channels were updated in my area a few weeks ago. The advice was to re-tune the tv. As I have a Humax box it didn't work, but I got help to re-tune my Humax box and it was fine. Don't think you'll need a new aerial, she said hopefully!

[Buenchico]

The frequency reallocations have come about as part of a Europe-wide agreement (because radio waves don't stop at national borders). They were needed to make room for the vast number of new services which constantly have to be squeezed into the radio frequency spectrum. They're part of the same agreement which will see FM radio broadcasting come to an end in a few years time.

A TV aerial should, ideally, have elements which are exactly the right length to 'resonate' with the frequency which is to be received. Since TV channels are transmitted in 'bundles', called 'multiplexes', with each multiplex using a different frequency, you should theoretically have a different aerial on your roof for each multiplex. (So you'd need about 10 aerials on your roof to receive all of the multiplexes for the main channels). That's clearly not possible, so any aerial will only be a 'rough match' to the incoming frequencies, so it will be better at receiving some multiplexes than others.

Matters are in fact even worse than that because, unless you've had a new aerial fitted since the digital changeover, the aerial on your roof was never designed to resonate with any of the current frequencies (because analogue TV was transmitted in a completely different frequency range). So what most homes have currently got on their roofs are aerials that are little better at doing the job properly than the wire coat hangers that people used to use for car radio aerials. (The digital changeover was based around the assumption that approximately one third of households would need to have new aerials fitted. It turned out that far fewer homes needed new aerials but it did then leave lots of homes in the 'wire coat hanger' situation, so it's hardly surprising when some of them can't get reliable Freeview reception).

Your aerial clearly doesn't resonate well with the frequencies now used by the 'COM7' and 'COM8' multiplexes. Buy a signal booster from Argos:
http://www.argos.co.uk/product/5713543
(You'll also need a fly lead. They're widely available in discount stores, etc or you can get one cheaply from Screwfix: https://www.screwfix.com/p/fly-lead-coaxial-plug-to-plug-1m/41720 ). Install the booster and carry out a further retune. (NB: If you're given the choice between 'adding' channels or 'replacing' them, ensure that you use the 'replace' one; you need to force your TV to start the tuning process from new).

[goodgoalie]

Many thanks for that, Chris. At about 6pm tonight I did a fUrther Autotune, and - hey presto - the missing channels have mysteriously reappeared! No idea what's going on...
Funnily enough, my aerial (which I inherited when I moved here over 10 years ago, so I have no idea how old it is) isn't even on the roof - it's just attached to a post in my loft. The picture has always been great, and since this latest retune, seems better than ever. Very curious.

[Buenchico]

I'm glad you've got your channels back but you might still lose them again at a later date.

That's because the strengths of the signals at your aerial don't remain constant. They're affected by lots of factors, such as the 11-year sunspot cycle, individual solar flares, atmospheric pressure, precipitation, the length of the day (which affects the height of the ionosphere), interference from other radio transmissions, interference from devices in your home (and in your neighbour's homes), such as computers, printers, etc, and much more.

So your aerial can clearly cope when signal strengths are good but it struggles to 'pull in' certain frequencies when they're not. If you do experience further problems a trip to Argos (to buy a signal booster) should solve them.

[bhg481]

Following Buenchico's comprehensive reply and your statement that it's a loft aerial, has the snow melted from your roof since your first retune and the latest one?

[goodgoalie]

Hi bhg. In spite of all the bad weather, there's not really been snow lying on the roof - too windy, and it was all blown off into drifts. Just glad to have the channels back (watch BBC4 a lot, so like it in HD), but how long they'll all be there for, who knows.......