Completely missing ITV stuff on freeview

[kalniel]

I'm in an area that supposedly has no plans to go digital until analogue gets switched off. However, I borrowed a mates box and found that I actually get 75 channels pretty much crystal clear - signal quality almost always above 80% for each channel.

But for some reason I don't get any ITV channels.

Is this actually lack of signal? And if so, why do I get such good signal for everything else? Or is it something wrong with the set top box, which is a sagem itd60, like it's unable to process whatever frequency ITV happens to be using?

I wanted to try out some units from Argos but annoyingly they exclude them from the 16day money back thing, even though it's not for hygine or personal security reasons :/

Cheers,

[johnny02004976]

mate i had exactly the same problem the other day, i found that i hadnt connected a cable from the set top box to my TV ( i had a scart from box to TV, and a cable from roof aerial to box)

once the cable was in i rescanned and ITV appeared

in regards to argos mate - if the set is deemed to be faulty then they will replace it for you, you just cant take it back becuase u dont like it

[kalniel]

I physically can't connect any more things I've got scart and RF out going from the box to the TV, and RF in from a communal rooftop aerial to the box. That's all the connectors it's got (so that you can still watch TV when the box is off).

Yeah I know about the faulty thing, just annoyed that most other things you can take back if you don't like them, but they've obviously had too many people 'try out' freeview boxes

[johnny02004976]

yeh mate you'd be suprised i was customer service supervisor for about 9 months there and the things people do are crazy. especially round christmas time you'd find people buying them to make the most of the extra channels over xmas then bring them back saying they dont want them..its the same with digital camera's, people would buy them, use them on holiday and then return them.

do you have another box u can test it with??

[Funkstar]

have you tried re-scanning a couple of times?

My Freeview SCART dongle (mini box that plugs directly into your scart socket) kept missing a Mux when i first installed it, after a couple of re-scans, everything was picked up correctly.

Of course your area might just not have all the Multiplexes available. See here for a list of the DTV chanels on each mux:
http://www.digitalspy.co.uk/terrestrial/mux/

A Mux (or Multiplex) occupies the UHF frequency for a single analogue channel.

[BigBry]

This site also provides some useful info;

http://www.dtg.org.uk/retailer/coverage.html

[chrestomanci]

Sounds like you are not receiving one of the Multiplexes; perhaps your TV antenna is a bit wonky or tuned to only receive signals on certain frequencies.

On digital TV, several TV channels (usually 4-6) are multiplexed onto each frequency; the channels that are muxed together are usually from the same or related companies. As I recall, there are 6 multiplexes, the BBC has 2, Commercial freeview broadcasters have 3, and the one remainder is reserved for Top up TV subscription services.

Anyway digital terrestrial TV transmissions share the same band as analogue, but because analogue got there first, their channels are near the centre of the band, leaving freeview transmissions at either end. In different areas the analogue transmissions are clustered in different parts of the band, so that houses can be fitted with narrow band antennas that are best at collecting signals in that part of the band, and don’t receive signals from neighbouring areas which cluster their analogue signals in another part of the band.

Consider this ASCI art diagram:

22 ------------------------------ 68
    A A  AA  A       a  a aa a
----^^^^^^^^^^^-----

The top row is the UHF channel numbers from 22 to 68.

The next row shows where the five analogue terrestrial TV stations in your area as upper case ‘A’s. They are clustered at the low end of the band. The lower case ‘a’s are the transmissions in a neighbouring area that are clustered nearer the high end of the band

The bottom row shows the sensitivity of your TV antenna. Because in your area analogue transmissions are in the low end of the band, the person who installed your antenna used one that was tuned to low band transmissions, and is not sensitive to high band ones.

Now let’s add some digital TV to the mix:

22 ------------------------------ 68
D DA A  AA  A D D D a  a aa a  D
----^^^^^^^^^^^-----

As you can see, your antenna should be able to pick up the first five multiplexes quite easily as they are in the part of the band that it is tuned to, but the top one around channel 60 will not be received.

[Legin76]

Have you thought about trying a booster?

[kalniel]

Thanks for the replies

do you have another box u can test it with??

Nope.. that was why I was musing about Argos

have you tried re-scanning a couple of times?

My Freeview SCART dongle (mini box that plugs directly into your scart socket) kept missing a Mux when i first installed it, after a couple of re-scans, everything was picked up correctly.

Of course your area might just not have all the Multiplexes available. See here for a list of the DTV chanels on each mux:
http://www.digitalspy.co.uk/terrestrial/mux/

A Mux (or Multiplex) occupies the UHF frequency for a single analogue channel.

That explains it perfectly - I'm not seeing anything from multiplex 2. I'll keep trying to rescan under different weather conditions

As you can see, your antenna should be able to pick up the first five multiplexes quite easily as they are in the part of the band that it is tuned to, but the top one around channel 60 will not be received.

Good call, but nothing I can do about it as the arial is the property of the flats management - any chance a portable aerial will give good results?

Have you thought about trying a booster?

I think the box has a booster built in, but otherwise no - I'm not sure it would do anything as it's literally like the channels aren't there at all - it's not like I'm just getting a weak signal.

Hmm.. though I note signal boosters *are* covered by the 16 day guarentee.. could be worth a try

[chrestomanci]

Good call, but nothing I can do about it as the arial is the property of the flats management - any chance a portable aerial will give good results?

Only if you live close to the transmiter, and in that case I would expect the building's antena to manage even it it is optimised for a different part of the band.

As you share an antena with your neighbours, have you asked them what their reception is like?