My ITV/C4 Freeview channels have disappeared - what can I do? Is it my SCART ca
Brian Butterworth published on UK Free TV It is a feature of television signals that they can be effected by the weather. Aside from the obvious damaged that can be caused by wind or torrential rain, the onset of summer can cause a more intriguing problem called "inversion".
Basically, when the sun heats up the land, the hot air can get trapped below cold air at high level. This creates an "inversion layer" which acts like a polished mirror to TV signals. This causes two problems: you can receive both the original and a reflected signal from your own transmitter (on analogue TV this appears as "ghosting") or interference from TV transmitters that are normally too far distant.
The ITV/C4 multiplex of channels (ITV-1, ITV-2, ITV-3, ITV-4, CITV, C4, More4, E4, Quizcall) use a transmission "mode" called 64QAM, and it is sadly much more prone to these problems.
So, whilst a loft-mounted aerial will provide reception at some time, it will fail at others. The only real solution is to mount the aerial (or a new Class I aerial) outside on a pole, but some people report that changing the cable from the aerial to the set-top box to the high-grade satellite cable can also help.
The SCART connection, by the way, only carries a single TV picture, not the Freeview transmission multiplexes, so if this is disconnected it will result in degradation to every channel at once.
All questions
In this section
Thursday, 18 September 2014
I
Isla9:02 PM
MikeB: we were okay tonight after work too, haven't done a re-scan this week so it seems weird if something has just mysteriously updated?
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Friday, 19 September 2014
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MikeB2:56 PM
Have just rung up the Beeb, and the chap has logged what I said, and has passed on a link
to this site!
By the sound of it, we seem to be on the mend, but info and guidance would have been helpful!
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J
js3:25 PM
MikeB: Some background from digitaluk:
"Split NIT
In summer 2008, Freeview and the digital multiplex operators (DMOL) updated the network due to the introduction of many more services since the launch of the platform. This required the Network Information Table (NIT) to be split to carry more data. Early products with insufficient memory or that need to reattribute memory subsequently stop working."
I can't prove it was the cause, and have only examined the North West NIT, but ...
On 03/09/2014 the NIT was expanded from two to three sections [see note].
North West NIT, 2014-09-16 10:25, version_number = 20
section_number = 0
section_length = 752
section_number = 1
section_length = 947
section_number = 2
section_length = 382
By 18/09/2014 the NIT had shrunk back to two sections by removal of extraneous data.
North West NIT, 2014-09-18 10:55, version_number = 21
section_number = 0
section_length = 897
section_number = 1
section_length = 1014
This descriptor was removed:
descriptor_name = extension descriptor
descriptor_length = 155
descriptor_tag_hex = 7F
descriptor_tag_extension = 8
message_descriptor
[A Section is a syntactic structure used for mapping Service Information tables into Transport Stream packets. Sections may be variable in length. The sections within each table are limited to 1024 bytes in length, except for sections within the EIT which are limited to 4096 bytes.]
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MikeB4:36 PM
js: That sounds like it could be the problem, although I have to admit that some of that is over my head!
Although the Goodman's box continues to be sold (as well a similar boxes), its possible that the actual spec is a little old. Why the box should freeze, but then often work after a reboot, and why they sometimes don't respond to the remote is beyond me. And why BBC channels?
Since my box started to have problems a couple of weeks before the retune, could it be that Waltham might have changed the NIT early, and so the problem didn't show up generally until after the 3rd?
We await the BBC's reply with interest..
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Sunday, 21 September 2014
M
MikeB11:34 AM
Still nothing from the BBC, but while working yesterday, one customer also mentioned that his Goodman's box had the same problems, but had started working again, so at least we seem to be getting back to normal (I did advise him that a Humax PVR might be better for the long term).
There was also a gentleman with an 8 year old Panasonic suffering from a possibly not dissimilar problem, so it could be that older tuners (or at least their designs/software) have been hit by this. At some point, there will be more data broadcast, and its possibly wise to think long term if your buying another box.
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Nightjar5:20 PM
It must be said incidentally that while the BBC channels and/or Goodmans s****ybox have been 'behaving themselves' the channels in question are a little glitchy, especially when changing to a different one.
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Wednesday, 24 September 2014
I
Isla11:58 AM
I got a response from the BBC!
Thank you for contacting us.
I'm sorry to read that you've been having problems with your reception.
We're aware of a small number of viewers who have been experiencing similar issues. Issues include the Freeview receiver freezing' when tuned to a BBC service; the picture or system 'freezing' when changing from one BBC channel to another; being unable to access the Red Button; the system 'freezing' after accessing the Red Button service or coloured lines appearing at the top or bottom of the screen.
Although these issues occurred around the time of the 3rd September retune, following detailed investigation we believe this to be a coincidence, and the problems have in fact been triggered by an update to the BBC Red Button service.
We believe that our update is compliant with the specifications for interactive red button services and that there is an issue with these specific receivers.
However, to help viewers using these receivers we have been able to make a further change to our Red Button update. This modification does not need the viewer to take any action and appears to have resolved the issue in the short term, but we cannot guarantee that it will be possible to maintain this work-around forever. We are therefore working with manufacturers to see if they can implement a permanent fix.
Kind Regards
Matthew Degnan
BBC Audience Services
www.bbc.co.uk/reception
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MikeB1:29 PM
Isla: mine came this morning as well - the mystery is solved.
On the long term, we are going to need a bigger boat !
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Saturday, 27 September 2014
S
SquidgyJersey8:59 PM
SquidgyJersey: Thank you MikeB & Isla for your help & info.
On Wednesday lunchtime suddenly thought have not had to reset the receivers at work.
Whether Freeview TV's or set tops all now seem ok plus neighbours & colleagues report the same too.
Best regards & thanks again :-)
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MikeB10:48 PM
SquidgyJersey: We are fine for the moment, but if you read the email that the BBC sent to Isla (and me), you'll notice that they say 'we cannot guarantee that it will be possible to maintain this work-around forever. We are therefore working with manufacturers to see if they can implement a permanent fix.'
Since these are essentially relatively cheap boxes on a standard chassis, its going to be interesting to see if Goodmans etc spend time and money to sort out an update. Goodmans/Vestral might, but I'd be surprised if all the companies that supllied them do it.
As I quoted to Isla the line from Jaws, we are going to need a bigger boat, or should I say, a more up-to-date receiver. If you buying a new TV, then it should have an HD tuner in it, and this problem instantly vanishes, likewise with a decent PVR.
At some point, this sort of problem will crop up again, so its wise to think ahead. Still, its nice to watch something without having to pull the power lead out of the back of the box every so often!
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