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Freeview reception has changed?

Why should my Freeview reception change when I have not changed anything?

Why should my Freeview reception change when I have not changed
published on UK Free TV

From time to time people find that their Freeview box, integrated set (idTV) or Personal Video Recorder (PVR) has lost many channels without any apparent changes.

There are a number of factors to consider

Freeview is broadcast on digital multiplexes. This means that, once broken down into a stream of bits, each television channel is combined into a single transmission of 1s and 0s. This means that reception is of the multiplex first if this is lost it affects all the channels in the multiplex in the same way.



The signal strength received by the box or TV for a particular multiplex from a given transmitter determines if the data can be received or not. So, a poor signal results in no data, an adequate signal in perfect data and a low signal in either none or all.

Poor digital signal levels do not result, as they do with old-fashioned analogue television, in a sub-standard picture or sound. Poor signals often result in a perfect data-stream, but are prone to periods of no reception. Sometimes this will be for hours, but can also be several times a minute when caused by induction from fridges, freezers, central heating systems, two-stroke scooters, baby monitors and so on.

If you have lost ALL your Freeview channels

First disconnect the aerial lead from the Freeview box or TV set and reconnect it and then follow this reset procedure to scan for channels again. If this does not result in services being restored, check the Freeview transmitters page to see if there are any engineering problems with your local transmitter.

How to check all cables, connectors and aerials

The RF connectors need to be in very good condition to work. There are two general types:

Factory-fitted connectors are very reliable as they cannot easily be taken apart, but they can be damaged by wear and tear. On the female-type the central section is often composed of two parts which can often be forced apart, resulting in a poor connection you can push them back together if this has happened with a pair of tweezers. On male connectors if the central pin is damaged, you will need a new cable. If there are any loose partials in the connector, remove them.

Another problem with these cables is that quite easy to sprain the connector at the back which causes little obvious external damage, but disconnects the internal connection. This happens often when a set-top box is pushed backwards into a cabinet.

Hand made cables can also suffer from similar problems to factory made ones and they are also prone to accidental damage from a cable being pulled. If such a connector is not firmly attached to the cable, the connector may need refitting.

Cables

Make a visual check of the cables. There are a few basic checks:

If the cable has been slashed or cut, it will not be very effective or reliable. If such a cable is fitted externally, this can allow rainwater to enter the cable and this will reduce the signal levels.

You can easily damage an RF cable by crushing it, for example in a door. If the outside of the cable has a permanent kink in the cable or has been very tightly looped, this could be the site of damage.

Aerial

For reliable and effective Freeview reception, a rooftop aerial is required. It is hard to make a visual check of such an aerial without putting yourself in potential danger.

You can make a visual check of the route between the aerial and the transmitter. Any form of obstruction will damage the digital signals. In particular trees coming into leaf, as these will leech the signal before it reaches your aerial. This applies to both trees adjacent to the aerial and at a distance.

Another common problem in cities is building work. A large crane will often change position many times during the day, and if this is between your aerial and the transmitter this can reduce the signal levels in an unpredictable way.

If your system uses a booster, the power may have failed. Check the fuse to the power to the booster.

Weather problems

There are two main weather problems that effect Freeview reception.

The Inversion Effect: please see What is the Inversion Effect and why does it effect my Freeview TV reception?



Wind: high winds sometime can dislodge the aerial this results in a poor signal.

Rain: poor or old cables can fill with water and this results in a poor signal. If this happens, the cables will require replacement.

Help with Freeview, aerials?
How do I get a test card with Freeview1
I would like to know if it is possible to receive UK terrestrial Freeview servic2
I have been told I would receive too much singal from my Freeview tansmitter as 3
Can my Freeview box receive more than one BBC and ITV region?4
Is it true that my 87 year old mother is entitled to a FREE upgrade when the ana5
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In this section
Official aerial installers guide to the TV spectrum future1
Which free digital TV system will give me the most reliable reception?2
High pressure causing channel loss through "Inversion"3
Digital Region Overlap4
Two frequency interference 5
Single frequency interference6

Comments
Wednesday, 1 January 2014
C
CLIVE JOHNSON
2:29 PM
Leicester

My TV is tuned to Waltham-on-the-Wolds and until recently I had good reception of all appropriate Freeview channels.

Recently I was prompted to do some updates and auto scans, which I did.

On trying to receive the new HD channels (BBC4 , which was annonced this morning in connexion with the New Year's Day concert) I discovered that I could not get BBC1HD and BBC2 HD, which previously I could. I had a "no signal" notice.

I did a new auto scan and after that I could get the HD channels (not BBC4) but the quality was very poor - unwatchable - while the SD channels were fine.

I have seen a few posts about trouble with HD but did not take particular notice as I did not think I was affected.


link to this comment
CLIVE JOHNSON's 18 posts GB
J
jb38
sentiment_very_satisfiedPlatinum

2:56 PM

CLIVE JOHNSON: You should carry out a signal strength check on the offending channels as your TV or box has possibly stored that used by Sutton Coldfield, the reason for the test being to determine the mux channel number which on most Freeview devices is usually shown along with the strength / quality of the signal and with same being cross checked with the undermentioned channels used by both stations.

Waltham - 49 (BBC) - 54 (ITV) - 58 (HD) - 28 (ITV3 etc) - 56 (Pick TV etc) - 57 (ITV4 etc) - 31 (new HD)

Sutton C - 43 - 46 - 40 - 42 - 45 - 39 - 33 listed in the same order as above.

link to this comment
jb38's 7,179 posts GB
J
jb38
sentiment_very_satisfiedPlatinum

3:07 PM

CLIVE JOHNSON: In addition, needless to say that should you subsequently find that the problem is being caused by Sutton / C's muxes having been picked up then the only way of avoiding this is to blank out everything previously stored by auto tuning with the aerial removed, this then being followed (once aerial is reconnected) by manually tuning in each of the muxes used by Waltham with reference to that listed in previous posting.

link to this comment
jb38's 7,179 posts GB
C
CLIVE JOHNSON
8:51 PM
Leicester

jb38: Many thanks for the responses.

I've now done a check on signal strength etc. from Waltham. It lists channel 58, which is correct for Waltham HD, and not Ch. 40 which is think is HD from Sutton Coldfield. Am right in thinking that I am correctly tuned in for Waltham HD?However, the signal strength for Ch 58 is shown as about zero, and it is preceeded by a red triangle with an exclamation mark inside, like a road warning sign. What does that mean? What should I do? Is this just a temporary loss of service (I hope!)

link to this comment
CLIVE JOHNSON's 18 posts GB
J
jb38
sentiment_very_satisfiedPlatinum

9:34 PM

CLIVE JOHNSON: Yes, 58 is indeed Walthams HD service, but on checking my previous reply I have just noticed a typo error I made on the ITV3 mux,, this being C29 and not C28.

As far as C58 is concerned, I just carried out a signal check on that channel and although its being received OK in the Stamford area the strength is down on what it usually is, and with a considerable level of fluctuation on the quality being seen.

HD is more critical over SD as far as bad connections on the coax is concerned, but if you are receiving ITV1 OK and also ITV4 (mux 57) then I would just wait and see if the situation improves any over the next day or so, if it doesnt we can take it from there as interference from 4G affects channels from C60 downwards, that is should you reside in an area not terribly far away from a source of 4G.

link to this comment
jb38's 7,179 posts GB
J
jb38
sentiment_very_satisfiedPlatinum

9:47 PM

CLIVE JOHNSON: By the way, the red triangle referred to is just the TV warning you of an insufficient level of signal being received for the decoder to operate correctly.

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jb38's 7,179 posts GB
Friday, 3 January 2014
J
Joanne
6:29 PM
Preston

I wonder whether you could help please? Yesterday, the TV started to show pictures that were breaking up into large and noisy pixels. The aerial is in the loft and the TV has an integrated Freeview. We live in Preston , Lancs and it has been fairly windy and wet, but nothing too unusual. I have tried retuning several times, but it doesn't seem to help.

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Joanne's 2 posts GB
C
CLIVE JOHNSON
6:57 PM
Leicester

Many thanks to JB for the interest and help.Today, 3rd.January, our BBC1 AND BBC2HD channels are still scrambled, but now Channels 3 and 4 are also scrambled. But BBC1 and BBC2SD, all from Waltham, are perfect. We haven't seen any notices of transmitter trouble,so what is going on??

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CLIVE JOHNSON's 18 posts GB
M
MikeB
sentiment_very_satisfiedPlatinum

11:21 PM

Joanne: Check your signal strength (try not to retune, you just lose the original transmitter) - if its really low, then there is a problem with your aerial system. As you can see, the transmitter is fine, and you should be getting an excellent signal.

If its too high, well, you are only 20km from the transmitter!

link to this comment
MikeB's 2,579 posts GB
M
MikeB
sentiment_very_satisfiedPlatinum

11:26 PM

CLIVE JOHNSON: Waltham is fine (I'm actually further away than you are), so perhaps you'd better check your signal strength and then your aerial system.

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MikeB's 2,579 posts GB
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