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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
Friday, 22 February 2013
G
Graham Cole
9:29 PM
Liphook

I have installed an aerial in the loft , run brand new cable . My postcode is GU30 7DX .
I have positioned the aerial to face the hannington transmitter near Basingstoke but cannot get any channels . On one occasion when I re-tuned I appeared to pick up 30 channels but they were mainly radio channels but they never played . Any thoughts .

link to this comment
Graham Cole's 1 post GB
J
jb38
sentiment_very_satisfiedPlatinum

11:50 PM

Graham Cole: There is a number of stations that appears as being possible to pick up from your location Hannington @ 25 miles / 309 degrees being the only one indicating reasonably good, I feel that your best policy would be to scrub anything already stored by resetting your TV or box and then using the "manual" tune facility to tune in each of Hanningtons muxes one at a time, storing the results.

First though just to make sure that your loft aerial is correctly positioned go into your devices manual tune screen and enter Hanningtons mux Ch45 (BBC) but do NOT press search or scan, because as soon as you enter Ch45 its signal strength / quality should be indicated on the bars, just leave that screen on and use it for trimming the aerial alignment for maximum quality, albeit with the assistance of another person observing the screen.

You can then press search followed by storing the results of the search, once completed use exactly the same procedure to capture the remaining muxes.

Hanningtons channels being /

45 - 42 - 39 (HD) - 41 - 44 - 47.

PS: If by any chance your initial manual test on mux Ch45 results in a very low reading and which is not helped any by trimming the aerial, then give an update on this as you might require the aid of a signal booster.

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jb38's 7,179 posts GB
Saturday, 23 February 2013
J
jb38
sentiment_very_satisfiedPlatinum

8:07 AM

Graham Cole: Just to add to that already said, when I referred to your loft aerial being correctly positioned this does not necessarily mean correctly angled from one fixed position but also to experiment with it in various parts of the loft, and with the reason for saying that being that the signal path between your location and Hannington is seen to suffer from obstructions at various points along the way starting from roughly 7 - 16 miles, 12 miles being the main one and these type of situations generally demands a certain level of experimenting to obtain the best position, this being where loft mounting generally scores over roof installations, and so when trying the initial signal test I referred to on BBC also try a few positions to the left or right just to make sure that you have the best spot, it would also be prudent to carry out the same test on say Ch41 (ITV3) as the six muxes used by main transmitters are seldom ever received at the same strengths, and of course the three commercial channels from Hannington only transmit on half the power of the PSB channels.

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jb38's 7,179 posts GB
Wednesday, 27 February 2013
T
Tom Morgan
11:17 PM
Manchester

Brian Clark: the same problem you described has happened to my tv over the last few days. i live in m20, have tried retuning and changing leads etc. no difference. if you managed to correct the problem can you tell me how please?

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Tom Morgan's 1 post GB
Monday, 1 April 2013
J
Julian Parker
1:45 PM

I am contacting you on behalf of a person who has moved house and currently does not have her pc connected. She lived in Tytherington and received Points West as her local news station. She moved to Alveston recently and still received the same station. She had a message flash up on her tv advising her to re-tune her channels. This she did by re-tuning her digital dvd player which has Freeview and now her local news channel is BBC Wales. Would this possibly be due to her closer proximity to the Welsh transmitter or the direction her aerial is pointing?

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Julian Parker's 3 posts GB
Dave Lindsay
sentiment_very_satisfiedPlatinum

2:40 PM

Julian Parker: It wouldn't necessarily be due to proximity.

When the automatic tuning scan is run, a receiver scans or listens to all frequencies so as to see what it can find. At the end, it makes a 'decision' of which transmitter to go with, should more than one be found.

In this case, evidently and for whatever reason, the decision is to go with, I assume, Wenvoe.

The workaround may be to have the aerial unplugged during the part of the scan where Wenvoe's channels are, although they are only just below Mendip's.

Have the aerial unplugged up to about 55%. If, having done this some channels are missing (because the aerial was out until a bit too late) and there is a manual tune option, then add the missing ones manually:

COM4 - ITV3 etc is on UHF channel 48
PSB1 - BBC One etc is on UHF channel 49

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Dave Lindsay's 5,724 posts GB
K
KMJ,Derby
sentiment_satisfiedGold

2:55 PM

Julian Parker: This will happen in the Bristol Channel area because the Wenvoe transmitter (BBC Wales) uses lower frequencies than the Mendip transmitter (BBC West), this results in the scan finding Wenvoe channels first, which are duly entered into the channel list, then when Mendip channels are found any which carry a variation will be placed at the end of the channel list - usually in the 800s, as the LCN (normal) positions are already occupied. If the Mendip signal is stronger than the Wenvoe signal some tuners will overwrite Wenvoe channels with identical content to store the transmitter with the strongest signal, which sometimes results in an assortment of channels from each of the available transmitters. The direction that her aerial is pointing will usually determine which transmitter offers the strongest signal, but in the first instance channels on lower frequencies are always scanned first.

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KMJ,Derby's 1,811 posts GB
J
Julian Parker
4:13 PM

Thank you everyone who have replied with advice. My friend has advised me that her missing programme appears on channel 800 as suggested and the stronger channel appears on BBC1. When I have time I will go down to Bristol from Cheltenham and do a programme position swop for her.
Many thanks for all your help.

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Julian Parker's 3 posts GB
Dave Lindsay
sentiment_very_satisfiedPlatinum

4:14 PM

Julian Parker: You will probably find that all services on PSB1 are 'wrong'. That is, the Mendip ones are in the 800s. It probably won't just be BBC One that is wrong although it will be most obvious as it has regional variances, as does BBC Two sometimes.

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Dave Lindsay's 5,724 posts GB
J
Julian Parker
5:24 PM

Thank you Dave. I will also check these other services when I go down to Bristol. She did read them back to me and I thought myself that they were out of order.
Thank you.

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Julian Parker's 3 posts GB
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