menuMENU    UK Free TV logo Freeview

 

 

Click to see updates

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
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
Saturday, 4 January 2014
J
Joanne
10:00 AM
Preston

Thank you for your help Mike B. I am very pleased to say that the tv is up and running now. I will try the signal strength in future because I didn't know that it was possible to do this! Thank you again.

link to this comment
Joanne's 2 posts GB flag
Joanne's: mapJ's Freeview map terrainJ's terrain plot wavesJ's frequency data J's Freeview Detailed Coverage
J
jb38
sentiment_very_satisfiedPlatinum

11:10 AM

CLIVE JOHNSON : I am inclined to agree with MikeB with regards to checking out your aerial system, as although in my particular location the stability of Waltham's HD signal cannot by any means be classed as perfect over what it was a few months ago, the level of fluctuation in the signal is not of a sufficient magnitude to cause picture break up to occur.

The other point being, that my reception from Waltham is via diffraction (signal bending) by my location "not" having a clear line-of-sight with the transmitter, a situation where the summer and winter effect generally comes into the equation due to seasonal changes to the surface of the terrain etc, whereas on the other hand you are indicated as having a clear line-of-sight (likewise I suspect MikeB) and should not be experiencing the same type of difficulties as myself, that is excluding such as trees or any man made objects (buildings) causing obstructions to the signal path as the terrain indicator is only concerned with the ground surface and not what may be on it.

However, if at all possible I would try and enquire with say a neighbour to determine if others are also experiencing difficulties with HD reception from Waltham "if" their aerial is facing that direction and not Sutton Coldfield, because if they are'nt then this points to your aerial being the source of your problem.

You should still try a signal strength / quality check on C58, giving an update on the result.


link to this comment
jb38's 7,179 posts GB flag
C
CLIVE JOHNSON
2:02 PM
Leicester

Thanks again for further comments.
I have a top-quality indoor aerial aligned to Waltham-on-the-Wolds and for several months I have had good reception on this, including HD, with my LJ TV with integral tuner. Then suddenly in the last 2 days Channels 54 and 57 have become unwatchable, while channel 49 gives perfect results. A signal-strength test reflects that situation. Although officially W-on-the-W is our best station, this is not so because we are on the wrong side of a hill for direct-line-of-sight reception. Perhaps the weather has played a part??

We have a 4G filter fitted, one which came free in the post, and I do not know of any 4G transmitters near us.

We also have an outdoor aerial aligned to Sutton Coldfield, which gives us a much better signal; I route this into a Humax recorder, but this does not handle HD.

We have the TV tuned to Waltham so that we can get the East Midlands programmes.

Until recently this all worked fine!

link to this comment
CLIVE JOHNSON's 18 posts GB flag
CLIVE's: mapC's Freeview map terrainC's terrain plot wavesC's frequency data C's Freeview Detailed Coverage
J
jb38
sentiment_very_satisfiedPlatinum

3:49 PM

CLIVE JOHNSON: The terrain checker used (Megalithia) works in conjunction with a Street map post code converter to indicate the terrain between two points, the result of accessed by opening the undermentioned link which as you will see does not indicate any obstructions to the signal path.

However, judging by what you have now said with regards to you being on the wrong side of the hill for Waltham would suggest that some error has crept into the system, that is "if" the post code is accurate for your location and not just an area one which some are.

Needless to say that said by myself was based on the indications seen, but now that you have given an update / clarification on your situation this paints a somewhat different picture with regards to the problems being experienced and especially where 4G is involved, as anyone who receives 4G filters through the post has been assessed by AT800 as residing in an area with the potential to experience problems caused by a local 4G transmitter.


Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location


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

3:57 PM

CLIVE JOHNSON : You should phone the AT800 contact centre as they will give you a more detailed explanation of their reason for sending you the filter.

Contact at800 / DMSL | General Enquiries | at800

link to this comment
jb38's 7,179 posts GB flag
M
MikeB
sentiment_very_satisfiedPlatinum

6:34 PM

CLIVE JOHNSON: Why are you using a 'top quality indoor aerial' (hopefully loft at least) when you have an excellent signal on an external one? Ok, you might get a different local news, but there should be no problem getting HD on either.

If there is a problem with the signal strength on the Waltham aerial, even though you might be on the wrong side of the hill, why is there suddenly a problem? There are no leaves on the trees, its unlikely a new large building would have suddenly been constructed, so either its the reduced power from the HD mux, or its something failing within your own system, and since its C4 and ITV which have had a problem, logically it cannot be the mux. Which leaves the system and its wiring...

As for 4G - its unlikely there is a problem, and in any case, why would it leave you with zero signal?

link to this comment
MikeB's 2,579 posts GB flag
J
jb38
sentiment_very_satisfiedPlatinum

9:08 PM

MikeB: Just a little point about 4G. Although as yet there is no definite proof as to whether or not this potential source of interference is actually playing any part in Clive's problem, but though if it was then what Clive has reported is exactly what would be expected as being the symptoms of a 4G transmitter being tested out, as the swamping effect from a 4g transmitter on the wideband RF input stage of receivers tuner has a much greater effect on the channels received that are nearest to the 4G TX's operating frequency and gradually tapering off on the channels furthest away from it, C49 the BBC channel being exactly that, C29 being excluded from the equation as its only predicted as being able to provide a variable level of reception anyway.

If the aerial being used for Waltham is located in the loft then its much less likely (but not impossible) that a fault has developed where the coax is terminated into the aerials connector box, that said by myself on the assumption that a roof aerial was being referred to, although it would not do any harm to check same purely for elimination purposes.

link to this comment
jb38's 7,179 posts GB flag
H
Heather
9:20 PM
Cambridge

jb38: Hi, This my first use of this site because I have suddenly lost all the channels on Multiplex COM5 - ARQA - Arqiva A in postcode CB58QQ, Cambridge. Recently we have just had a big tree removed which was seriously degrading our signal leaving us with no BBC channels. Now that they are back and perfect but I have lost the likes of dave & E4+1 etc. I also have heard that 4G has just reached of in Cambridge and from this site I see there are several phone transmitters nearby. Any ideas please

link to this comment
Heather's 3 posts GB flag
Heather's: mapH's Freeview map terrainH's terrain plot wavesH's frequency data H's Freeview Detailed Coverage
M
MikeB
sentiment_very_satisfiedPlatinum

9:39 PM

jb38: Your quite right about the effects of 4G, but the one thing that tends to occur (looking back at the threads) is that when people suggest 4G as the root of their problem is that it almost always isn't!

Almost every time, its something else, and all too often a problem within their own system (OK - at least the ones who report back). Since a 4G filter has been fitted, all I'm saying is, it the most likely problem?

Even loft aerial systems can fail (corrosion, etc) but we both agree that no matter how unlikely it is, at least it should be eliminated, so that the problem can be identified.

link to this comment
MikeB's 2,579 posts GB flag
Dave Lindsay
sentiment_very_satisfiedPlatinum

9:57 PM

Heather: If you have a booster then maybe it needs turning down; the thinking here that it might have been installed in an effort to increase the signal level due to the tree.

Where a signal of too high a level is being received then it can appear as if the problem were the opposite which is too little a signal.

link to this comment
Dave Lindsay's 5,724 posts GB flag
Select more comments

Your comment please
Please post a question, answer or commentUK Free TV is here to help people. If you are rude or disrespectful all of your posts will be deleted and you will be banned.







Privacy policy: UK Free Privacy policy.