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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
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
Thursday, 27 September 2012
B
Bryan
8:24 PM
Cardiff

Since the Olympics, our Sony svr-hdt500 has "lost" all bbc channels and has be retuned every morning. I've tried factory reset and retune; this resolves the problem until the following morning, when the problem recurs!

We live in cardiff
Use roof arial
Welsh channels selected as region 1
It seems the Sony box is trying to find the English NBC channels instead of the welsh (if this makes sense)

Any ideas for a solution gratefully received.... Why did we go digital again??

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Bryan's 3 posts GB flag
Bryan's: ...
Dave Lindsay
sentiment_very_satisfiedPlatinum

9:05 PM

Bryan: The "forgetting" channels usually happens because there isn't enough memory. This is caused because when the scan is performed it stores all the signals (from all transmitters) that it finds. In this case I suspect that your receiver may be opting to go with Mendip's BBC multiplex on channel 61. See whether this is the case by bringing up the signal strength screen on BBC One.

I assume that your aerial is directed to Wenvoe which is to your south west (231°) and horizontally polarised. In which case, wipe the channel memory (probably by running the automatic tuning scan with the aerial unplugged). Then manually tune in the six multiplexes: 41, 44, 47, 42, 45, 49.

C47 is the HD once and C49 will move to C39 in March next year.

The manual can be downloaded here:

http://www.sony.co.uk/pro…#tab

Page 36 describes the procedure. It also mentions "Automatic Service Update" on the bottom right. If this in practice does a full scan when unattended then it probably wants setting to Off else you'll likely have the same result.

Why doesn't selecting Wales region not choose the right BBC channel? Good question, I don't know.

Picking up the wrong transmitter (and hence possibly wrong region) happened just as much in the days of analogue because there are many places of overlap.


Going back to what I said about running out of memory, this is only caused because signals from multiple transmitters have been picked up. Mendip is on the highest channels and is therefore scanned last. In fact C61 is the highest of the lot. The trick, therefore, is to prevent it from scanning other transmitters before one's own. This is akin to ensuring that a child doesn't fill itself full of sweets before mealtime (so that there is enough room for the proper meal).

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Dave Lindsay's 5,724 posts GB flag
B
Bryan
9:32 PM

Thanks for your comprehensive answer Dave. Ihaving just completed a factory reset and manual retune, bbc1 is now reported as follows:

Bbc1 wales
Channel 41
Strength 96%lookong
Quality 100%

Channel is being received well & fully able to view. Hopefully we've cracked it.... Will confirm tomorrow morning if we don't need to retune.
Thanks again
Bryan

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Bryan's 3 posts GB flag
Friday, 28 September 2012
B
Bryan
7:09 AM

Thanks to Dave Lyndsay; my problem is fully solved. Turning off "automatic service updates" (which is "on" by default) was a critical factor that I had previously missed. A diagnostic symptom here seems to be that I had previously had to retune *every* morning to recover missing channels, but the recovered channels were then fine until the following morning.
Thanks again
Bryan

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Bryan's 3 posts GB flag
Dave Lindsay
sentiment_very_satisfiedPlatinum

10:02 AM

Bryan: Perhaps the memory issue I described isn't at play and maybe it is all down to it doing a full retune every night. Either way, it's probably best to carry out the procedure of manual tuning to void the wrong channels.

Good to hear that you got it sorted.

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Dave Lindsay's 5,724 posts GB flag
Thursday, 11 October 2012
R
Richard Dennis
5:27 PM

Hi We have a technika tv in the dining room that comes off a splitter box (3 way ) So we can pick up Sky on analog and switch over to digital for all free veiw options . Since being told to retune digital we can no longer see much , it's like looking through milk .. But analog is perfect so it's surly not a problem with tv ... Help .....

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Richard Dennis's 1 post GB flag
J
jb38
sentiment_very_satisfiedPlatinum

9:27 PM

Richard Dennis : These symptoms suggest that "if" your local Freeview station has recently changed its operating channel numbers then one of is now on the same channel as is being used by your Sky boxes analogue modulator link, something which can cause problems such as described dependant on the signal level being received from the Freeview transmitter.

You should try changing the RF modulators channel to say 66 - 69 and check if the Freeview problem has cleared, if so then retune your TV whilst on analogue to pick up the modulators new output channel.

If this does not work then it will be necessary to provide info on your location, this in the form of a post code or one from nearby e.g: a shop, as only then can details of the transmitter involved be checked out.

Just an afterthought, "before" carrying out the procedure mentioned try by-passing the Sky box by linking your aerial feed directly into the coax lead that goes to the splitter, as should that action clear the Freeview problem then this confirms that it is the Sky boxes modulator that is causing the problem.

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jb38's 7,179 posts GB flag
Saturday, 20 October 2012
M
Martyn
11:46 PM
Weymouth

I live on the West side of Weymouth and have opted to tune to the Stockland hill Tx rather than the local relay because of the additional channels available. I have run like this, quite happily, since the switch from analogue to digital; until 17th Oct 2012, that is. Since the retune I regularly lose ITV1, Ch4, Ch5, BBC1HD, BBCHD, ITVHD, CH4HD and heaven knows what else. Can someone please explain what changes were made on this date and try to explain the loss of channels.

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Martyn's 1 post GB flag
Martyn's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage
Sunday, 21 October 2012
J
jb38
sentiment_very_satisfiedPlatinum

12:25 AM

Martyn: I dont think that its really anything to do with the EPG changes that took place then, but more the case that the retune you carried out has resulted in your box picking up incorrect channels from another transmitter.

Stockland Hill transmits on: Ch26 (BBC) - Ch23 (ITV1) - Ch29 (HD services) - Ch25 (ITV3 etc) - Ch22 (11 Pick TV) - Ch28 (15 Film 4) and so carry out a signal check on each of these channels and check if the mux channel being indicated corresponds to these mux channel numbers on the list, if not then carry out a retune with the aerial disconnected to blank out the tuners memory, then after having reconnected the aerial carry out a manual tune one at a time to recover these channels, storing anything received.

By the way, you are only predicted as being able to have having poor reception from all three of Stockland Hill's commercial channels, and so I would keep this in mind if any programmes are difficult to receive.

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jb38's 7,179 posts GB flag
J
jb38
sentiment_very_satisfiedPlatinum

12:32 AM

Martyn: Meant also to say, that when you had opted to tune to Stockland Hill rather than the local Weymouth transmitter, you aerial was changed to horizontal polarity as well as facing 297 degrees?

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jb38's 7,179 posts GB flag
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