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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-standardpicture 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.
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.
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.
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.
There are two main weather problems that effect Freeview reception.
Your comments are always welcome. Please use the form below to add your thoughts or questions to this page. We will get back to you as soon as we can.
jb38 Saturday 26 May 2012 11:23PM
Mark Hayman; Yes no problem, although depending entirely on the tuning menu system in whatever device you are using offers you could just manually tune in the BBC from Tacolneston on mux Ch55 then use the channels up-date or whatever your menu calls it to fill in the remainder of the channels as this somewhat shortens the procedure, its just that the tuning menu facilities offered in different brands of devices are all different, this making it impossible to give exact instructions.
We receive from the Heathfield transmitter (and not Midhurst as is the norm for RH13 9HQ). This is because of landscape considerations and a very large oak tree.
We have now completely lost BBC1,2, 3 and 4 in spite of re-tuning. The technical information seems to suggest that this is a permanent loss (although the information is very technical and hard for a non-engineer to interpret).
I don't recall anything in the switchover suggesting we would permanently lose BBC. Please can you advise?
JS: The signals after switchover are different to those before switchover.
Before switchover they are transmitted using 2k mode and afterwards they use 8k mode. Some older equipment will not work in 8k mode.
At the first stage of switchover, the standard definition BBC services change to 8k mode. The rest stay in their pre-switchover state (in 2k mode).
Hence after the first stage of switchover, an affected piece of equipment will not be able to receive the new 8k signals. At the second stage of switchover, it will no longer pick up anything because the remaining 2k signals have been turned off.
This is why I asked what the model is so the specifications may be checked on as to whether it will function in 8k mode.
There are six multiplexes before switchover and six after switchover. At switchover, some services move multiplex. Consequently, between the first and final stages of switchover, BBC Four and BBC Parliament are carried on two muxes simultaneously.
See this page for the six muxes before switchover and the six after (you may need to press F5 to see the graphics below the headings):
Prior to yesterday, Heathfield was broadcasting the six muxes that are under the heading "Before switchover configuration" (on the page I've just linked to). You will note that BBC Four and BBC Parliament are carried on Mux B whereas the other BBC services were on Mux 1.
After switchover, BBC Four and BBC Parliament are carried on a multiplex along with other BBC services (BBCA mux).
At the first stage of switchover, pre-switchover Mux 1 is replaced with post-switchover BBCA (in 8k mode). The other five pre-switchover muxes continue as they were (in 2k mode).
At the "end" of switchover in two weeks time, the other five pre-switchover muxes will be replaced by the other five post-switchover muxes.
Hence, between the first and second stage of switchover, BBC Four and BBC Parliament are carried on (post-switchover) BBCA and (pre-switchover) Mux B.
From what you describe, you are missing BBCA. I guess that the BBC Four that you have on number 803 is likely to be that which is carried on Mux B.
Receivers usually give the UHF channel number (equivalent to frequency) that they are tuned to and this is usually given on the signal strength screen. Go to 803 and bring up the signal strength screen and you will probably find that it is tuned to C47, which is Mux B from Heathfield (and not C52 which is BBCA).
Stu: You need to wait two weeks for DSO stage 2 to take place on 13th June 2012. If your aerial is pointing to the Newhavenrelay you will then be able to receive Mux D3+4 (ITV1, ITV2, C4, C5, More4, E4, ITV1+1 and C4+1. The HD channels will also be available if you have a DVB-T2 receiver. The COM muxes will only available if you have a signal from a full service transmitter, as the Newhaven relay is a PSB only transmitter.
Only transmitters that carried low-power Freeview before switchover will carry all Freeview channels after switchover. This is because the Commercial (COM) broadcasters do not have a "Public Service" obligation and operate purely on a profit-making basis. They stick to the biggest transmitters to cover the greatest amount of the population and lowest cost.
So the Newhaven transmitter will be a Public Service Broadcaster (PSB) one only.
If you can receive from another transmitter such as Heathfield or Whitehawk Hill, then you may be in with a shot of watching the COMs. If not, then you will only be able to receive the PSBs via terrestrial Freeview.
i have a question a the switchover was supposed to be completed in the west sussex area everything was working fine but now i have lost all the channels from multiplex A. have re-tuned and reset my box but still no joy. tried the the postcode checker and it has returned the answer that digital switch over is complete in your area. just for info my postcode is BN17 5HE
George Parker Friday 1 June 2012 7:38PM East Grinstead
I am continually having to retune from the East Grinsteadtransmitter as we lose all but the BBC channels. 11 DT and 11 Radio. Why is this? I am hoping to redirect to the Heathfield transmitter later this month; will this be better service?
Brought a technika freeview tv from tescos 2 months ago and all was working fine.
A week ago we started losing channels but when we retuned they came back. It happened again on Thursday night and after retuning as usual we have nothing. No freeview and no analogue.
An error comes up saying check aerial but that is fine. The tvs in the rest of the house work perfectly and all cables are plugged in.
I'm in the LE4 postcode of Leicester.
Any help would be greatly appreciated
I've given the channel numbers for Sutton Coldfield so you can see if any are tuned to it.
If it turns out that it is picking up Sutton Coldfield when it should be choosing Waltham, then run the automatic tuning scan with the aerial unplugged up to 60%. This will miss out Sutton Coldfield because it uses lower frequencies than Waltham (except for one of Waltham's).
According to page 18 of the manual I linked to, the Technika sets have a Manual Search option. Use it to tune to C29 to add ITV3 from Waltham.
Having performed this retuning, you can then check to see that the channels are tuned correctly, as described above.
It may also be useful for you to know that the services are broadcast in groups. See under the heading "After switchover configuration" on this page (you may need to refresh by pressing F5 if you are using a PC in order to see the graphic):
Frank: Just a little point concerning Waltham, "if" by any chance you are receiving your signal from there, then engineering work has being going on all of last week and with randomly timed breaks in transmission having taken place during the entire week.
The other point being, that although unfortunately its a commonly done thing, but you should try to refrain from the immediate temptation to carry out a re-tune if a blank screen is discovered when a programme channel has been selected, as 99% of the time the channel will still be stored in your TV's tuners memory but is being received at a strength that is just under the reception threshold level for your TV to resolve a picture, but as soon as you press "search" or "scan" then everything already stored in the tuners memory is immediately wiped out and requiring frequent re-scans to recover them, whereas all that would have been necessary was for checks to be made now and then to see if they had recovered.
I live literately across the road from the Hastings transmitter and have enjoyed full signal for years. as soon as the switch-over happened I lost 1 2 bbc3 and the news channel. I did a reset bit still am missing these channels. I cannot get 2 analogue either. Has anyone got a suggestion?
Now the picture on my Samsung digital TV is fine, but the picture on the (cheap) digital TV in the bedroom is unwatchable as the picture and sound break up. It's the same story with my Sagem digital recorder - programmes watched on the Samsung TV via the Sagem (either live or recorded) are unwatchable.
I'm using an X Beam high gain aerial, showing 70db/uV at the mast head (using a cheap signal strength meter) and distributed to five TV points via a splitter/amplifier in the airing cupboard.
I've tried a signal amplifier on the aerial lead to the TV. it increased the signal strength to 90db/uV, but didn't improve the picture.
I note that I'm on the edge of a weak signal 'puddle' in a generally high signal strength area. Do you think a new aerial would make any difference? By inspection I think my current aerial is an XB10A, but I don't know how to tell an XB10A from an XB10B.
Graham Brookbanks: Although you have not specified any particular channels that are the main subject of complaint, the question would be "if" you have turned your aerial around to its vertically mounted position? as the vertically polarised transmissions from Rowridge are all on 200 kw whereas on horizontal the commercials are restricted to 50kw.
However, as you are located at only 22 miles away from Rowridge have you tried a test using a set top aerial? as if you receive a reasonably good signal by using that then it can indicate that rather than by tying another booster you should be incorporating an attenuator in line to avoid overloading your tuners input stage.
My reason for saying this is, that Samsung tuners are not particularly sensitive and will work with an excessively high level of signal that can cause problems to TV's or boxes with more sensitive tuners, and so a test using set top aerial gives an approximate indication of the signal strength being received in a given area.
You cannot actually trust db indications taken on cheaper types of signal meters unless of an electronic type in the price range of around £100.00+ or so absolute minimum.
Graham Brookbanks,Eastleigh.The difference between an XB10A and a XB10B is simple.The XB10A is a group A X-Beam coloured red at its tips,while the XB10B is a group B X-Beam coloured yellow at its tips.Apart from the different coloured tips they are the same aerial tailor made for loft installations.The group B X-Beam (yellow tipped) is the wrong aerial to use on Rowridge transmitter as it is an all group A mast,but the group A X-Beam you stated (red tipped) is the right aerial as such.
Try changing the polarity of your antenna to vertical as the commercial multiplexes,SDN,ArqA & ArqB on horizontal polarity from Rowridge are on 50kw yet 200kw on vertical polarisation,it may just work.
Graham Brookbanks: The other point I meant to mention was that its not so much the signal strength thats important but more its quality, and should you be located in a somewhat iffy area for reception then the quality will usually be seen to fluctuate quite considerably even although the strength may not be doing so to the same extent, so maybe you could give an indication of what its observed as being.
ive been strugling with all bbc channels for few months now and then lost them .
Then e4 and the odd few just when distorted so got peed off with the channels and watched 5 USA and 5 * .. quest was a favourite .. i lost them a few days ago ..
now tonight i have scanned and acanned ... SAMSUNG tv ( new ) and ive lost all channels apart from 8 :(
ive done everything it says on the freeview website and its still the same
That said though, "if" you are located in one of these properties where your aerial is facing into a large tree located close by then this could well be the reason for your difficulty as nothing blocks a signal more than tree leaves, and especially so if wet.
My post code is ME3 9EA. I can get all the Freeview channels and the picture is very good but I keep losing the BBC Channels and have to keep re-tuning. And I mean daily. Also I can get the TV Guide for all Freeview channels including BBC 4 but not for any of the other BBC Channels.
Do you think this will sort itself out after the 2nd phase of the switchover?
To be honest, I was quite happy before the switchover and if I'd had a say, I would have voted NO.
KAREN SMITH: If you are receiving Freeview from Bluebell Hill (at 7 miles) then your problem could be caused by the signal you receive from the BBC mux being excessively high, as the BBC (and only BBC) is transmitting on 20Kw whereas ITV is only on 4Kw, so needless to say that if you are using any form of booster then this has to be by-passed.
Should though you not be using one then purely for a test try a set top aerial, but if you cannot access one then try the test using a short piece of wire (about 18") pushed into the aerial socket of your TV or box, if either test stops the BBC from vanishing then you will require to purchase an attenuator to place in line with the aerial socket on your receiving device, one rated at about 6db or thereabouts being suffice.
It should be noted that "if" this is the problem then it will get worse on the 27th when all muxes start transmitting on high power.
KAREN SMITH: Make sure you do a full reset, deleting all the existing channel information. Many boxes/TVs have two stores for channels, a temporary one and a permanent one, with the temporary store cleared when you turn the power off. If scanned for channels, some of them don't overwrite channels they already have in the permanent store, putting them only in the temporary store. You may have one of these.
To do a full reset, look for an option called something like 'First Time Installation', 'Full Retune', 'Factory Reset', 'Default Setting', or 'Virgin Mode'. It may be on a System or Software Update menu rather than on the tuning menu. Some manufacturers have provided specific information for the model at TV Re-tune .
If it still doesn't store the channels properly, it may have a limited amount of permanent channel memory. In this case, do the full reset with the aerial unplugged. When it completes the scan, do a manual retune and tune in C46 first, then C24, C27, C42 and C39. You can ignore C45 as it only carries duplicates of some BBC services, and Sky Sports 1 and 2 which are only viewable on BT Vision or Top-Up TV equipment with a suitable viewing card.
Next Wednesday, you should repeat the same process.
Hi. Continuing from my previous problem. I managed to retune the digital tv (from Channel 30 upwards) and got back all the missing bbc channels. However the signal breaks up making these bbc channels un-viewable. Note that other channels are fine. Any ideas? The aerial is still pointing towards Tacolneston.
Mark Hayman: The problem you might be having is that even although your TV is tuned to Tacolneston the tuner is still likely to be sensing the presence of a strong RF signal in the locality and being from Thetford's relay, as tuner inputs being wideband are not affected by channel selection, and a strong RF signal being sensed will cause the tuners auto-gain circuit to automatically reduce its sensitivity to avoid and overloading situation occurring, and with this unfortunately affecting all channels including the one you prefer to receive from, Tacolneston.
Its not terribly easy to overcome problems like that without experimenting with alternative aerial positions, and so the obvious question would be to ask where your aerial is installed? and secondly was your aerial originally installed for Tacolneston with it being mounted horizontally and facing approximately 64 degrees? whereas the Thetford relay is @ 1 mile / 278 degrees with the aerial being mounted vertically.
Ruth,Havant.Is your new outside aerial facing Rowridge polarised horizontally or vertically.And if so is it a group A (red tipped),a group K semi-wideband (grey tipped) or a group W wideband (black tipped) aerial.Have a look tomorrow (too dark now) at the colour tips,at your location which is officially a poor signal area (over 30 miles from home to mast) if its coloured black then your group W wideband aerial (if it is ?) is the wrong aerial to use on an all group A transmitter such as Rowridge in a poor/marginal aera itself.And at the same time if the polarity is horizontal it should be vertical polarisation for better results.
If you leave a full postcode,not a partial one,we should be able to give you more assistance as such,this is to ascertain the reception possibilities in your locality.
Daniele Wiseman Tuesday 10 July 2012 9:14PM Altrincham
I'm so pleased I've stumbled across this site. I've been so dissatisfied with the response from BT! I am in WA15 9AR and our television comes through a BT Visionbox to a brand new Samsung TV. We also have two smaller Toshiba TV's in the house, one connected to the aerial and one with an indoor aerial. The Toshiba connected to the aerial works perfectly all the time. All TV's have Freeview. The main TV has suddenly stopped working during the day. I sort of ignored it because I wondered if it was the Digital Switchover. But this started end May (or at least that's when I noticed it due to having to take some time off work)During the day (not first thing in the morning) all channels show the message Freeview signal low level or poor quality. If we switch BT Vision off, the TV shows No Signal for it's built in Freeview as well. Scanning for channels reveals 0 channels. At teatime, we might get 17 channels, it's usually 7-8pm before we get all our channels back and then it's fine all evening. BT had me reboot, check cables etc. No crane. Weather been OK compared to rest of the country. So could be aerial but I can't afford to pay for them to come out if it's not and as TV works in the evening I don't know enough to be persuaded it is the aerial and am leaning towards the signal. Can you help? We've missed so much including Wimbledon and my kids have exhausted recorded TV!
Daniele Wiseman: Winter Hill located @ 18miles / 338 degrees from you appears to be the station that serves your area and with the reception being predicted as being good across all six muxes. If the signal vanishes when you switch the BT visionbox off the that suggests that you are looping the aerial for the TV through it, and if you are then try connection the aerial directly into the TV and then carrying out another re-tune.
If your Toshiba works OK all of the time can you clarify what aerial its using? as I wasnt quite sure if you meant the indoors or outdoors one.
We have two Toshiba TV's - downstairs we use an indoor aerial. Upstairs we have an aerial which comes through the wall and goes into the TV. The house is rented and there are two different aerials but they are located together and pointing in the same direction. I don't know which aerial is feeding which TV, I just can't see. But again, I don't understand why we only lose the signal during the day. Does this help?
Daniele Wiseman: Losing the signal through the day can be caused by a variety of things, but signals received from anywhere vary in strength during over a 24 hour period through natural atmospheric reasons as well as "slight" drops in the mains supply voltage due to demand, and this can affect transmitters as well as receivers, and although these are of a minor nature if anyone has a less than ideal aerial arrangement or the signal they receive is slightly deficient because of the signal path from the transmitter being obstructed by trees, this can result in the signal level received not being that terribly far above the cut off point for reception known as the "digital cliff", whereby any further reductions in strength no matter how slight can cause reception to drop out.
You can verify this for yourself by carrying out a signal test on the channel you are viewing when the reception is OK and making a note of the strength / quality seen, do it on a few programmes such as BBC / ITV1 / ITV3 / Pick TV (11) / Yesterday (12) as that covers all muxes except HD, then the next time you select a programme and it results in a blank screen carry out the signal strength check again on that programme channel, as even although the screen will be blank the signal will still be there but has just dipped under the threshold that your receivers tuner can respond to, and if you compare the strength when its OK to when not, then you can get an idea of the kind of level your TV drops out at, as they are all different and varies from brand to brand.
If by the way the level the signal has dropped to is seen as being reasonably stable, then a booster will always help in that type of situation by lifting the level further away from the cut off point.
I lost all BBC channels since around 19 June, but all other non-BBC channels are perfect. The transmitters are all working normally--Knockmore and Durris. Local tvaerial technicians believe that the amplifiers installed for roof aerial in the past (when analoguesignal was still on) make signal too strong, because BBC has increase power (full power) on digital signals, and that signals sent from the two transmitters are interfering with each other at my location. As a result, all BBC channels are gone. Freesat is recommended. While I am considering Freesat, I just don't understand why too strong signals can cause no reception. Is it a possible case for two transmitters causing interference? Anyone can help me for that?
tim: There are two points to mention with regard to the aerial technician's advice. Firstly, if you receive a very strong signal, or use an amplifier to create one, it is possible to overload the tuner so that it does not see the the required mux, rather like how much a human eye can see with a very bright light shining at it. The second point, regarding interference between signals from Knock More and those from Durris is caused by the the current frequency allocation which puts the COM muxes from Durris on the same frequencies as the PSB muxes from Knock More. Although the two transmitters are roughly at right-angles at your location it is possible that a reflection of the Durris signal is being received. It could also be that trees in the path of the Knock More signal have reduced the level of PSB1 to the point that it no longer drowns out the much lower strength, unwanted signal from Durris. Looking at the predicted reception at your location, it is suggested that you might also be able to receive the PSB muxes from Rumster Forest. This would involve the use of two aerials, diplexed to receive the COM muxes from Knock More for a full set of channels. It is interesting to note that if more spectrum is released for 4G, the frequency arrangement would change, removing the clash between PSB and COM muxes.
KMJ,Derby: Thank you very much for your explanation. It is true that sometimes the predicted reception says I can get signals from Rumster Forest and Durris. It is only recently BBC indicates that Knock More and Durris are the two transmitters for my location. Interestingly, just about the same time I lost BBC signals, a small woods half a mile away was felled. I suppose those trees were blocking the unwanted signals for many years until now? Would that be a reason? Technicians did mention about 4G spectrum in feature saying that Freeview users might need to install a filter before being able to watch tv. It looks like Freesat or Sky would be the options for me. Pity some of the channels are not available on Freesat, such as Yesterday. Anyway, thanks again for your help. It is much appreciated.