Reception problems after switchover

We have explained elsewhere on this site why digital terrestrial ('Freeview') signals cannot provide full coverage in a particular region until digital switchover has been completed in the region. But we are now hearing a number of stories from regions where switchover has been completed and yet, for some people, problems persist.

It has to be said that there are one or two issues which are systemic, that is to say there are problems which are known to exist in certain areas and are not exactly the fault of individuals' own equipment...

The most widespread problem so far is in parts of NW England where viewers' aerials and digital receivers are now picking up signals from two different high powered main stations, namely Winter Hill (for Lancs. and NW England) and Moel-y-Parc (for NE Wales). The problem here, for viewers in England is that digital receivers are tuning in the Welsh station first and favouring it over the English one. There are ways around this problem but it was made worse by Digital UK being slow to pick up on it and give people constructive advice.

There has also been a more localised problem in parts of Ilfracombe in North Devon, where local signals now suffer interference from the transmitter which serves the Swansea area.

These issues aside, there are also a significant number of individuals who are still having problems with their reception in post-DSO areas where good reception should now be more-or-less guaranteed. The usual complaints are of picture or sound break-up. In such cases the blame almost certainly lies with the individuals' own aerial systems.

People who previously thought they had "good" analogue pictures are usually quick to blame the broadcasters and slow to look critically at their own set-ups, but we have identified a number of issues which should be considered by those still suffering poor reception after switchover.

The first thing to say is that, technically, the new high-powered digital transmissions are more 'complex' than the low-powered ones, and they require the set-top boxes to work harder than before. It's become clear that aside from those set-top boxes known not to work at all after switchover it is also possible that others make the transition from the old (2k) signal format to the new (8k) format unsuccessfully by working, but just not well enough. Your writer's first set-top box - an early Grundig - fell into this category and had to be retired. Therefore our first suggestion would be to see if you can borrow a set-top box which is known to be working well and try it on your aerial.

Note: It is most likely that a set-top-box borrowed from a neighbour will work on your aerial without needing to be re-tuned, but we suggest performing a re-tune from the receiver's Setup or Installation menu whenever it is moved to a new location.

If an alternative box works well on your aerial then it's time to throw out your old box and replace it with a new one - it needn't be an expensive one, just a new one. Some of the cheaper boxes found in high street chains and supermarkets are surprisingly good. (You should also consider, at this point, whether you need a box with a built-in recording ability.)

Tests carried out on a range of boxes involved running them from weak signals, strong signals, and signals suffering disturbance by wind turbines. No significant difference
was found in the performance of these boxes, and certainly no price/quality correlation. When
considering things like the friendliness of the remote though, there was a price/quality correlation.

If a known good box behaves badly on your aerial then of course it is timeto face facts and admit that however good your old analogue pictures may have been, your aerial system needs attention, so let's go through the possibilities... what makes an aerial which gave good analogue reception give poor digital reception?

It could be something very simple...

Before you do anything else, try to analyse when these picture and sound break-ups happen. Can they possibly be related to things happening near or actually inside your house...?

Does the picture or sound break-up when

• lights in the house are turned on or off
• the central heating boiler or pump starts or stops
• the 'fridge or freezer starts or stops
• when cars drive past
• after damp/rainy weather?

If you can relate the problem to anything like this then the cable between your aerial and receiver almost certainly needs replacing.

Clue: If your old analogue reception suffered from flashes or speckles you could have got used to that type of 'impulse' interference, but digital receivers find that very hard to cope with.

Next, let's look behind your tv and see what's going on... does the aerial cable go straight to the back of the receiver with no plugs, sockets or joins? If not, here's the next thing to try: a new aerial fly-lead. The fly-lead is the cable - usually short and white - which connectsyour receiver to the aerial socket on the wall. Digital equipment generates a fair amount of electrical disturbance and if you have a cheap, poorly screened aerial fly-lead it can pick up interference. Put simply, you could be letting your receiver interfere with itself. (Or should I rephrase that? No, let's move on quickly...) This type of problem wasn't really an issue with analogue, but with digital it is.

Try a new fly-lead, and don't shop around or buy a cheap one from that man with a market stall, get a good one from a reputable dealer. On the other hand there is no need to go for anything fancy, gold-plated or expensive. (Somewhere around £3 - £5 would be about right.) Ideally you should ask a small trader (a local shop or aerial firm) to make you a flylead using metal bodied plugs and ‘double screened’ cable (also known as ‘satellite cable’).

Secondly, is the plug loose in the wallplate? Can the plug move the socket in the wallplate freely if you wiggle it? If so the connections inside the wallplate are very probably broken.

A contractor recently went to a house where an elderly couple had just moved in. The house had a satellite dish and 'no aerial' according to the outgoing residents, so they had been asked to fit an aerial for Freeview. They examined the rats-nest of cables in the corner behind the tv and found no less than three aerial cables present. These were unravelled and each plugged, in turn, into the digital tv. Two gave no result but the third brought in most of the Freeview signals. A quick head count revealed that five of the six digital multiplexes were rock-solid but a sixth gave pictures and sound which were intermittent and stuttering. This was not surprising given that there was a nasty twisted join in the cable which was held together with old insulating tape. Perhaps this arrangement had been satisfactory for four analogue tv signals? We will never know! The joint was pulled apart and replaced with a proper coaxial socket mounted on the skirting board, then a good quality fly-lead was used to connect the receiver to the new socket. This fixed the problem with the dodgy multiplex and far from needing a whole new aerial system the customer only had to pay for a socket and a fly-lead, plus a little of their time. The customers were delighted and the contractor moved on swiftly to the next job.

Now, while we're looking at the back of the set is there any kind of aerial splitter or booster in use? If so, try connecting your digital receiver directly to the aerial and put any aerial spliiting amplifier after the digital receiver. Also experiment with the gain if the amp has a variable gain setting.

The simpler the path from the aerial to the receiver the better. The key here is that if digital receivers are fed with a good, clean signal they don't actually need a lot of it. In other words, it's quality that counts, not quantity. That's why aerial amplifiers that simply fit behind the TV set are usually no help, so don't buy one from someone trying to tell you it will solve all your problems - it's not likely to.

Now, has removing all this superfluous electrickery solved your problem? Hopefully so, but if not then your only recourse is to employ the services of a good local aerial contractor. In most cases replacing the aerial downlead with good quality (CT100) co-axial cable will solve most interference problems but if your aerial is old and possibley corroded then replacing the arial is also a good idea. Aerial cable which has poor joins in it or starts becoming susceptible to damp can do strange things, sometimes exhibiting poor performance on just one or two specific frequencies and affecting specific groups of digital channels. Exposed to the elements these things can't be expected to last forever.

We hope you can see, from this short article, that we have shown a few issues which probably would never affect analogue reception but which can easily give rise to problems in the brave new digital world.

In the old days we could put up an aerial, look at the picture and know instantly where we were and if we had problems. Those days are going, going, gone - but experience and common sense backed up by good test equipment, will still get us where we need to be.

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