Freeview viewers experiencing reception problems, pixelization or missing channels, should check the following:
- Check for temporary transmitter faults or planned maintenance, for details of planned engineering works that may be affecting your reception:
www.digitaluk.co.uk/engineeringworks - Check the BBC website to find out if faults or maintenance are affecting BBC transmissions in your area:
Freevew Reception Advice - If other residents in your area are experiencing problems, this is a good indication that a transmitter fault may be to blame.
- Retune your TV and check that your cables and connections are not faulty.
- Try unplugging your TV and then retuning it once the connection to the power has been restored.
- Check your cables, are they worn or damaged? Coaxial cable outdoors can deteriorate, become damaged or affected by the rain, frost or snow over time.
- Find out if there is a problem with your aerial, heaving winds can damage or mis-align outdoor aerials.
Missing channels
If you are missing channels, try retuning your digital box or Freeview TV. Channels on Freeview also change from time to time – new ones are added, some are removed and others move to different channel numbers or multiplexes. It’s worth retuning every so often to make sure you’re up to date.
After retuning, if channels are still missing:
There may be a software problem, so try turning your TV or box off at the mains and then restart (reboot).
Check your available transmitters and channel list on the coverage checker located on the DUK website. If all the channels in one of these multiplexes are missing, the problem may be in your aerial.
If you can receive some of the channels in a multiplex but not all, the problem is more likely to be on your TV. Please contact your retailer or the equipment’s manufacturer.
Retuning
A full retune should only take a few minutes and can be done using the remote control.
Make sure your Freeview TV is on and then press ‘Menu’.
- Select the ‘set up’ or ‘installation’ option. If you see picture icons, select the toolbox or spanner. If you are prompted for a code, try 0000 or 1234.
- Select the full retune option. This is sometimes called ‘first-time installation’, ‘factory reset’, ‘default settings’ or ‘shipping conditions’. Do not select ‘channel update’ or ‘add channels’.
- Press ‘OK’ if your equipment asks if you want to delete all your channels, all current TV and radio channels will be deleted.
- Channels will automatically be installed. This may take a few minutes and your equipment may shut down and restart.
- Depending on your TV equipment, you may need to update your favourites list following a retune. Some digital recorders may require scheduled recordings to be reset.
In some cases, where transmitter signals overlap, it may be necessary to carry out a manual retune.
A manual retune lets you select the correct transmitter and regional TV services for your address.
Aeriel Groups
Freeview is broadcast in the UHF band between 21 and 68, aerials are designed to receive certain parts of the UHF band, and an aerial will have a “Group” letter to represent which part of the band it covers. Selecting the correct aerial group could prevent interference from transmitters outside your area
Terrestrial TV aerials are split into the following groups:
Group A – Channels 21-37
Group B – Channels 35-53
Group C/D – Channels 48-68
Group E – Channels 35-68
Group K – Channels 21-48
Group W – Channels 21-68 (Wideband)
A Group W aerial can be used anywhere in the UK as they cover the whole of the UHF band. In areas prone to poor Freeview coverage, a wideband aerial may not be as effective as a high-gain aerial from the correct aerial group for your area. If you are in a ‘Freeview Lite’ area (reception of only the PSB multiplexes), then it could be an option to have more than one aerial, one for the PSB multiplexes using the correct aerial group and a second high-gain aerial for commercial multiplexes from further afield, again using the correct aerial group for the transmitter.
Communal Aerials
If you share a communal aerial (for example, in a block of flats) and you are having reception problems, the aerial may be faulty. See if other residents using the same aerial have the same problem.
If there is still no improvement, your aerial may be broken or out of alignment. If you can see your external aerial, look at whether it is pointing in the same direction as others nearby.
You should have the aerial and its connections checked for faults.
Signal Amplifiers
Signal amplifiers are mains-powered units that amplify the received signal. These can be useful if you are in a weak signal area, they are also useful if you want to feed a single to more than one TV or set-top box. The amplified difference between the input and output signals is known as the Gain of the amplifier. Gain is basically a measure of how much an amplifier “amplifies” the input signal.
Remember that long cable runs will reduce signal, a signal amplifier can be invaluable in keeping that loss to a minimum. Signal amplifiers are available with 1, 2, 3, 4, 6 and 8 outputs,.
Of course, the best way to increase and improve signal strength is to use a high gain roof-top aerial. Make sure this is suitable for your location, with the correct aerial group, correct number of elements and positioned at high as possible without any physical obstructions.
Masthead amplifiers (MHA) or distribution amplifiers—often called ‘signal boosters’—are not an integral part of, ‘optimised television receiving installation’. They should be installed only if necessary. These kinds of devices can cause reception difficulties and even interfere.
An MHA—or ‘booster’—should only be used in areas where television signals are very weak because of intervening terrain, vegetation and buildings, or due to the distance between the transmitter site and television antenna. An MHA is typically installed next to your TV antenna.
A distribution amplifier is used to distribute the signal to more than one TV. Unlike an MHA, a distribution amplifier is installed within the building in which it operates, normally within the roof area. Distribution amplifiers can be used in houses with multiple TV sets, hotels, motels, blocks of units and similar high-occupancy buildings.
Bit Error Rate (BER)
In digital transmission, the number of bit errors is the number of received bits of a data stream over a communication channel that have been altered due to noise, interference, distortion or bit synchronization errors.
The bit error rate or bit error ratio (BER) is the number of bit errors divided by the total number of transferred bits during a studied time interval. BER is a unitless performance measure, often expressed as a percentage.
The bit error probability pe is the expectation value of the BER. The BER can be considered as an approximate estimate of the bit error probability. This estimate is accurate for a long time interval and a high number of bit errors.
Forward Error Correction (FEC)
Forward Error Correction (FEC) is a technique used for controlling errors in data transmission, FEC is accomplished by adding redundancy to the transmitted information using a predetermined algorithm. Part of the data stream is used solely to correct errors in the downlink stream from the satellite. This prevents the picture breaking up.
A FEC of 2/3 means that every third bit of data is used to correct errors in the previous two bits. Here signal would be more robust and can be received easier, with less breakup in rain, for example. It is less efficient, with not so much data available to transmit the picture.
A FEC of 9/10 means that just one-tenth of the data is used to correct errors, making the signal harder to receive and much less robust. It will break up more easily in weak signal areas, or when subjected to interference. For the broadcaster, 9/10 means that more channels can be squeezed in, at a higher data rate.
The difference between FEC 2/3 and FEC 9/10 is that an extra 4.5dB ES/No is required to stay above the threshold. Currently, most UK PSBs use a FEC of 5/6, which is not very robust in fringe areas.
The Digital Cliff
In the days of analogue TV, reception was possible to varying degrees depending upon your location, though you nearly always managed some kind of reception.
Digital TV is quite different, this is known as the “Digital Cliff Effect”. This is when the video data falls so low (below the threshold) of visible picture information. Reception is either accomplished successfully or it is not, there is no in between.
You may see a frozen picture, nothing at all heavy pixelisation with gargled sound or clicking.
On Freeview, this cliff effect is most often experienced in rural or mountainous areas and in cities with large buildings, as well as the fringes of local stations coverage areas,
Forward Error Correction (FEC) is often used to address the problem when a minimum threshold of signal quality (a maximum bit error rate) is reached, there is not enough data for the TV’s tuner to recover. This often causes the picture to break up (pixellation), lock on a freeze frame, or go blank. Causes include rain fade, temperature changes or other weather or atmospheric conditions.
A TV with a good receiver (low threshold) could make all the difference in maintaining stable reception. The lower the tuners threshold, the lower the signal level required to produce a picture on the TV.
Freeview Lite
What is referred to as ‘Freeview Lite’, is actually the three PSB multiplexes, PSB 1 operated by the BBC, PSB2 operated by ITV plc and Channel 4 and PSB3 operated by the BBC.
PSB3 transmits in DVB-T2 and contains simulcasts of the PSB channels in HD.
These three Public Service multiplexes are obliged by their public service status to reach 98% of the UK population, this is in contrast to commercial multiplexes which have no such obligation and broadcast where it is considered commercially viable. It is up to the individual operators to decide whether or not their mux should be made available to rural areas via relay transmitters.
Most affected, are northern and central Wales, the Scottish Highland and islands, parts of England, the Isle of Man and the Channel Islands.
This could change in the future, as multiplexes migrate to DVB-T2 and PSB standard channels are replaced with HD versions.
An aerial upgrade could also be an option in some areas, allowing reception of the commercial muxes.
Viewers with limited or poor Freeview reception can receive most Freeview channels, though not all on satellite.
Interactive services (BBC Red Button)
If you have been having problems accessing the BBC Red Button service on Freeview you may need to re-tune your Freeview TV or box. problems are often caused by either the TV’s software or by weak signals.
First, try restarting your TV, then check your aerial cables and then your aerial if necessary.
The BBC run two interactive television services – BBC Red Button, an interactive service for digital TV and BBC Red Button+ – available on some Internet-connected TVs.
Available on some Internet-connected TVs, Red Button+ combines the delights of traditional telly and interactive internet, all in the simplest way possible.
BBC Red Button+ brings you the best of BBC Online and iPlayer straight to your living room. You can access the service by pressing the red button on your remote control and enjoy additional content from BBC TV, News, Sport, Weather and CBBC and CBeebies.
Channels from the wrong BBC/ITV region
If your area is covered by more than one digital transmitter group, you may pick up signals from the wrong region. Make sure your aerial is in good condition and pointing towards the correct transmitter for your area.
Firstly, you will need to delete all existing installed channels from your TV, set-top box or PVR. This will remove unwanted channels from the different region/s, which are stored in memory.
The tuning menu for TVs or Set Top Boxes can usually be found under “Setup” > “Installation” or there might be a spanner on-screen icon when you press “Menu” on the remote.
If a password is required to access the Installation menu – try “0000” or “1234” as these are the normal defaults.
To re-install Freeview channels for the correct region, you will need to do a “manual tune” or “manual installation” and enter the UHF channel number of each local transmitter multiplex in turn.
4G & 800 MHz Clearance
Mobile operators are rolling out 4G mobile services across the UK. 4G enables mobile devices such as smartphones, laptops and tablet PCs to access the internet at super-fast speeds.
The 800 MHz frequencies used by some 4G services are next to the frequencies used for Freeview. There is a small chance this may cause disruption to Freeview services.
The first 4G at 800 MHz services launched on 29 August 2013. These networks are now expanding across the UK; when and where they will launch depends on the rollout plans of the mobile operators.
For more information on when they will be available where you are, visit coverage checkers on the operators’ websites.
at800 Filters
at800 domestic/household filters are small boxes which block 4G at 800 MHz signals and in most cases enable you to carry on receiving watching Freeview as normal.
The filter needs no batteries or external power supply. It will normally plug into the lead between the TV and the aerial. If you have a TV signal amplifier or booster, the filter must be fitted between the aerial and amplifier.
at800 is an independent organisation created to ensure that all UK viewers continue to receive Freeview, or are offered a suitable alternative when 4G at 800 MHz is activated in their area.
Website: https://at800.tv
Resources
Aerials (A.T.V. Poles, Brackets & Aerials)
A Buying Guide for Freeview Aerials (eBay)
Freeview Reception – Help and Advice (Radio & Telly)
Reception guide (Digital UK)
