The Digital UK postcode checker is based on the UK television coverage model. The UK planning organisations (BBC, Arqiva and Ofcom) use a statistical model (the UK Planning Model) that is based on a set of assumptions, as is the case for all coverage prediction tools. The prediction model is agreed by the UK planners and is highly tailored to the UK, making it probably the most advanced broadcast prediction tool in the world.
The model has improved greatly in resolution and prediction accuracy over the years as computing power and affordable terrain data has become available. This has increased the resolution of reception prediction. Predictions used to be made to 1km squares, whereas today the model predicts to a resolution of 100m squares (pixels).
Even though the model works to a high geographical resolution, it must be noted that the model cannot take into account factors such as - buildings, other than a general allowance for "clutter"; trees or individual receiving circumstances.
The detailed view provides comprehensive details of television reception options for an address or postcode based on the nearest prediction point to either the address or postcode centroid. The DTT predictions are those which are used to plan and protect the DTT network, and the prediction is based on the assumption that a consumer uses a representative receiving system in good condition with the aerial at 10 metres above ground level. Predictions can vary significantly over a short distance due to the effects of terrain and interference, so they should be treated as a guide to the likely situation on the ground.
The checker does not currently include information about the small number of Community Self-Help transmitters.
The 'most likely' transmitter indication is provided to us by the BBC. It is derived from a complex algorithm which takes into account, among other things:
The 'most likely' transmitter is not a recommendation. It is a best estimate of the transmitter that a viewer is likely to be using to receive their terrestrial television. We need to derive this because the likely viewing experience, addition of new services and dates of any changes to reception quality are driven by the transmitter being used. If a viewer knows that they are using a different transmitter, they can select it from the drop-down box, and the results will be refreshed accordingly.
Information relating to the digital transmitters which are predicted to be receivable at the search address:
The 'most likely' transmitter to be in use. This will usually be the same as the historic 'most likely' analogue transmitter, providing that transmitter continues to provide coverage.
The distance to and bearing of the transmitter from the address.
The digital aerial group and polarisation a) now b) after any future changes.
The Prediction section details the transmission channels and a multiplex-by-multiplex coverage prediction for each transmitter that is predicted to provide a usable signal (i.e. a prediction of at least 50) on at least one multiplex at the address or postcode centroid at any time. The prediction is repeated for each step where there is a change in either coverage, or transmission channels.
Two predictions are provided:
The higher the prediction figure, the better the reception margin.
The prediction is made at an undetermined point (determined by the prediction algorithm) within a 100m x 100m tile. Based on the use of an antenna of the correct type at 10m above ground level, the signal is predicted to be receivable without interference from co- and adjacent-channel transmissions for at least 99% of the time to the proportion of the tile indicated, measured in %. The UK planning standard is met where at least 70% of the tile is served in this way, i.e. for values between 70 and 100.
The prediction is made within each 100m x 100m tile. Based on the use of an antenna of the correct type at 10m above ground level, the signal is predicted to be receivable without interference from co- and adjacent-channel transmissions for between 50% and 99% of the time to the proportion of the tile indicated, measured in %. While this does not meet the UK planning standard for service reliability, the level signal may be usable and the level of service acceptable to a consumer.
Information relating to the current availability of other digital television platforms in the postcode, as provided to Digital UK by the relevant platform provider. Note that in general, predictions of future coverage are not available. The limitations of cable and DSL network coverage means that availability to a specific address needs to be confirmed with the relevant platform provider.