Analogue transmitters
Information relating to the analogue transmitters which could potentially be in use at the address are listed:
- The 'most likely' transmitter to be in use, derived from a complex algorithm. Note that this may not be the transmitter in use, and it is not always possible to identify a most likely transmitter.
- The distance to and bearing of the transmitter from the address
- The transmission channels, listed in the order BBC One, BBC Two, ITV1, C4/S4C and C5.
- The analogue aerial group and polarisation
Digital transmitters
Information relating to the digital transmitters which are, or are likely to be, receivable at the search address:
- The 'most likely' transmitter to be in use. This will be the same as the 'most likely' analogue transmitter, providing that transmitter provides coverage after switchover.
- The distance to and bearing of the transmitter from the address
- The published switchover date
- The digital aerial group and polarisation a) now b) after switchover
Coverage prediction
The coverage prediction section gives a multiplex-by-multiplex view of the transmission channel and reception prediction for each transmitter that is expected 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 during the switchover process. The prediction is repeated each time the switchover process gives rise to a change in transmission channel or the reception prediction changes significantly.
Two reception predictions are provided for each multiplex:
- Likelihood that the signal is protected against interference for at least 99% of the time - "Served"
- Likelihood that the signal is protected against interference for at least 50% of the time - "Marginal"
The higher the prediction figure, the better the reception margin and hence protection against interference.
A multiplex will be flagged as green where the "Served" prediction is at least 70, which is the threshold for the reception of a multiplex to be considered sufficiently reliable to qualify as a service.
A multiplex will be flagged as amber where the "Served" prediction is less than 70, but the "Marginal" prediction is at least 70. In this situation there is sufficient signal to receive the multiplex, but reception is likely to be subject to periodic interference from other more distant transmitters on the same channel. A decision can be made as to whether this reduced quality of service will be acceptable to the customer.
A multiplex will be flagged as red where the "Marginal" prediction is at least 50 but less than 70. In this situation the multiplex may be received, but reception is likely to be subject to significant periods of interference from other transmitters on the same channel. It is unlikely that the quality of service would be acceptable for the majority of customers.
Other platforms
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.
How to interpret the Trade view of the Postcode Checker
The Trade view provides comprehensive details of television reception options for an address or postcode based on the nearest prediction point to the address or postcode centroid. The DTT predictions are those which are being used to plan the DTT network, and assume a representative receiving system in good condition. 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 include information about self-help transmitters.