BBC/Ofcom DAB In-home Reception Trial
Following the 2009 Digital Britain report, the Government published a Digital Radio Action Plan for a potential switchover of key services from analogue to digital radio. It concluded that a decision could only be made once certain criteria had been fulfilled, including when national DAB coverage is comparable to FM, and local DAB reaches 90% of the population. These coverage criteria relate to both outdoor and indoor reception. Indoor reception is inherently more difficult to predict due to variability in building types and construction.
To help develop a more accurate view of DAB indoor coverage the BBC and Ofcom agreed to jointly manage a research project in 2013 which would measure DAB reception in households across a variety of different coverage areas. This would enable the software-based model which is used to predict DAB coverage, to be validated, or if necessary, refined. Reception was tested in a number of different locations within a large number of homes and the results compared with predictions made by the model.
Specifically, the project obtained DAB reception measurements within households located in a number of pre-selected coverage areas in order to determine how well the model’s predicted level of coverage matched measured levels of coverage. The location and number of areas, which were selected to have a wide range of multiplex signal levels, were mutually agreed by Ofcom/BBC.
Measurements were conducted in two phases, the first in 1200 homes and the second, which introduced an additional test of directly substituting a DAB radio for the main household FM radio, in an additional 504 homes.
DAB services are delivered by a small number of multiplexes, each carrying around 10 stations. In the initial phase of work the majority of homes predicted to have reception did so while a small number had little or no reception of one or more multiplexes. To gain more insight into this issue, the BBC and Ofcom agreed that a further phase of in-home testing trial was required which focused on investigating the accuracy of the model as the coverage tends towards 100% in relation to how it compares to consumers' current reception and use of FM radio. No evidence of a systematic error was found in this second phase of measurement.
The findings of the two phases of this study confirm that
- on average the Prediction Model gives a good indication of the level of DAB coverage and
- DAB reception in ‘good’ DAB coverage areas is equivalent to good FM reception