Wave Propagation and Field-Strength Predictions
Predictions of coverage are essential for planning and preserving terrestrial broadcasting services. A prediction identifies a geographical area or a segment of the population which is considered to be covered by a transmitter network. In addition to the analysis, additional data are generated concerning aspects of coverage.
Predictions of coverage combine several components to provide reliable conclusions: a set of transmission data, wave-propagation models, the accumulation method, the synchronisation method, the protection-ratio method, reception scenarios and/or the Geographical Information System (GIS module). IRT relies on different experienced specialists for each of these approaches.
Long-Term Measurements of Propagation Parameters
Data, such as received field strengths of various VHF and TV transmitters, must be gathered over a long period of time in order to improve predictions of brief intervals (interference). This is the only way to obtain statistically relevant information about short periods of time.
Wave Propagation
IRT has developed a large array of prediction methods; the proper model can be selected for any given task. IRT’s 3-D model delivers especially precise field-strength predictions since it considers digital terrain models, orographical data and explicit multipath propagation.
Investigating Single Frequency Networks for Digital Broadcasting Services
In order to analyse coverage areas and identify fringe areas, IRT experts rely on the “accumulation method” and the “synchronisation method” to investigate single frequency networks (SFNs) in the case of digital broadcasting services. Both of these methods represent a variety of coverage-analysis techniques which IRT had a leading role in creating. One example of our expertise in this field is FRANSY: frequency-planning software which enables the user to create predictions of coverage via an intuitive interface.
Ongoing research aids our staff in optimising existing prediction techniques and developing new methods so that we can respond appropriately to the needs of the dynamic field of frequency management.
Conducting Field Tests on Broadcasting Systems
The design of transmitter networks for new broadcasting systems presupposes predictable reception parameters at reception points. Propagation models are therefore developed, which in conjunction with terrain data constitute a realistic basis for the planning of broadcasting coverage.
IRT utilises a specialised test vehicle to determine broadcasting coverage as well as various propagation parameters of transmission channels and transmitter networks (e.g. DAB, DRM and DVB-T). Our test vehicle enables us – in the experimental stage – to reliably evaluate the transmission quality of broadcasting systems and detect any malfunctions.
Image Copyright: Kathrein Werke, Rammel
