Digital Radio (DRM+) with innovative transmiter concepts
The project „Digital Radio (DRM+) with innovative transmiter concepts“ is promoted by the foundation "Future and Innovation Foundation of Lower Saxony" (Zukunfts- und Innovationsfonds Niedersachsen).
Due to the worldwide digitalisation of radio broadcasting in the last years, innovative technical solutions are essensial to meet the requirements of broadcasting operators, receivers, producers as well as political aspects. The DRM+ (Digital Radio Mondiale Mode E) is the most likely potential candidate to replace the world wide 36.000 operating radio stations and 3 billion radio receivers .
The objective of this project is to enhance the technical headstart by development and test operation of innovative DRM+ transmitter concepts (transmitter diversity, common-wave operation) under real conditions. These works have been done within the coorperation with the radio provider Antenna Lower Saxony ( Antenne Niedersachsen), radio ffn as well as with the radio broadcasting producer RFmondial GmbH. The developed concepts serve the purpose to expand the economical, regulatory and qualitative advantages of the DRM+ technology.
The Media Authority of Lower Saxony (Niedersächsische Landesmedienanstalt - NLM) supports this project in respect of radio technology, juridical as well as regulatory framework.
The DRM+ system on the basis of OFDM (Orthogonal Frequency Division Multiplex) is capable to compensate the variation of the signal amplitude by interleaving in frequency and time domain and a underlying error-correction. The variation of signal amplitude is caused by the multipath-propagation effect of electromagnetic wave and mobile receivers under real transmission conditions. Around the 100 MHz range and in case of a low rate receiver, the channel diversity could not be sufficient enough, so that a massive signal attenuation over long interval in time and over the entire signal bandwidth can occur due to destructive interference of propagating signals. In order to avoid this effect, the transmitter diversity can be implemented. By applying more than 1 atenna at the transmitter side and transmit the signals delayed in time, additional diversity can be contributed for the entire system.
In common-wave opeation, the digitalized radio signals will be transmitted at the same frequency from several stations located in different places. In this operation mode, each transmitted signal carries exactly the same information. This way, the stations can cover a large service area or work in small areas as secondary stations. Compared with the analog radio broadcasting, the digital signals of different transmitters don’t interfered with each other due to the OFDM modulation. The mutipath-signals rather enhance the radio reception. The fact that common-wave-network operates at the same frequency relieves the radio-network planning and raises the efficiency in term of frequency allocation.