RFmondial tests DAB+ disaster rebroadcasting

RFmondial has successfully conducted a field test in Hanover under real conditions to trial alternative distribution solutions to DAB+ transmitters in the event of a disaster. 

Broadcast coverage is an essential building block for citizen information during disasters or dramatic events since mobile phone networks are usually the first to fail. An alternative distribution is, therefore, critical to ensure coverage reliability in the case of standard link failure, such as that of land-based lines in the event of flooding or satellite reception during storms. 

For this purpose, RFmondial has developed a system that uses the regular air interface for distribution — so-called rebroadcasting. DAB+ transmitters unable to receive their standard link receive programming over the air from another DAB+ transmitter, then convert it to a different frequency and retransmit it with a short delay. The signal is then received by other DAB+ transmitters and broadcast again on a different frequency. This process guarantees nationwide broadcasting coverage even in the event of a disaster. In addition, a data channel hidden in the DAB+ broadcast can control and maintain the transmitters. 

In the Hanover test, performed in conjunction with transmitter manufacturer Plisch, a DAB+ transmitter (channel 5A) in Hanover Hemmingen served as the primary network transmitter, and another DAB+ transmitter (channel 7C) in Hanover Nordstadt served as a transmitter in rebroadcasting mode, creating a multiple frequency network (MFN). The test also examined the suitability of DAB+ receivers for service following — switching to a changed transmission frequency — and provided manufacturers of consumer and automotive receivers the opportunity to test and, in some cases, improve their receivers for rebroadcasting.

Those interested in more technical details about the test may contact RFmodial.