German public broadcasters launch sparse image audio service trial
Monday, August 20th, 2007

A sparse image audio service trial has been launched by German public broadcasters WDR in Cologne and MDR in Leipzig. In the area of greater Cologne, the proposed broadcasting location is the Klnturm (Cologne tower) in Mediapark with an aerial height of 160 metres. The DMB multiplex is on channel 11D, and the radiated power of 10 Kilowatts is aimed at in-house coverage for Cologne city centre.

During the trial, broadcasts consist of existing TV programmes as well as visually enhanced radio programmes - for example displaying the CD cover of the track being played or a road map with traffic news. The DAB/DMB technology employed was developed in co-operation with the Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute (HHI) in Berlin. Instead of the usual DAB format, however, a High Efficiency Advanced Audio Coding HE-AAC radio format is being used. This reduces the bandwidth of 192 Kilobits per second to 48 Kilobits per second.

To save bandwidth when broadcasting images, the images are compressed using a technology which was developed for mobile phone television. When a new image is broadcast every two seconds, this only adds 10 to 15 Kilobits per second in bandwidth. The scientists at HHI were also pivotal in the development of this currently most efficient video encoding format called H.264/AVC.

(Source: Heise Online)