DRM+ trial in Brazil
The technical support and equipment for the trial in Brazil was provided by RFmondial, Fraunhofer, Nautel and the University of Hannover who set up the equipment.
The test demonstrated a very low power simulcast setup with a DRM+ 4W transmitter alongside a 25W FM transmitter, both with quite a low antenna. Community radios in Brazil are only permitted to cover a radius of 1 km. In addition to the live program of Líder FM, text messages and the News service Journaline were also transmitted.
Good reception was achieved over an area up to 1.5 km from the transmitter, and in one direction, on a nearby hill, it was received as far as 4 km away. This coverage was in contrast to the FM signal, which suffered greatly from interference from a neighbouring FM transmitter broadcasting on the same frequency. The DRM digital signal was not affected by interference because the digital frequency can be assigned flexibly to either side of the FM or to somewhere else in the spectrum. Through careful planning , neighbouring digital stations can use the frequencies on either side of the analogue signal to avoid interference. Further analysis during the test also proved that there was no audible effect to the FM quality when the digital signal was switched on and off.
Friederike Maier, University of Hannover
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