What is the spectrum occupancy of a single programme using DRM?
With DRM30 the spectrum occupancy of a single programme is between 4.5 kHz and 20 kHz depending on the mode. Besides the single channel bandwidth options of 9 and 10 kHz spectrum occupancy, DRM30 also supports half (4.5/5 kHz) and double (18/20 kHz) channel options. Clearly the mode has to be chosen to suit the amount of spectrum available. Also, the audio quality of the transmitted signal will increase as the bandwidth increases. Particularly using the higher bandwidth modes it is possible to fit two or more audio programmes into the DRM30 signal. The bandwidth of the DRM+ signal is fixed at 100 kHz. Within this is it possible to transmit up to 4 stereo audio programmes. Clearly there will be a trade off between audio quality and the number of programmes multiplexed together. However in its most ‘frugal’ mode the ‘effective bandwidth’ occupied by a single audio programme is 25 kHz. In general there is a high degree of correlation between the left and right hand channels of stereo audi
