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Types of Broadcasting
Published in Skip Pizzi, Graham A. Jones, A Broadcast Engineering Tutorial for Non-Engineers, 2014
DRM stands for Digital Radio Mondiale, a system developed primarily as a direct replacement for AM international broadcasting in the shortwave band, although DRM can also be used in the medium wave and long wave bands. DRM uses the same channel plan as the analog services, and, with some restrictions and changes to the analog service, a DRM broadcast can share the same channel with an analog station. DRM is a monaural (single audio channel) system when used with existing channel allocations, but stereo (two-channel) audio may be possible in the future, if wider broadcast channels are available. DRM started trial implementations in several countries in 2003 and is now in regular use by a number of major broadcasters around the world, primarily in Europe and India. The DRM receiver marketplace remains limited at this writing, however, and consumer uptake has not been particularly robust to date.
IBOC Digital Radio and the State of the Digital Radio Industry
Published in David P. Maxson, The IBOC Handbook, 2007
DRM is an acronym for the digital audio broadcasting scheme from Digital Radio Mondiale, the name of the consortium that developed it. The DRM consortium was formed in 1998 to define a new digital audio system aimed at designing a system to facilitate conversion of analog services to digital for the bands below 30 MHz. DRM is an international standard for digital transmission on short-wave, medium-wave (which includes AM broadcasting) and long-wave frequency bands. In addition to being standardized for these bands below 30 MHz, in 2005 the DRM Consortium began the process of extending the system up to 120 MHz, with completion expected between 2007 and 2009.
Storage and transmission of spatial sound signals
Published in Bosun Xie, Spatial Sound, 2023
DRM retains the existing bandwidth and frequency planning for analog AM broadcasting. After some revisions, the existing AM transmitter can be used for DRM, which facilitates a transition from analog to digital broadcasting.
The Changing Face of Public Broadcasting in India
Published in IETE Journal of Education, 2023
DRM [1] is a revolutionary technique, which can provide high quality sound from standard AM channels, and can cope up with fading and ambient noise. India has started expanding its radio network with DRM. It uses coded orthogonal frequency division multiplexing (COFDM) with quadrature amplitude modulation to transmit digitized and data compressed audio signals. The process of data compression and coding is defined as per DRM30 standard, and the bandwidth requirement is substantially reduced. The digital audio signal modulates a subcarrier of 12 KHz. This modulated subcarrier is linearly added to the primary audio, which has been band limited to 5 KHz. This multiplex, in turn, is used to amplitude modulate the carrier frequency in the MW or SW wave band. Thus a single carrier at RF can transmit both AM double sideband (AM DSB) as well DRM subcarrier on a single channel [2]. The reception of DRM signals requires radio receivers specifically designed for decoding digitally modulated signals. At the receiving end, a 12 KHz band pass filter is used to separate the DRM signal, and a 5 KHz low pass filter to recover the regular AM signal, post demodulation. The DRM section would require a set of filters, and use digital signal processing (DSP). It has now become possible to implement DSP in a small space inside a receiver. Block diagram of a typical DRM receiver has been given in Figure 1.