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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.
Digital Audio Broadcasting
Published in Jerry D. Gibson, Mobile Communications Handbook, 2017
Digital Radio Mondiale (DRM) is an international nonprofit consortium for digitization of broadcast (shortwave mediumwave and longwave) up to 30 MHz, DRM30. The DRM consortium is composed of broadcasters, network providers, transmitter and receiver equipment manufacturers, universities and research institutes. DRM+ extends operation to VHF bands up to 174 MHz, [wDRM]. DRM30, includes digital shortwave radio. The consortium was formed in 1998 and the first broadcast took place in 2003. Data Services are also included [wDRM]. Transmission is organized in a number of different modes, including hybrid adjacent modes, [wDRM].
UWB Antennas for Multifunctional Operations
Published in Chinmoy Saha, Jawad Y. Siddiqui, Yahia M.M. Antar, Multifunctional Ultrawideband Antennas, 2019
Chinmoy Saha, Jawad Y. Siddiqui, Yahia M.M. Antar
RF and antenna engineers consider cognitive radio (CR) technology as an evolution and improvement on software-defined radio (SDR). Though the field of SDR and CR is quite versatile and multi-disciplinary, we should have a brief idea on the evolution from conventional fixed spectrum radio operating in FSA mode to modern cognitive radio, working on the principle of dynamic spectrum access. The evolution of modern cognitive radio (CR) can be described by the following stages: Hardwire driven radio (HDR): This is the conventional radio for which the frequency, modulation techniques, and various related RF parameters are solely determined by hardware and cannot be changed without a change in hardware.Digital radio (DR): A digital radio performs signal processing and transmission in full or part using digital techniques. However, it is not programmable and intelligent like a “cognitive” radio.Software-defined radio (SDR): This has evolved due to the necessity to implement radios that can be controlled by programming to reconfigure so that it can be operated over a wide frequency range, various modulation schemes, etc. In this way, SDR can support multiple standard wireless radios.Cognitive radio (CR): Cognitive radio (CR) is an improvement on SDR due to the ability to learn from the observed environment and autonomously reconfigure its hardwire, including antennas and RF circuits, to support the optimal mode of communication. CR can be defined as: “An SDR that is aware of its environment, internal state, and location and can autonomously adjust its operations to achieve a number of designated objectives” [11, 12].
The Changing Face of Public Broadcasting in India
Published in IETE Journal of Education, 2023
There are four different types of audio broadcasting systems in use, namely: Amplitude Modulation (AM)Frequency Modulation (FM)Digital Radio Mondiale (DRM), DRM30 for use below 30 MHzDRM + for use at VHF band I 47–68 MHz and VHF band II 88–108 MHz
High-power shortwave DRM transmitter in solid-state technology
Published in Automatika, 2018
Goran Pavlakovic, Silvio Hrabar
With the advent of electron tube technology in the 1920s, power amplification of electrical signals has played a key function in radio broadcast systems. Those early years of broadcasting offered low efficiency, bulky transmitters. All of the stages inside the early transmitters included vacuum tubes [1]. With the request of lower capital and operational costs, modern shortwave transmitters employ a single electron tube, while the driving amplifier and the modulator unit have been fully transistorized. The electron tube is used only in the output stage, obtaining high-power amplitude-modulated RF signal in the shortwave band (3.9–26.1 MHz) with frequency auto-tuning systems. With the technological improvement in electron tube technology that took place in the late 1980s [2], today’s modern shortwave transmitters achieve anode efficiencies up to 83%. This leads to the overall transmitter system efficiencies of more than 70% [3,4]. The single-tube shortwave broadcast transmitter design has been an active field in radio frequency (RF) engineering since the mid-1990s [5–8]. On the other hand, since about 1984, medium-wave broadcast transmitters have turned from the electron tube design to a fully solid-state modular design [9]. This approach offers high overall efficiency (>85%), good audio performance, and higher reliability (there is no inconvenience that occurs when the electron tube fails) [10]. Broadcasting in the shortwave bands, although not as vigorous as before due to the introduction of modern communication technologies (Digital Audio Broadcasting (DAB), Digital Video Broadcasting (DVB), wideband Internet access), still provides an effective means of reaching the distant audience by using high-power shortwave broadcasting systems[11]. An attempt of introducing digital modulation techniques into the shortwave broadcast bands comes in the form of the Digital Radio Mondiale (DRM) standard that introduces Orthogonal Frequency Division Multiplexing (OFDM) modulation techniques in the existing Amplitude Modulation (AM) broadcast bands [12,13]. Using this approach the audio quality on AM bands is the same as in FM bands [14,15]. Modern high-power single-tube shortwave broadcast transmitters are built to accommodate both AM and DRM transmission mode.