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Analogue radio technology was used in communication and broadcasting for decades. However, after the advent of digital electronics, a new technology emerged – the digital radio. It uses digital signals instead of analogue for broadcasts or communication. As analogue signals suffer from quality loss due to signal interference and obstructions, the digital radio, on the other hand, stands out in terms of audio superiority. It uses a digital radio transmitter, which encodes audio into digital radio signals and can be received using a digital radio receiver. A digital radio receiver encodes the signals back to audio signals using digital-to-analogue converter(DAC) conversion method. As a result, the audio is of a standard quality free of noise.
There are many types of digital radio technology used for radio communication, and one such is called digital radio mondiale (DRM).mondiale is the Italian and French word for 'worldwide'. Just like the analogue AM or FM radio, DRM also broadcasts in AM or FM frequencies but in digital format. With superior transmission quality, it delivers premium audio. AM or FM bands are used, and mostly it uses the shortwave frequencies for AM.
However, DRM is spectrally and qualitatively efficient than AM and FM, allowing more stations into a given amount of bandwidth. Currently, the latest digital radio standard is DRM, a global, open (non-proprietary) system.
DRM uses coded orthogonal frequency division multiplex (COFDM) technology for radio transmission, which resolves the fading problem (common in analogue radio) with the help of cheap but efficient computer processing power.– DRM uses modern audio compression techniques that enable more efficient use of available bandwidth at the expense of processing resources. The AM broadcast used for DRM radio is called DRM30,the frequency range is 30kHz – 30MHz whereas the FM transmission is called DRM+ and has a frequency range of 30MHz – 300MHz. DRM broadcast is done using xHE-AAC audio coding format. It also uses various other compatible codecs like MPEG-4 and Opus codecs, but the standard now specifies xHE-AAC. As DRM radio provides a better radio transmission with superior audio quality, in many countries radio stations have switched from analogue to DRM, including BBC, All India Radio (AIR), Voice of Nigeria, Radio Romania International, China National Radio and many more are broadcasting in DRM around the world.
DRM can not only be used for radio broadcasting, but also for many useful multimedia applications such as DRM text messages, journaline advanced text with listener interactivity and geo-referenced information, slideshows, traffic updates via TPEG or TMC, and service logos via SPI.
DRM uses a different digital radio technology that takes advantage of the COFDM. This technology minimises the Doppler effect (frequencies offsets, spread: Doppler spread) and provides better radio broadcast quality.
COFDM is a telecommunications modulation scheme that divides a single digital signal across thousands of signal carriers simultaneously. The signals are sent as closely packed (non-overlapping) signals so they do not interfere with each other, which takes less bandwidth compared to frequency division multiplexing (FDM). It also uses a code that acts as a forward error correction (FEC) to eliminate data loss from radio frequency (RF) interference or distortion. It is an advanced version of the orthogonal frequency-division multiplexing (OFDM).
In OFDM multiple radio signals are transmitted simultaneously. Still, they are separated from each other so that the amplitude of one signal would only be at the peak level even when the amplitude of the other signal is low. This way, many signals can be packed close to each other, taking less bandwidth but can transmit independently. That is why the word 'orthodox' is given, which means independent. However, in COFDM, the signals are not only transmitted using the OFDM method but also use FEC, and a code is transmitted for every signal. This code carries the information about the signal and the receiver.After receiving the code,the receiver accepts only the signals related to the code. This prevents the receiver from receiving any other similar frequency signals that might be RF noise or interference.
DRM is a digital radio that uses the latest technology for radio broadcasting, with high-quality audio and data (text or image) that can be received using a DRM receiver. DRM’s benefits include universal access (connecting the whole country), flexibility, and greenness (energy efficiency).
DRM radio can broadcast to the whole country using AM bands with DRM30. As the LW,MW, or SW band radio signals can travel thousands of miles from one country to another, DRM30 broadcast can not only give access to news and information to the listeners of one country but also to the listeners of many other countries of different continents. Moreover, unlike any AM radio, a DRM30 can also deliver data, including text and images, to the DRM radio receivers in the form of news and information. This feature makes DRM a radio and an information provider, which can be helpful during any crisis like natural disaster and pandemic outbreaks. Such an information delivery system could alert the listeners about any crisis or danger.
DRM is also flexible compared to other digital radios, they do not have such flexibility. This flexibility makes DRM+ easy to implement. As DRM+ uses FM bands, it is possible to upgrade the FM transmitters to DRM+ without much effort and without affecting the current analogue FM broadcast. A DRM+ broadcast can also be carried out alongside the analogue FM broadcast, making DRM+ easy to implement and use in FM stations.
DRM can be considered green, which means it consumes less power. DRM+ transmitters can consume 50%- 90% less power than other analogue FM transmitters. Such low power consumption of DRM radio makes it one of the best energy-efficient radio technologies in the world.
DRM was founded in the 90s, but due to the minimal use of digital audio and higher cost of digital electronics, worldwide use of DRM was not implemented everywhere then. But after the advent of newer technologies and cheaper digital audio electronic components like digital signal processors (DSP), DAC, and system-on-chip (SoC), the manufacturing of digital radio equipment has become possible with a cost-effective process. With the help of such digital electronics and state-of-the-art technology, DRM radio can now be used around the world to let you experience high-quality digital audio and information in the form of text and images.
Therefore, DRM radio is gradually on the rise, and with all such useful features, it is currently one of the best radio technologies that can provide the ultimate digital radio experience.
