Implementation Of Digital Radio Through Technological Innovations
The dominance of AM during the first part of the 20th century as the preferred radio broadcasting channel was put to an end due to issues such as poor reception, distortion and channel fading. While these problems could be dealt to an extent with the introduction of FM, yet limited area coverage and channel imperfections continued to haunt the radio broadcasting industry. This led to the broadcasters opting for the digital route due to its better quality and the fact that it made possible the recycling of content within the same bandwidth. Among the other advantages offered by digital radio broadcast techniques, the prominent ones include good reception and wide coverage. And thus began the world’s move from analog to digital.
Technological innovations leading to digital revolution
- Digital radio’s existence can be traced back to the evolution of DSP’s and the advancement in information theory. While initially the digital receivers were assembled with different components, market dynamics eventually led to enhancement of the production capabilities by way of integration of the components.
- By converting analog signal into digital and then compressing it, a digital system is able to efficiently utilize the channel’s capacity. The RF signal transmission is carried out by converting the signal into analog. A reverse process is carried out at the receiver’s end in which ultimately the analog signal produces sound. Codec (coder-decoder) with error resilient components facilitates the control of errors.
- By the application of new technological features, the DRM coding is able to deliver the best audio experience. When it comes to audio source coding, although the MP3 format continues to maintain its top position, Apple’s AAC is also gaining attention. Psycho acoustic model, TDAC, binaural cue coding, and SBR are the four innovations in audio source coding that are worth a mention. Improvement in the audio quality had been further made possible due to the innovation in measurement technologies such as PEAQ and MUSHRA.
Architecture of the DRM System
DRM is composed of 3 transmission paths, namely MSC, FAC and SDC. While the SDC contains data required for MSC de-coding, the FAC is responsible for the OFDM signal. THE MSC encodes frames that are generated by the mux via standard, symmetrical or mixed mapping.
Digital processing of signals and functions of micro-controlling are best carried out with the Blackfin processor. Digital radios based on Blackfin processor can be developed using the ADI ecosystem. ADI’s digital libraries for decoding are also helpful. TheHE-AAC v2 is an all-essential decoder that optimizes performance from myriad MIPS.
The components of the HE-AAC v2 integrate to form the architecture of the DRM decoder and the key features include AAC, SBR, and the PS.
The implementation of digital radio was to a greater extent made possible by the efforts and field trials conducted by the ADI. Collaborative teamwork of ADI with the BBC, Dolby and Deutsche Welle, led to the successful development of a Blackfin based DRM radio. Product manufactures thus adopted these new technologies to engineer new digital products. Companies in India and elsewhere are using this reference design to produce DRM radios in bulk.