DIGITAL RADIO GUIDE

SATELLITE TRANSMISSION - WORLDSPACE

5 Satellite Transmission

The Broad Picture

For many years, satellites in geostationary orbits (GSO’s) have been used successfully by broadcasters for distributing programmes and services from the originating studios to terrestrial transmitting stations. It is cost effective and reliably delivers high quality signals to each transmitting station. This method of distribution is of particular benefit to international broadcasters that in the past relied on SSB and DSB short-wave signals for feeds to remote relay stations.

Today, radio broadcast services can be included in the bandwidth used for an FM satellite television signal, or as part of a bundle of digital channels as used in Astra Digital Radio. In all cases, satellite tuners are needed to receive these broadcasts, which are usually transmitted in the Ku Band.

Direct radio broadcasts from geostationary satellites to fixed receivers with externally mounted line-of-sight antennas is routine and presents no problems. It is a much more demanding requirement to reach receivers that are mobile or portable, but the majority of radio listeners have radio receivers of this type. Any radio transmission system, terrestrial or satellite, which fails to deliver a satisfactory service to such receivers will probably not find widespread acceptance.

The main difficulty in providing a satellite broadcast to an audience on the move is occasional blockage by buildings etc. This can reduce the signal by 10 to 20 dB, which it is impractical to compensate for with an increased link margin.

5.1WorldSpace – ITU-R System D

WorldSpace is a commercial organisation based in Washington D.C. with world-wide interests. It has planned for three geo-stationary satellites, named AfriStar, AsiaStar and AmeriStar to provide global coverage. They will have L-Band payloads and each satellite covers its designated target area with three “spot” beams. Each beam has two transponders (one transparent and one with on-board processing). The aim is to provide digital radio and ancillary services to audiences in the footprints of these satellites using ITU-R Digital System D. As the names imply, the continental zones to be served by these satellites are Africa, Asia and Central and South America. See Figure 5.1.

The primary aim of the original WorldSpace concept is to provide a simple radio service, but as the project has developed, there is now more emphasis on mobile and multimedia features involving data and image transmission. Trials of MPEG-4 video have been successfully completed recently.

The WorldSpace project is innovative and has a number of points in its favour. These include the size of the coverage areas in relation to the cost of the satellites, advanced low bit-rate audio coding and straight forward satellite uplinking arrangements. An enhanced service using terrestrial repeaters for reliable mobile reception is has been successfully trialled and is being planned for introduction soon.

The approximate target regions for the transmissions from each satellite in the WorldSpace system are shown in Figure 5.2. AfriSpace commenced operation in 1999 and AsiaSpace in 2000. AmeriSpace has not been launched. Consideration is also being given to planning an additional satellite for providing service for Europe.

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Grundig Digital Radio manual Satellite Transmission, WorldSpace ITU-R System D, Broad Picture

Digital Radio specifications

The Grundig Digital Radio represents a significant advancement in radio technology, combining aesthetics, functionality, and a user-friendly interface. As a pioneer in the audio and electronics industry, Grundig has successfully integrated modern digital capabilities into its traditional radio design, appealing to both nostalgic listeners and tech-savvy users.

One of the standout features of the Grundig Digital Radio is its versatility in reception. With DAB+ (Digital Audio Broadcasting) technology, users can enjoy a wide array of radio stations with superior sound quality, free from the hiss and interference commonly associated with analog broadcasts. The inclusion of FM and AM bands ensures that listeners are not limited, providing access to local stations that may not yet have transitioned to digital.

The Grundig Digital Radio is designed with ease of use in mind. Its intuitive interface, often featuring a clear LCD display, allows users to navigate through stations and settings effortlessly. Many models also include a built-in tuner that automatically scans and presets available stations, simplifying the setup process. For those who appreciate personalization, some variants come equipped with customizable presets, allowing users to save their favorite stations for quick access.

Portability is another key characteristic of the Grundig Digital Radio. Many models are lightweight and come with built-in handles, making them ideal for on-the-go listening, whether it's in the garden, on the beach, or during a picnic. Battery options, alongside mains power, ensure that users can take advantage of their radios wherever they choose.

In terms of sound quality, Grundig utilizes advanced audio technologies to deliver rich and clear sound. Enhanced bass responses and treble controls allow users to fine-tune their listening experience to match their preferences. Furthermore, many models feature additional inputs, such as AUX and USB ports, enabling users to connect their smartphones or other devices, expanding their audio options.

Other notable characteristics include built-in alarms and timers, which make the Grundig Digital Radio a versatile companion for daily routines. Some models even support Bluetooth connectivity, allowing for seamless streaming from a variety of devices.

In summary, the Grundig Digital Radio embodies the perfect blend of traditional radio appeal and modern digital technology, offering versatility, ease of use, superior sound quality, and portability to meet the diverse needs of today’s listeners. Its well-thought-out features and user-friendly design make it an excellent choice for anyone looking to enhance their audio experience.