The BBC European DSNG vehicle the Eurovan

Transcription

1 The BBC European DSNG vehicle the Eurovan J.M.M. (BBC) BBC News has introduced a new digital SNG vehicle called the Eurovan which, ultimately, will be stationed in continental Europe rather than in London. Based on an 8 Mbit/s digital system with Ku-band uplinks, it is compliant with both the Eutelsat and the Intelsat systems. 1. Introduction In early 1995, BBC News decided to build a satellite newsgathering vehicle (SNV), designed to operate in Europe. It would be based on the European continent rather than in London and, potentially, would give a faster response to breaking news stories in Eastern as well as Western Europe. The criteria were that it had to be responsive and cost-effective to operate, with a range of facilities that would service the newsgathering needs of radio as well as television. It would be required to provide contributions for the BBC s domestic services as well as BBC World Service Television from a range of locations across Europe. 2. Outline specification BBC News already had a number of satellite uplinks, both flyaway and vehicle-based, including DSNV1 the BBC s first digital satellite newsgathering (DSNG) vehicle. This particular vehicle had been very successful in the UK and it was decided that a variant of it should be built for operation in Europe. The result is a fully self-contained vehicle called the Eurovan which can meet challenging resource demands from BBC news editors in a way which would not have been possible five years ago. This has been achieved by the very careful and considered provision of facilities, tailored to the needs of BBC News. The Eurovan was specified to include the following features: a bit-rate of 8 Mbit/s; a Ku-band digital satellite uplink, compliant with Eutelsat and Intelsat regulations; bi-directional studio/ob communications, also via satellite; two-machine BetaSP editing facilities which, although built-in, could be removed from the vehicle for independent operation; a separate BetaSP feed facility, allowing the editing to occur simultaneously with the programme feeding; an on-board single camera with lighting, for live inserts to news programmes; Original language: English Manuscript received 23/8/96. 43

2 Figure 1 General view of the BBC Eurovan. an on-board power generator. It was also required that the vehicle should be compliant with ETS [1], in order to meet individual EC-member regulations for SNG uplinks. The Eurovan had to have a gross vehicle weight (GVW) of less than 7.5 tonnes as, under UK driving regulations, no special licence would then be required to drive it. The first DSNV had been based on an Iveco Ford Hi-Cube Daily, which has an overall length of seven metres and a GVW of six tonnes. For the Eurovan, the Iveco Ford Daily with left-hand drive was chosen; it is six metres long and has a GVW of five tonnes. This has resulted in a compact vehicle that contains all the facilities required, and which is able to move swiftly from one location to the next. Megahertz Communications of Cambridge (UK) won the contract in mid-1995 to construct the new vehicle. The Eurovan was designed to be operated by a single multi-skilled engineer. Such an individual could edit material and feed it back to base via the uplink, only needing extra help when doing a live interview or insert. In that scenario, another multiskilled engineer or cameraman could operate the on-board camera while the first engineer operated the uplink. 3. Digital SNG system The Thomson (France) 8 Mbit/s variant of the ETSI system [2] has been utilized in the Eurovan. Its use by BBC News had already been established with DSNV1 and, for the time-being, it is the preferred system of BBC News for digitallycompressed uplinks despite the progress of MPEG-2 systems. The relatively lengthy codec delays of MPEG-2 systems, when added to satellite delays, can produce very awkward effects on live two-way links. On the other hand, the Thomson 8 Mbit/s variant produces a picture output of adequate quality for the editorial needs of BBC News, and the year-on-year revenue savings from using cheaper digital space segment make it a powerful tool for cost-effective newsgathering. The DSNG system consists of programme video and two audio channels, digitally multiplexed and compressed together via the Thomson 8 Mbit/s encoder. The signal multiplex is uplinked as a Kuband data signal via a 300 W high-power amplifier (HPA) and a 90 cm antenna, permanently mounted on the roof of the vehicle; this gives a maximum EIRP of 63 dbw. The uplink system is an Advent Communications (UK) Newswift. It was decided that, as with the first DSNV, the Eurovan would use a multiplexed single-channelper-carrier (SCPC) bi-directional communications link. This signal is QPSK-coded at a data-rate of 64 kbit/s, integrated with the main programme satellite link, and provides interrupted foldback (IFB), telephone and newsroom computer connections, all in one package. The use of 64 kbit/s SCPC for this purpose is very versatile in terms of operating the vehicle, as full programme comms are established as rapidly as the main 8 Mbit/s programme link. It is also economical in transponder bandwidth, and some satellite operators DSNG DSNV EIRP ETSI FEC GVW HPA IDR IF IFB MPEG PBX QPSK SCPC SNV Abbreviations Digital satellite news gathering Digital satellite news-gathering vehicle Effective isotropic radiated power European Telecommunication Standards Institute Forward error correction Gross vehicle weight High power amplifier Intermediate data rate Intermediate frequency Interrupted foldback Moving Picture Experts Group Private branch exchange Quadrature (quaternary) phase-shift keying Single carrier per channel Satellite news-gathering vehicle 44

3 include this extra bandwidth at very low cost when a 9 MHz slot is already being used for the 8 Mbit/s programme link. Obviously there is also a return uplink comms path from the studio to the vehicle location. As a result, studio/ob communications are much enhanced, giving great flexibility in the operation of the vehicle and much-reduced revenue costs for this type of facility. 4. Programme path The vision signal from the camera is fed via an optical fibre to the vehicle, along with associated programme audio and comms. This fibre-optic cable can also carry return video and comms signals from the vehicle to the camera position. The video and programme audio is then fed to the Thomson 8 Mbit/s coder (see Fig. 2) and sent as a serial data stream to the 8 Mbit/s modulator. From here, it is modulated as a 3/4 FEC QPSK signal with overhead framing information, in accordance with Intelsat IDR specification IESS 308 [3], and this signal is then fed to two stages of upconversion. The first stage frequency-translates the QPSK signal from a 70 MHz IF to an L-band (1.4 GHz) IF and the second stage then converts it to the uplink frequency in the 14 GHz band. 70-MHz IF Upconverter Video in Ku-band Modem 8 Mbit/s coder Audio in Programme HPA Combiner Ku-band Upconverter Modem 8 Mbit/s coder 70-MHz IF Analogue inputs & outputs Comms Using a spectrum analyser, the uplinked signal is monitored off the satellite via the uplink antenna (although the return signal from the satellite cannot be decoded due to its very low level). In addition, there is a satellite receiver fed from the uplink antenna to assist in setting up and finding the correct satellite. 5. Communications The 64 kbit/s comms system is more complex in operation than the programme vision and audio. It is bi-directional and relies on the synchronous operation of two data multiplexers working in a master/slave relationship. The master multiplexer is at BBC Television Centre in London and the slave is at the vehicle on location. It is easiest to consider the Television Centre end of the system first. Four discrete communication channels are combined in the multiplexer: IFB (cleanfeed/mix-minus); talkback; telephone; Basys newsroom computer. The multiplexer is locked to a master clock source, and the multiplexed signal is fed to a modem and then to an upconverter before being fed to a small HPA at the hub of the Television Centre antenna. (The antennae used for News operations at BBC Television Centre are predominantly deployed for downlinking but a number of them are fitted with transmit side-chains for uplink applications.) At the vehicle (slave) end, the received 64 kbit/s signal is downconverted, demodulated and fed to the slave multiplexer. Here the inverse process from that at Television Centre occurs and the decoded IFB (cleanfeed/mix-minus), talkback, telephone and Basys newsroom computer signals are derived. At the vehicle, the return half of the talkback, telephone and Basys signals are fed into the transmit side of the multiplexer (see Fig. 2). The output of this multiplexer is fed to a 64 kbit/s modem, then combined with the programme signal at L-band. Finally, the composite programme/comms signal is fed to the vehicle HPA and the uplink antenna. Figure 2 Schematic of the BBC Eurovan satellite system. 45

4 On deployment, the cab area is converted into a work position for the reporter/producer. A worktop is inserted between the front seats and the reporter is then able to use a laptop computer as a fully-functional dumb terminal of the Basys computer system at Television Centre. Cellular telephones and a fax machine are also provided, as well as a standard office telephone which is connected via the 64 kbit/s comms system to the Television Centre PBX. Hence, anyone at Television Centre can telephone the vehicle simply by dialling an internal PBX extension number. The rear of the vehicle provides storage for the cameras, fibre-optic cable and all the other equipment required to provide a live interview or insert (tripod, lighting etc). It also houses the built-in 12-kVA Fischer-Panda generator, which supplies all the vehicle power that is required, plus some to spare for scene lighting. This water-cooled diesel generator is very quiet, and is fuelled from the same tank as the road engine. Figure 3 View of the equipment bays built in to the BBC Eurovan. 6. Vehicle layout Every part of the vehicle interior is used, as space is at a premium. The interior is split into three parts (see Fig. 4): the cab area in the front; the operational area in the middle; the storage area at the rear. The operational area contains four equipment bays which house virtually all the broadcast plant, including the satellite uplink. There is a small observation window at the top rear of this area which overlooks the antenna well, enabling the engineer to observe the antenna during deployment and stowing all under remote control from inside the vehicle. 7. Fibre-optic system The fibre-optic system, manufactured by Telecast Fiber Systems (US), has proved to be revolutionary in terms of the way the SNV operator is able to rig quickly on location and is able to provide a significant number of signal paths between the vehicle and the live position. The camera signal is fed into the fibre-optic cable by way of a clamshell a small box, powered by a standard camera battery, which converts electrical signals into modulated light signals and vice versa. It is a bidirectional system which provides the following signals: a) From vehicle to live position 1 programme video signal; 2 programme audio signals; 2 comms channels. Front Side door Generator Rear Work-top Worktop bays storage Figure 4 Plan view of the BBC Eurovan layout. bay 46

5 b) From live position to vehicle 3 programme video signals; 6 programme audio signals; 2 comms channels. There is a corresponding rack-mounted clamshell unit (interconnection box) in the vehicle, and there is a degree of flexibility in how the system can be configured. The vehicle carries one drum of fibre-optic cable, 500 m in length and weighing about 15 kg! Additional lengths of fibre-optic cable can be joined on and of course there is no need for equalization irrespective of the length of fibre-optic cable used. A limited amount of multicore cable is also carried to enable other outside-source facilities to be picked up adjacent OB vehicles, conference feeds etc. There is a tailboard connection panel just inside the rear doors, allowing all connections to and from the vehicle to be terminated at one convenient point. 8. Conclusions The Eurovan has been very sussessful in meeting the editorial needs of BBC News. In BBC terms, it has broken new ground in the field of newsgathering by its use of state-of-the-art technology and multiskilled staff. Introduced into service in November 1995, it has already covered a number of significant news stories in the UK and in continental Europe. Since the first Eurovan entered service, another DSNV has been completed and we are hopefully about to embark on the construction of a third DSNV. The permanent deployment of the Eurovan in continental Europe cannot be too far away a number of BBC European bureaux are vying for it to be based with them. There can be no doubt that the Eurovan and other, even more compact, DSNG vehicles are the way to the future. Bibliography [1] ETS : Satellite Earth Stations and Systems; Satellite News Gathering (SNG) Transportable Earth Stations (TESs) [2] ETS : Network Aspects (NA); Digital coding of component television signals for contribution quality applications in the range Mbit/s ETSI, November [3] IESS-308 : Performance characteristics for Intermediate Data Rate (IDR) digital carriers (Standards A, B, C, E, and F earth stations) Intelsat, August Figure 5 Rear view of the BBC Eurovan showing the equipment storage on the left and the generator on the right. Mr. Jonathan qualified from Wolverhampton Polytechnic with a Higher National Certificate in Electrical and Electronic Engineering in He joined the BBC that year and became a Supervisory Engineer in 1983, working in telecine, VT and studios but later going out on the road as a microwave links/ob engineer. When the BBC News & Current Affairs directorate was created in 1989, Mr. became a Duty Manager in the Location Facilities Unit. He later became the unit s Operations Manager and then, in 1992, was promoted to Manager Location Facilities. Today, Jonathan is in charge of a busy newsgathering engineering unit which operates fastresponse terrestrial microwave links and SNG uplinks in the UK, as well as Ku- and C-band SNG uplinks around the world. He has been very involved in the development of vehicle-based and fly-away SNG links and, in particular, DSNG uplinks. He oversaw the construction and introduction into service of the first (analogue) SNG truck for BBC News in 1992, followed by three digital SNG trucks. He is currently planning a new DSNG truck and is also involved in the specifying and maintenance of ENG equipment. 47