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Digital Wireless Camera Round-up (IBC 2002)by David Fox Digital wireless camera systems were the hottest technology at IBC 2002. Where last year they were mainly prototypes suffering from up to 18 frames delay, this year they offered as little as three lines delay, robust signals, light weight and ready-to-ship packages. Tellingly, the IABM 2002 Peter Wayne Award went to Link Research, for its LinkXP wireless camera system, which epitomises the new breed. There were also other notable systems on show, ranging in price from about 25,000 to 100,000 Euros. |
LINK RESEARCH AND GLOBECAST NEWSNews increasingly needs to go live to a story, but having to stay attached to an uplink truck via a cable means that cameras don't have the freedom to react that producers may like. Analogue wireless links can be used, but they require a lot of setting up, need extra staff to ensure the antenna is pointing in the right direction, and the signal breaks up too easily. Fortunately, there is now an answer in the handful of new digital wireless camera systems that were on show at IBC. Globecast News has been testing one of them, Link Research's offering, for news use in otherwise hard to reach locations. According to Rich Wild, Globecast's technical advisor, a prime reason for wanting to get rid of cables is health and safety, as they can cause problems in public places. Using satellite links can avoid some cabling, but in many city centre locations tall buildings make it impossible to see the satellite from where you need to be. "Jobs come up all the time that we have to say 'no' to because of health and safety, and this would change that," he says. The digital wireless system is also ideal if you are doing an interview in a large building or hotel, where you can't trail cables. "The picture quality is absolutely fantastic. It's faultless. Delay is minimal, so it is not an issue for live stuff," he says. The delay is the lowest he has seen on any system. "It's an absolute doddle to set up." After it has been initially pre-set, "all you do is switch the thing on." He hopes to buy at least one for news use. Unlike some of its rivals, which use more highly compressed 4:2:0 or proprietary codecs, the LinkXP uses MPEG-2 4:2:2 signals. It is also claimed to offer the smallest size and lowest power consumption of any digital system on the market (Tandberg makes the same claim for its latest units). It has an end-to-end signal delay of just 40ms, a single frame, which is only bettered by using considerably more compression. The system has been adopted by Hitachi for integration with its own cameras, with Hitachi becoming Link's distributor for Asia and Africa. "It would be nice to see a slightly more powerful version, to get more range," says Wild. However, in Globecast's tests, the SNG trucks used only the most basic antennae, one on each side of the roof for diversity reception, without elevating masts to take them higher. "It worked safely for 200 metres, with no problems." According to Link, the 100 milliWatts the system has should be enough for typical applications, but it is going to introduce booster amplifiers for helicopters and similar uses where the transmitter is on a vehicle rather than on a person. "On the edge of the signal, break up is minimal. We got little lines of black flashing across the pictures. So, you simply say to the cameraman, 'stop, take two steps back, and that's the limit'," he explains. It is easy to establish the limits before going on air. While they were testing it, the story of the missing/murdered English girls, Jessica and Holly, broke and the camera was sent to Soham, near Cambridge. "It was perfect live. We were totally happy with it. There was no break up if you were in the [safe] area. The cameraman can vanish around corners and out of sight and, although a building in the way reduces the distance, it still works," he says. "It is perfect for fast-moving situations, such as war zones, where cameramen and reporters have to move fast." He also feels it would be well suited to sports, where it will mean not having to cable a stadium, especially as several cameras can use the same antennae. Indeed, he would like to see these abilities expanded with permanent set ups in cities, where a network of antennae could be established to avoid the need for any uplink trucks. "If everyone is allocated a separate frequency, there is no reason the signals couldn't all come back to a single point and then go to the right broadcaster," he believes. "The one essential thing would be to have a return link back to the camera unit for basic communications, so that the journalist can hear what's going on back at the studio," he says. "Other than that, it is ready to go." Reverse communications back to the studio will be available for the LinkXP at NAB. At £33,000, "it is not a cheap system, but they've all been cost prohibitive up till now, but after a year it will probably have paid for itself." All the earlier systems have been too big, the best, he feels, being the Tandberg Voyager, which was worn like a backpack. But the new systems shown at IBC have all been a lot smaller, with Link's about the same size, and weight, as a large battery. "You barely know it's there." Globecast is the broadcast division of France Telecom, which provides end-to-end facilities to broadcasters, including cameramen, editing and uplinks.
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GIGAWAVEGigawave is at the centre of three of the digital wireless packages launched at IBC, with two of its own and one it is manufacturing under license for the BBC. "We're offering the two extremes. You can't have an extraordinarily robust modulation scheme and near instantaneous pictures. We offer both, in the same camera, just by changing a card." A card also has to be changed in the receiver, but the changeover takes about a minute. He sees quality, delay and RF robustness as the key issues. In Gigawave's case, delay is addressed by wavelets; quality by MPEG-2, from 5Mbits per second to 18Mbps (or slightly higher for the very best quality); while robustness is obtained from QPSK and MPEG at 5Mbps. Different types of programmes need different things. News needs robustness and light weight, and sometimes will need low delay. Outside broadcasts need low delay to synchronise with other cameras and to synch sound. However, if all the cameras at an event are on a wireless system, then users could aim for quality only, as all of them would have the same delay. Like most digital wireless packages, the Gigawave solution takes the place of a recorder in a dockable camera, as recording is not an issue for OB use. "They want a fully integrated system that looks good, is reliable and robust. Whereas for news you want light weight, and this weighs no more than a recorder would. It gives a well-balanced system." Gigawave has shipped a small number worldwide, but many more deliveries are imminent. The systems have mainly been used for sports and ceremonial events. All these technologies can also be applied to microwave links, and Gigawave now offers small portable digital microwave links offering wavelet and MPEG-2 compression, although Scott believes most users will go for MPEG, as delay is not so important with links. The MPEG can be any data rate users want, although Gigawave will probably implement it as six options on a switch. It is currently configured via a PC. Gigawave is also doing a lot of work on customised antennae. "If you have a building with a lot of rooms, you might need different antennae in each area for maximised coverage," he explained. Line of sight is typically 1km, but in buildings or a cluttered environment, it is more likely to be a few hundred metres.
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BBC VENTURES INTO WIRELESS MARKET The system has been improved considerably since being shown as a prototype at IBC 2001, with delay down to three frames and robust new diversity reception. Compared to the two Gigawave systems, with which it shares some components (dockable interface, camera control systems and antennae), it is a compromise. "They've each got advantages. DVCPRO 25 is reasonably low delay and reasonably good and proven compression. It's halfway between the [Gigawave] two," said Scott. "It was developed with a remit to fulfil programme makers' needs in the BBC. Producers won't work with it if the delay is too much or it reduces picture quality," said Jon Murthy, business development, BBC Ventures Group, who feels other systems make too many compromises. "The programmes we use it on have a mixture of cable cameras and wireless cameras and unless you can mix between the two you can't use it." He believes that not having cables also benefits viewers as the camera can get closer to the players without cables getting in the way. BBC Outside Broadcasts has 13 in use, mainly for sport, particularly soccer and athletics, but also for shots it couldn't get otherwise, such as in the Royal Albert Hall for Last Night of the Proms, for a walk from the main auditorium to the backstage area where musicians waited to go on. "Analogue wouldn't work, but now we have seamless pictures, going from receiver to receiver, because of the diversity reception and the ruggedness of the coding," explained James Smith, communications engineer, BBC OBs. "It can deal with the reflections and use them for its benefits, to fill holes where it doesn't have data." It has been uses a lot in sports stadia, such as Manchester United's Old Trafford, a very high-sided stadium, where using analogue wireless systems required a cameraman, a pole man, and someone panning the dish. With digital just a cameraman is needed. For the Commonwealth Games, also in Manchester, it used ten digital radio cameras at once in the same location, which would have required thirty people with analogue. "From an operational perspective, they make my life so much easier," said Smith. "You don't have to do all the testing you had to do with analogue. Just turn it on and it works." The BBC could easily do a whole production using wireless, but there hasn't yet been a production need. However, Smith expects that as people "see the versatility of being able to put a camera pretty much anywhere without any restrictions, producers will use them more." |
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ATLANTIC FLOATS BUDGET SOLUTIONNewcomer, Atlantic Digital has launched a budget digital wireless camera system that halves the cost of an end-to-end package. "Our technology package is aimed at being a robust, practical, reliable tool for broadcasters and newsgatherers to use," commented director, Richard West. It is aiming for the professional video market rather than high-end broadcast, and should cost about £16,000, a price he feels will also be attractive for low-cost newsgathering. The system fits any dockable camera and has 240ms delay (six frames), but can do 160ms (four frames) in a low-delay mode. Initially it offers 4:2:0 MPEG-2, at 8Mbps, using a DVB-T transport stream, but a 4:2:2 version will be available in future. "This technology has been evolving over the last two to three years. Now it is maturing, but it will start to be bought over the next couple of years," he believes. At IBC, it was demonstrated working at up to about 200m inside the RAI buildings, and outside at up to about 600m. It uses only a single antenna at present. Power consumption is about 16W, giving some two hours usage on a Hytron 50 battery. "A year ago, delay was still half-a-second and reducing latency was the issue, but it is now the quality and robustness of the picture, and we can certainly compete on that," said West. It only has a one-way link now, but a return link for camera control and intercom will be available with the production units when they ship in January. |
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THOMSON MULTIMEDIAThomson Multimedia is to enter the digital wireless camera market with two packages based on its LDK-100 and LDK-200 cameras. The system, set to ship at the end of the year, has been in operation with beta test customers in Holland, France, Italy and Germany. "Feedback has been good about the signal robustness and picture quality, and the integrated control. It looks like a normal camera and feels like it from the control panel," as it uses the same camera control unit as a tri-ax camera, said Jan Eveleens, Thomson's business unit manager for cameras. "Mobility is critical for enhancing the creativity of broadcast productions, from football matches and grand prix racing studio to settings where hosts mingle with the audience," said Marc Valentin, vice president of the Thomson Grass Valley business. "Our digital wireless camera system not only gives camera operators the freedom to move, it lets them move quickly, and without risk of losing their shots. With a system this flexible, the only constraint is one's imagination." The prototype shown at IBC had two frames delay, but this is still being improved, although it may need a software upgrade for the early models to do better. Instead of MPEG-2 compression, it uses a wavelet-based compression system at about 18 to 20Mbps. It does, however, use 4:2:2 10-bit signal processing and a DVB-T COFDM transmission. "With the same bit rate, it allows better picture quality and low latency. That's why we went for this system," explained Eveleens. "The other systems based on MPEG can't beat our picture quality." It has diversity reception, for which Thomson has developed its own antennae, with a range of up to 300 or 400 metres. In the trials, it has proved to have a very robust and predictable range. "The system performs very predictably, but it does have a cut off cliff," he said. "The setup and installation is very easy," he claimed. "We support a roaming concept, so you can move from one area to another seamlessly - from the control point of view also." There is no return path at present, so users will have to rely on separate intercom sets. On the receiving side, the system uses a single unit, which Thomson claims "provides a generous shooting area". For more ambitious applications, such as capturing an uninterrupted shot travelling from a stadium field into a team dressing room, users can deploy a distributed network of receiving antenna management units to provide wide coverage at low transmission power. The system switches automatically between multiple antennas to extend the respective shooting area. The connection between base station and antenna management units uses conventional 8-mm triax cable that can be extended out to a length of 400 meters. The unit is a fully-integrated adaptor for its dockable cameras. However, this takes the place of a recording unit, so the camera can't record direct to tape and transmit at the same time. It runs for two hours on a single NP-50 battery, and a total system package will cost about 100,000 Euros, including the camera head. Nov 2002 |
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Gigawave's
own two variants are: an extremely robust MPEG-2 based system, using QPSK
COFDM modulation; and one using wavelet compression, "which has virtually
no delay, just a few lines," said its technical consultant, John
Scott.
The