Moving Right Along
May 1, 2007
The state of surveillance for school bus and transit is primarily not live monitored,” declares Ian Radziejewski, president of Seon Design Inc., Coquitlam, British Columbia. “The main reason goes to another question: What are the transmission technologies? Up to this point in time, there really has not been the bandwidth to support true live monitoring.”
Having the manpower for live monitoring with fleets of several hundred vehicles on the roads in some municipalities and regions is another concern, Radziejewski points out.
“There definitely is an interest to introduce that kind of capability,” he admits. “It may be more incident-based, where there may be an alarm reported on a particular video system and they want to have real-time video monitoring of what the current situation is.”
He cites a technology and cost gap as being the reason for restrictions on live video. “There’s been data over cellular for a number of years, but monthly data costs have been somewhat prohibitive for a lot of government organizations,” Radziejewski concedes. “They certainly do have random access, where they can call out to the vehicles or have the vehicle initiate an outbound transmission. That’s a very time-limited type of transmission.”
For years, ruggedized VCRs have been used to record video in moving vehicles, such as police cars, school and transit buses and trains. In the last few years, the conversion to DVRs has begun, combined with transmission of video from the vehicles themselves.
Jeff Brummett, president of American Sentry Guard, Greenwood, Ind., points out that mobile applications are challenging ones for digital products because of shock and temperature conditions.
“Those things have been barriers for digital technology, but slowly they are being overcome,” Brummett maintains. Digital products that are stable in those environments have opened up a whole new field of surveillance, he marvels.
“You can do so many more things with digital technology than with analog on a mobile system,” he asserts. “The ability of the digital system to integrate with other digital technologies, such as GPS tracking and computer data coming off the vehicles, allows a sophisticated high-end mobile DVR unit to be able to track whatever information you can imagine.”
This includes oil temperature, tire pressure, mileage, even whether a taillight is out. “Whatever you can imagine, we can monitor it on a vehicle and send that data halfway around the world at the speed of light real-time,” he maintains.
His company does this by using cellular telephone technology that searches out whichever cellular company has coverage in an area.
Another advanced wireless system is in Europe. “We’re doing some real-time [video] over public network communication in Europe,” reveals John White, national sales manager â€” transit systems, video intelligence solutions group, Verint Video Solutions, Denver.
“In the U.S., some pilot systems are being done, but nothing full-fledged,” White concedes. “The capability is there today, and the issue is not on the video side â€” the issue is the size of that wireless pipe. The amount of data they can push through is really the limiting factor.”
The same is true with private radio systems, which is another option besides 802.11 Wi-Fi systems and cellular telephones.
One of the most common types of mobile video systems in use today is recording video on buses with several cameras or police squad cars and automatically downloading it wirelessly when the vehicles return to their yards or stations. In some cases, only requested video is downloaded. For others, the entire run of the vehicle is archived for varying lengths of time.
Other options for obtaining data is viewing it on the vehicle itself, or uploading it to a laptop that is carried onto the vehicle. Another technique used is having removable hard drives that are taken to an office for uploading and retain their watermarking for legal purposes.
HOW WIDE IS WI-FI TRANSMISSION?Currently, the most common wireless communication method from vehicles is various versions of 802.11 transmission known to consumers as Wi-Fi. Although widespread, Wi-Fi has a limited distance of several thousand feet under varying conditions and requires frequent repeater stations called nodes. Another wireless method communicates similar to Wi-Fi on 4.9 GHz and is reserved for government use.
Some cities are setting up such Wi-Fi networks and have put repeating nodes along their bus routes for transmission of live video from them.
OTHER WIRELESS TECHNOLOGIES“What we’re seeing more and more is mesh wireless networks are starting to take off,” reports Fredrik Nilsson, general manager of Axis Communications in North America, Chelmsford, Mass. Such a system is self-healing because the nodes are decentralized similarly to the Internet and find the best way to reroute information themselves.
“It’s mostly appropriate for city centers, where you can put up a lot of nodes fairly close to each other and get redundancy,” Nilsson declares. “Anybody who is in the vicinity can tap into it – a police car or bus, it doesn’t matter â€” as long as you have authority to get into the network.”
Only cellular telephone transmission is long-range, he points out. “A mesh network needs nodes to make it work well, and streaming live video over that would be too much for a network now with today’s technology,” Nilsson asserts. “But to be able to tap into specific cameras is definitely possible.”
With today’s technology, Wi-Fi broadcasting is being done by onboard DVRs and extends several hundred to several thousand feet. It is be used by police or other first responders in emergencies to view live video of what is transpiring on a vehicle in real time.
As cellular telephone networks develop greater capacity, the same technology that sends photos from camera phones can be employed to deliver live video at varying speeds to customers.
Addressability is the key issue here. Because of the cost of cellular telephone time, such systems usually are used to look in on vehicles rather than transmit continuously. Most such systems also record all the video on an onboard DVR.
As 3G cellular telephone networks become more widespread, the capabilities for live video transmission from moving vehicles is expected to improve.
Another possible wireless communication method for video is municipal police radio frequencies, but download speeds are thought to be too slow for most video.
Satellite telephone connections also are a possibility but currently are very expensive. “Most satellite applications are going to be military or government,” maintains Brummett.
Wi-MAX wireless transmission, which promises higher transmission speeds and range, has not been implemented in most areas and is not yet being used in most mobile video applications in the United States.
“There are some transit authorities that have been looking at implementing Wi-MAX along certain bus or train routes,” Radziejewski reports.
A system has been demonstrated in the Silicon Valley area of California that transmits video from a moving train using Wi-MAX and wireless 3G transmission. A similar system is in use on a single train line in Singapore and has been demonstrated in Hong Kong, Düsseldorf, Valencia and Delhi.
But the technology used depends largely on what the wireless companies decide to install rather than what the transportation or security industries need.
“It’s almost a wait-and-see approach,” Radziejewski continues. “What technology will become widely adopted for other uses? Then we can piggyback on that for our security needs.”
TRENDSS.T. Pan, vice president of engineering for Global e-Point Inc., City of Industry, Calif., sees use of solid-state memory hard drives in the future. “They are very expensive today, but their cost is going down pretty quickly,” he maintains. His company’s air works division is providing a 30 GB solid-state memory drive for an airline.
“You don’t have to worry about vibration, and solid-state memory can sustain a wider temperature range,” Pan declares.
Radziejewski expects higher-quality digital video to be added to systems in the next few years. “Most cameras are almost entirely analog at this point,” he maintains.
Nilsson thinks that digital video handles vehicle vibration better. “We found out that a lot of those environments are shaking a lot from subway trains and buses, and video using progressive scan has some tremendous benefits because of image clarity.”
He maintains that because progressive methods scan each line of video in order sequentially, paused images from progressive scanning are not as blurred as those from video that uses interlaced scanning. With interlaced scanning, which is used by analog video surveillance cameras, two separate scans, one of the even lines in a picture and the other of the odd ones, are combined.
Nilsson also thinks video will become commonplace on buses, trains, planes and boats. Tamper alarms are another trend he cites if anyone covers or repositions cameras or sprays them with paint. Additional uses such as passenger counting and more built-in intelligence, such as recording at a higher frame rate when an emergency brake is pulled is another trend Nilsson predicts along with higher speeds of cellular transmission.
“I don’t see wireless replacing onboard recording at this point,” predicts Mark Provinsal, vice president of marketing for Dedicated Micros Inc., Chantilly, Va., although he concedes it could happen in the future when enough bandwidth is available.
Another factor that might influence mobile video in the future is long-range Wi-Fi. The world record for long-range Wi-Fi broadcast reportedly is 137.2 miles between two mountains in Idaho, but it was an experiment with specialized equipment not yet commercially available.
Randy Covey, business development manager for SafetyVision L.P., Houston, adds that once the 802.11n specification is ratified later this year, “We’ll se a whole slew of new products that are coming out dramatically increase the speed of the Wi-Fi network. As soon as that happens, you’ll get more data faster off the mobile units.”