Locate, Track, Identify

Yet already it's clear there's room for improvement, particularly in terms of the technology's reliability. 11/05/2008 9:56 PM Eastern

Locate, Track, Identify

Yet already it's clear there's room for improvement, particularly in terms of the technology's reliability.

In real estate, location is everything. In pro AV, it's increasingly something, judging by the number of vendors and integrators dabbling in real-time location services (RTLS).

Yet already it's clear there's room for improvement, particularly in terms of the technology's reliability. That assessment comes from users such Brian Hsieh, a sound designer who's been using one type of RTLS–radio frequency identification (RFID) technology–since 2006 for the Chicago and New York productions of the musical "The Pirate Queen."

AMX's Anterus RFID system uses tags and readers (pictured) to wirelessly track the location of AV assets, people, or other objects.

Hsieh and his colleague, renowned sound designer Jonathan Deans, affix RFID tags to performers. The location of those tags are tracked wirelessly and fed to the sound system, which then pans the audio to match each wearer's movement across the stage–all to create a more lifelike experience for the audience. (For more details about the setup, see "Virtual Soundscapes," June 2007.)

Although Hsieh and Deans like the results, they'd also like the system to be more robust. For example, the RFID receivers sometimes have difficulty communicating with the tags, especially when the signal is attenuated by multiple pieces of scenery or layers of clothing.

"If we were to get it working with a certain degree of reliability, I could see lighting guys and automation guys wanting to use it," Hsieh told Pro AV last year. "It's always been every sound designer's dream to have a system like this. It's just a question of cost and reliability."

More Options

In fact, cost and reliability are both slowly improving across the RTLS space, which also includes ultrawideband (UWB) and 802.11 Wi-Fi. All of the technologies have a variety of existing and potential pro AV applications, from tracking the locations of projectors in a convention center to enabling interactive museum exhibits.

The selection of RTLS products for pro AV applications also is slowly improving. AMX's Anterus system, launched in June 2007, is one of the few RFID products designed specifically for pro apps. Anterus includes tags, ID badges, and key fobs that are attached to devices or carried by people and scanned by nearby readers. (If you stopped by AMX's booth at a recent trade show, you saw the system in action tracking the whereabouts of AMX booth representatives.)

Besides being used to track equipment, such as a projector's location, Anterus also can feed that information to AMX platforms such as MeetingManager and ClassroomManager. For example, if the CEO has an Anterus ID badge or key fob, the system could be programmed so that when he approaches the podium, the auditorium's lights automatically dim, his mic comes on, and his presentation is queued up on the projector.

Like other RTLS products, including those using technologies other than RFID, Anterus hints at what possible uses could be ahead as vendors and integrators start dreaming up more sophisticated applications.

"We've tried to keep it fairly simple such that people can get their hands around the technology and begin to experiment with what they could use it for to solve some of their problems," says Robert Noble, chief technology office of Richardson, Texas?based AMX. "What we see going forward is an expansion over time to add more features and functionality, maybe blend some different technologies."

One possibility: Museum patrons could pick out an RFID badge based on their knowledge of a particular exhibit. As they approach each piece, the system determines whether to serve up information–audio, for example–on a layman or Ph.D. level, instead of cramming everything into a one-size presentation that doesn't fit all.

Many enterprises already issue employee ID badges that use RFID or similar technologies to provide access to buildings or computers. But most of those can't be made to interoperate with AV systems such as Anterus.

"The technologies are different and a little hard to blend," Noble says. "But I can see the technologies converging, where you might have one super tag that has all of the technologies blended. They're not there today, though."

RFID's range and reliability also are improving, especially when using what's known as "active RFID," where tags are battery-powered. The other, "passive" type has no power source. Instead, the reader effectively sucks the information out of a tag via a magnetic or electrical field.

Even so, passive RFID also is improving in terms of the range at which it can operate. "We were dealing with a range of a couple of feet a few years ago," says Michael Liard, a research director at New York?based ABI Research. "Now some people are saying they can get tags to read at up to 30 feet with passive."

UWB: Reliable and Precise

"The Pirate Queen" also uses UWB, which transmits Morse code-like pulses of energy to transmit data at speeds of up to 2 Gbs, depending on factors such as signal strength and vendor-specific tweaks. UWB's name comes from the way that it spreads a signal over a far wider swath of spectrum–hundreds of Megahertz–than other wireless technologies do.

That design also makes its signal more resistant to interference than alternatives such as Wi-Fi. The spread-spectrum signal also is virtually immune to eavesdropping and hacking.

UWB has a range of about 30 feet, although the real-world distance depends on the amount of power that regulators allow in a particular country and on vendor-specific tweaks.

For AV applications, UWB has at least three major benefits. The first is low power consumption: tens of microwatts when transmitting, a plus for battery-powered applications. The second is built-in, radar-like abilities that can be used to locate people and objects, with resolution varying between 6 inches and 1 foot, depending on the vendor's design.

For example, Multispectral's DART system, which was used in "The Pirate Queen," can calculate a UWB tag's location at up to 200 times per second. "That makes applications like tracking performers in real time on a stage possible," says Mike Recker, product manager of Vernon Hills, Ill.?based Zebra Enterprise Solutions (ZES), the parent company of Multispectral Solutions.

UWB's third benefit is the ability to plow a signal through multiple physical obstructions, whether it's walls or clothing. That robustness directly affects cost because it means, for example, that fewer sensors might be needed to provide communications and location around a facility.

AV, computer, and telecom vendors have been working on UWB for several years. All of that activity is noteworthy because it's slowly increasing hardware volumes. That will eventually drive down costs, to the point that UWB becomes viable for more AV applications.

For now, the choice comes down to whether an application's reliability, bandwidth, and location requirements justify the price premium.

"UWB is a little more expensive [than Wi-Fi], but it gets you very precise location information," says ABI Research's Liard.

Wi-Fi: Cheap and Ubiquitous

Although Wi-Fi is best known for carrying data traffic and, to a lesser extent, voice calls, the technology also can be used to track the location of an item that's using Wi-Fi.

One way is by using three access points (APs) to triangulate the position. Another way is to map all the locations of all of the APs in a particular area, such as a campus or the floor of a building. Because each AP covers a radius of only a few hundred feet (or much less, if that's how the network is designed) identifying the AP that the device is connected to provides a rough location.

Regardless of the basic technique used, vendors also often layer on their own hardware and software to increase the precision.

"We are currently targeting 5 to 6 meters, basically room size," says Perry Correll, director of product marketing at Xirrus, a Thousand Oaks, Calif.?based maker of enterprise Wi-Fi products. "The more radios that can see the [device], the better we can do. Some newer capabilities we are adding should be even better."

Wi-Fi is similar to UWB in the sense that it can do double duty: help discern location and carry something, such as mic audio. And Wi-Fi is similar to RFID in the sense that it's widely deployed in a variety of industries, which means high equipment volumes that help drive down hardware costs.

But depending on the application, one of Wi-Fi's biggest potential downsides is high power consumption. For example, if the technology is used for extended periods, such as the duration of a play, then poor battery life may be a significant drawback. But if it's used only intermittently, or if it's attached to a device that's plugged in or has a big battery, then power consumption is less of a concern.

For simple asset tracking, another option is ZigBee, a short-range wireless technology that's used in industries such as health care and energy management. The technology is relatively new compared to Wi-Fi and RFID, but it's gaining adoption partly because of its low power consumption. The catch is that its batteries last longest when the tag hibernates for extended periods, wakes up, bleats out a few bytes of information–such as the device's status– and then goes back to sleep.

"They have tags that are a bit bulky but will go for eight to 10 years," says AMX's Noble.

Wi-Fi may be worth considering if the client already has a wireless local area network (WLAN) because reusing that infrastructure could be less expensive than deploying a new, separate system for AV location.

However, those savings can erode quickly if adding location support to the existing WLAN requires a lot of extra APs. Although enterprise-class APs are relatively inexpensive, there can be steep hidden costs, such as union labor for pulling cables to each one.

ABI Research believes that for location applications–regardless of industry–Wi-Fi and active RFID will coexist for the next five years. Add in UWB and even ZigBee, and integrators have plenty of RTLS options. AV

Tim Kridel is a freelance writer and analyst who covers AV, telecom, and information technology. He's based in Columbia, Mo.

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