IR sees light

Lasers and infra-red (IR) have long been used in the US for communications, but mainly by the CIA. Spies like IR because it is more difficult (not impossible by any means) for the other guys to listen in. In general IR can be pointed better than radio frequency (RF) communications. The higher the frequency the more pointy she gets, is a law of physics. And the more pointy and sharper the beam the more co-located must be your eves-dropping antenna with the antenna being surveilled.

Major civil innovations are being proposed. In one application an IR laser transceiver that can be stuck inside a window is being proposed (WSJ 2/27/01 pB8) as a solution for the ‘last-mile problem’ in broadband communications. That’s linking individual homes and small offices to telecom system switches.

Also sometimes referred to as ‘free space optics’ to distinguish it from the optical communications within a fiber optic cable, IR last-mile equipment is being proposed by San Diego-based AirFiber, Seattle-based TeraBeam Networks and UK-based QuantumBeam. These IR guys call the telecom companies’ DSL Dumb Substitute for Light. DSL which attempts to tune up existing twisted copper pair conductors certainly seems to be in deep trouble, with companies large and small simply unable to deliver reliable broadband service at a paying price.

IR can easily be used for short range data communications such as electronic toll (ET) collection. Austria’s Efkon AG has been offering IR ET systems for some years. In some countries IR systems avoid a lot of regulatory hassle since licenses are required with any RF system. And outside the US there have been RF interference problems with mobile phones. Neither of these issues has generated any interest in IR in the US. Tinted and metallized windshields are quite resistant to RF ET-tags. IR ET is also affected, but Efkon claims, less so.

The company has ET IR systems in five countries but its biggest breakthrough has been Malaysia with about a dozen toll facilities including one of the world’s longest toll roads that goes from Singapore right up to the Thai border on the isthmus. IR and RF systems work perfectly well side by side. On the long Butterworth-Penang Bridge on the west coast an Efkon IR system has replaced a Combitech/Kapsch ET system.

Efkon’s infrared non-stop ETC system is called SmartTAG and is already operating on PLUS and ELITE the two largest systems in Malaysia. . Malaysian tollsters make major use of a proximity card called “Touch ‘n Go.” This covers some 600 toll lanes, and is used for parking, bus and urban trains in Kuala Lumpur.

We asked one US RF guy what he thought of IR. “Great except there’s that great competing radiator of IR up there, called the sun. That can create all kinds of problems.” Maybe less so in Malaysia and lower latitudes, he conceded where it’s right overhead, and the sunrise and sunset are quick. But in the higher latitudes it’s more troublesome, as people operating camera enforcement systems can testify.