The FCC granted a waiver yesterday (November 21, 2008) for a security-system technology that does not comply with its technical rules. No big surprise – the FCC does that, now and then. But this case is a little odd: the system needed a waiver only because it has a lower potential to cause interference than a compliant system does.

A lot of security systems on the market protect buildings by sensing motion in the vicinity. While these can effectively detect intruders, they also detect dogs, birds, and paper blowing in the wind. A real intruder can easily go unnoticed in the flood of false alarms.

A small New Hampshire company called UltraVision has solved the problem. Using a radar technology originally developed for finding underground pipes, UltraVision’s system not only signals an intruder’s presence, but also registers its size, speed, and direction of travel. The sensors can be programmed to ignore birds and sound the alarm for pedestrians and vehicles, or to alarm only for vehicles over a certain size and speed, or whatever the situation requires. With most false alarms eliminated, security personnel can concentrate on the real threats.

For FCC purposes, the UltraVision system is classed as an “ultra-wideband surveillance system.” The FCC imposes two technical rules on these. (Okay, we are simplifying.) Rule 1: Radio-frequency emissions are allowed, up to certain limits, in distinct two bands, which we will call Upper and Lower. Rule 2: The device’s highest emissions must fall in the Upper band.

This is where UltraVision ran into trouble. While it complies with Rule 1, it has no emissions at all in the Upper band, and therefore fails Rule 2. Graphically, the situation looks like this:

Note the irony. The FCC’s technical rules control power, bandwidth, out-of-band emissions, and such in order to limit interference into other units. A device that violates these rules typically presents a greater threat of interference. But here that is reversed. The UltraVision product occupies less spectrum than a compliant device, and complies with all limits where it does operate. (In fact, it complies with the same low emissions limits as a laptop or an iPod.) Yet, because of Rule 2, it requires a waiver of the rules before it can be sold.

UltraVision duly filed a request for waiver back in October, 2006. One party opposed: MSTV, which represents broadcast television stations. The Lower band, where UltraVision operates, overlaps the UHF TV spectrum. MSTV argued that UltraVision would pump more energy into those frequencies than a compliant device, and hence posed a threat of interference to TV reception from as far away as 452 feet. UltraVision disputed the calculation. MSTV, it said, derived the 452 foot figure from a far more interfering kind of transmitter. But for the sake of a speedy decision, it agreed nonetheless not to install its systems within 452 feet of a residentially zoned area, thus eliminating any risk of interference to people watching TV at home. Subject to that condition, and a few others that UltraVision proposed, the FCC granted the waiver.

Sadly, though, homeowners plagued with false alarms on their own security systems are out of luck. In addition to the no-residential-zoning condition, UltraVision agreed not to sell to consumers. Home Depot may have one, but only to protect the store. It is not for sale.