During a high-risk entry, SWAT teams have door cameras they can use but they can be noisy to deploy and are easily defeated by the person on the other side. Time Domain (Alabama) markets RadarVision, a handheld device that uses ultra wideband (UWB) pulses to see through walls. UWB tries to solve two problems for tactical teams: (1) knowing whether there are people inside the building, and (2) knowing where they are before making a tactical entry. Ultra wideband is a type of radio transmission that enables high-speed communications, precision tracking, and the detection of movement behind walls. The difference between it and more traditional radio transmissions is that it sends information in very short pulses of energy versus a continuous wave. UWB transmits short pulses across all frequencies and might interfere with other radio energy transmissions were it not for strict power limits imposed by the Federal Communications Commission (FCC). To ensure UWB operates in a safe range, the FCC requires users of UWB to limit transmission to levels that are lower than junk radio energy. Two products have become available for tactical use: RadarVision and Ultra Vision from Geophysical Survey Systems Inc. (New Hampshire). These devices allow officers to look, very stealthily, through walls comprised of common construction materials. The devices can penetrate reinforced concrete, concrete block, sheetrock, brick, wood, and wood composites. Their ability may be compromised if the walls are constructed of solid metal or are thicker than normal. The devices use UWB technology to sense motion behind the wall. When the device senses motion, an image appears as a blip on the equipment’s screen. UWB technology is effective because the suspect is not aware of it.