American company Time Domain has announced SoldierVision, a surveillance device that works through walls. It's one of the first products to use Time Domain's single-chip PulsON wireless technology, which also has applications for networking, personal radars and other new commercial areas. SoldierVision will let troops on the ground detect and locate personnel hiding in buildings or trapped under rubble; it is a small, handheld unit that can see through multiple walls at a range of up to 30 feet and can return both the number and location of people. PulsON is unlike normal wireless systems: instead of transmitting a steady carrier that's modulated with data, it sends a low-power series of sub-nanosecond pulses over a very wide range of frequencies. The receiver pieces together the signal by ultra-precise timing of these pulses. Small disturbances in timing caused by reflections from physical objects can also be detected and analysed, making a very precise, low power radar system. Data rates of up to 100Mbps are also possible, although most work has gone into radar systems like SoldierVision. The technology, also known as ultra wide band (UWB) or pulse radio, is currently going through approval in the US. This is taking longer than normal, as the regulatory framework is set up for carrier-based transmitters working within preset bands. UWB doesn't fit into this model, and there are worries that it may interfere with GPS positioning systems and other existing radio spectrum users. However, the company says that because it operates at such low power it is normally well below the normal background noise already present on all frequencies -- however, this also leads to problems in testing and analysing products for approval. In the UK, the Radiocommunications Agency has commissioned a study of how UWB will work with existing services, which concluded that reasonable densities of use would normally not cause conflicts. However, the RA does not as yet have a way of licensing such devices: any potential products would have to go through a lengthy process to establish a legal framework for this. Time Domain has been going for more than a decade as the main driving force behind UWB. Investors include Sony, telco US West, Siemens, Marconi and others. It has consistently said that UWB's intrinsic qualities of very low power, high bandwidth, long range and secure operation make it ideal for domestic and business applications, and Sony has said it expects to produce devices using UWB within three years. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the ZDNet news forum. Let the editors know what you think in the Mailroom. And read other letters.