How does it work?

There are many different varieties of UWB, each suited to a different application. For example, much can be read about OFDM UWB, which is a complex implementation optimized for high speed, short range data links, and is being deployed in wireless USB products. Locating objects, however, requires it's own specialized approach, which can best be described as low duty cycle, short pulse UWB.

When using UWB to locate objects, it is preferable to use short pulses rather than a more complex waveform. The reason is simple: locating objects means measuring the time of arrival of signals, and that can be done most accurately if the signal all arrives at the same time. That's the same thing as saying that the signal needs to be very short.

Additionally, a low duty cycle is desired, which means that the pulses are short, but the space between them is large. Again, the reason is simple: it's better that you don't have many pulses arriving at the receiver at the same time - much better to space them apart a little.

Short pulse, low duty cycle transmitters can be as simple as fast switching diodes with filter networks, or as complex as silicon based digital pulse synthesizer driven by precision timing logic. Time Domain manufactures both types, each being best suited to different applications.

UWB receivers are the key to performance, and also come in many varieties. Time Domain focuses on low duty cycle, short pulse UWB and builds receivers accordingly. There is still much variation in implementation, however, and Time Domain currently fields three different receiver technologies, with a fourth nearing completion, and a fifth on the drawing board. Each of these is a specific balance of performance, cost, power consumption and size to achieve any given set of requirements. At one end, cost effective tracking systems aimed at asset and people tracking are well served by non-coherent receivers, whereas at the other, enabling multifunction unattended ground sensors for intruder tracking, classification and identification, a highly coherent form of UWB is preferred.