** Early ultrawideband (UWB) systems were developed for military surveillance use because they could "see through" trees and beneath ground surfaces.
A traditional UWB transmitter works by sending billions of narrow pulses (often in the picosecond range (1/1000th of a nanosecond) across a very wide bandwidth (several GHz). The corresponding receiver then intercepts a special pulse sequence sent by the transmitter enabling it to be able to translate the received pulses back into usable data.
The Federal Communications Commission (FCC) and ITU-R now define UWB as having a spectrum that occupies a bandwidth greater than 20% of the center frequency, or has a bandwidth of at least 500 MHz. Note that even though the UWB bandwidth is considered very wide, the UWB transmission still must stay within a defined spectral bandwidth. In early 2002, the FCC give users permission to deploy low-powered UWB systems within 3.1 to 10.6 GHz. The maximum allowable power spectral density for UWB transmission of 41.3 dBm/MHz corresponds to approximately 0.5 mW of average transmit power when the entire 3.1-10.6 GHz band is used.
UWB is a wireless technology that is designed for short-range, personal area networks (PANs). UWB is also used for radar imaging, precision positioning and tracking technology.
There has been concern regarding the possible interference of narrowband and UWB signals that share the same spectrum. Historically, the only pulsed radio technology was spark gap transmitters (banned due to excessive interference). The difference between UWB and spark-gap transmitters is that UWB utilizes a much lower power.
The UWB/interference issue was covered in the proceedings that led to the adoption of the FCC rules in the US, and also in various UWB-related ITU-R meetings that led to the ITU-R Report and Recommendations on UWB technology. It was determined that common equipment (e.g., hair dryers) emit impulsive noise. Because of these findings, the argument was successfully made that the noise floor would not be raised excessively by wider deployment of wideband low power transmitters.
Title 47 - Telecommunication, Chapter 1 - Federal Communications Commission, Part 15 - Radio Frequency Devices, Technical Requirements Applicable to All UWB Devices (.pdf format), Section 15.521,10-1-05 Edition.
Common UWB Terms (Terms are defined in Wikipedia http://en.wikipedia.org/wiki/ ]
UWB Technical Articles
