【正文】 附錄二 英文資料及其翻譯The Foreign language datum of Ultra wideband technologyWhat is ultra wideband technology? First of all, the term ultra wideband is a relatively new term to describe a technology which had been known since the early 1960’s as carrierfree, baseband or impulse technology. The basic concept is to develop, transmit and receive an extremely short duration burst of radio frequency (RF) energy – typically a few tens of picoseconds (trillionths of a second) to a few nanoseconds (billionths of a second) in duration. These bursts represent from one to only a few cycles of an RF carrier wave. The resultant waveforms are extremely broadband, so much so that it is often difficult to determine an actual RF center frequency – thus, the term carrierfree. Early methods of signal generation utilized baseband (., nonRF), fast risetime pulse excitation of a wideband microwave antenna to generate and radiate the antenna’s effective impulse response. (More precisely, it is the antenna’s step response that is actually produced.) More modern UWB systems, such as those developed by MSSI, no longer utilize direct impulse excitation of an antenna because of the inability of such an approach to adequately control emission bandwidths and apparent center frequencies.[1]Ultra Wideband (UWB) systems transmit signals across a much wider frequency than conventional systems and are usually very difficult to detect. The amount of spectrum occupied by a UWB signal, . the bandwidth of the UWB signal is at least 25% of the center frequency. Thus, a UWB signal centered at 2 GHz would have a minimum bandwidth of 500 MHz and the minimum bandwidth of a UWB signal centered at 4 GHz would be 1 GHz. The most mon technique for generating a UWB signal is to transmit pulses with durations less than 1 nanosecond.[2]UWB is a wireless radio technology originally developed for secure military munications and radar that is now declassified. In the future, UWB will be ideally suited for transmitting data between consumer electronics (CE), PC peripherals, and mobile devices within short range at very high speeds while consuming little power. UWB technology has the capacity to handle the very high bandwidths required to transport multiple audio and video streams. This new technology operates at a level that most systems interpret as noise and, as a result, does not cause interference to other radios such as cell phones , cordless phones or broadcast television sets.[3]When was UWB invented and by whom?Tough question, but easy answer! There have been many claims to the honor。 however, Dr. Gerald F. Ross, currently President of ANRO Engineering, Inc., first demonstrated the feasibility of utilizing UWB waveforms for radar and munications applications back in the late 1960’s and early 1970’s. Gerry’s pioneering insight into the value and applications of this technology over 30 years ago has been instrumental in shaping UWB technology to the point it has reached today – with applications ready to meet market demands for highspeed wireless and precision radar/positioning applications. Gerry was recognized by the National Academy of Engineering for his efforts in ultra wideband technology, and elected a Member in 1995. MSSI has had the privilege of working with Dr Ross for many years.[1]How UWB works?A traditional UWB transmitter works by sending billions of pulses across a very wide spectrum of frequencies several GHz in bandwidth. The corresponding receiver then translates the pulses into data by listening for a familiar pulse sequence sent by the transmitter. Specifically, UWB is defined as any radio technology having a spectrum that occupies a bandwidth greater than 20 percent of the center frequency, or a bandwidth of at least 500 MHz.Modern UWB systems use other modulation techniques, such as Orthogonal Frequency Division Multiplexing (OFDM), to occupy these extremely wide bandwidths. In addition, the use of multiple bands in bination with OFDM modulation can provide significant advantages to traditional UWB systems.UWB39。s bination of broader spectrum and lower power improves speed and reduces interference with other wireless spectra. In the United States, the Federal Communications Commission (FCC) has mandated that UWB radio transmissions can legally operate in the range from GHz up to GHz, at a limited transmit power of 41dBm/MHz. Consequently, UWB provides dramatic channel capacity at short range that limits interference.[3]What are the advantages of UWB technology?Since UWB waveforms are of such short time duration, they have some rather unique properties. In munications, for example, UWB pulses can be used to provide extremely high data rate performance in multiuser network applications. For radar applications, these same pulses can provide very fine range resolution and precision distance and/or positioning measurement capabilities. In fact, multifunction architectures enpassing munications, radar and positioning applications have been developed.These short duration waveforms are relatively immune to multipath cancellation effects as observed in mobile and inbuilding environments. Multipath cancellation occurs when a strong reflected wave – ., off of a wall, ceiling, vehicle, building, etc. – arrives partially or totally out of phase with the direct path signal, causing a reduced amplitude response in the receiver. With very short pulses, the direct path has e and gone before the reflected path arrives and no cancellation occurs. As a consequence, UWB systems are particularly well suited for highspeed, mobile wireless applications. In addition, because of the extremely short duration waveforms, packet burst and time division multiple access (TDMA) protocols for multiuser munications are readily implemented.As bandwidth is inversely related to pulse duration ,the spectral extent of these Waveforms can