Paper # 1569100825 Submitted to IEEE 2008 Sarnoff Symposium 1 Abstract—This paper presents a continuous pulse ultra- wideband (or C-UWB) UWB data link exploiting the spectral properties of “truncated sine waves.” A truncated sine wave is a sine wave of finite duration – typically a low integer multiple number of periods. This paper further explores truncated sine wave pulses and presents several straightforward RF architectures suitable for implementing C-UWB systems. Finally, this paper presents results from a proof-of-concept C-UWB data link operating at 135Mb/s. C-UWB has a natural frequency diversity since each pulse occupies the entire UWB bandwidth. Index Terms—UWB, short pulse I. INTRODUCTION n 2002, the Federal Communications Commission (FCC) authorized UWB systems to operate in the 3.1-10.6GHz band. [1] Since then the European Community have issued a decision to implement UWB [2] based on the ITU-R Report and Recommendation [3] on UWB, and national bodies have implemented rules for UWB technology. [4] UWB systems offer outstanding data throughput with data rates of 100Mb/s up to 1,350Mb/s. UWB system development has been retarded by the widespread and mistaken impression that UWB systems require complex implementations and custom integrated circuit designs beyond the means of all but the best capitalized companies and institutions. To the contrary, a high data rate UWB link may be constructed from commonly available, commercial off-the-shelf components. This paper presents a proof-of-concept 950Mb/s UWB data link based on a “Continuous Pulse Ultra-wideband” (or C- UWB) architecture. C-UWB systems achieve spectral spreading and high data rates by modulating a carrier wave in such a way that an individual “chip” involves only a low integer number of cycles of the carrier wave and its optionally associated harmonics. For instance one can apply “whitened” or “pseudo-noise” (PN) encoded data at 950Mchips/s to a synchronized 3.8GHz carrier (fourth harmonic or four times the data rate). This C-UWB concept is the subject of both issued and pending patents [5, 6, 7, 8, 9]. Manuscript received February 1, 2008; revised April 3, 2008. This paper describes work the authors performed while employed by the Time Domain Corporation in 2002. H. G. Schantz is with Q-Track Corporation, Huntsville, AL 35816 USA (phone: 256-489-0075; fax: 256-704-6002; e-mail: h.schantz@ ieee.org). K. Siwiak, is with TimeDerivative, Inc., Coral Springs, FL, 33077 USA (e- mail: kai@timederivative.com). T. Janik is with Miltec Systems, Huntsville, AL 35806 USA (e-mail: tjanik@miltecsystems.com). -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 t HTL -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1 THtL Truncated Sine Signal 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 f -27 -24 -21 -18 -15 -12 -9 -6 -3 0 »FHfL» 2 Fig. 1. A truncated sine wave of order n = 2 with carrier frequency f C = 4 (left) and PSD of truncated sine signals with center frequency f C = 4 and n = 1, 2,…,6 (right). II. TRUNCATED SINE WAVES A. Defined C-UWB systems rely on the spectral properties of “truncated sine waves.” A truncated sine wave is a signal comprised of low integer numbers of complete cycles of some underlying carrier signal at a fixed frequency. One of us addressed the concept of “truncated sine signals” elsewhere [10], a presentation on which the present discussion draws. Low side lobe envelopes for truncated sine-wave pulse envelopes are described in [11], and appear in an IEEE 802 standard [12]. Henning Harmuth provided the earliest discussion of truncated sine waves known to the authors [13]. In the time domain, a truncated sine wave signal is: ()    < < = else nT t t f t T C 0 0 2 sin 0 π (1) where f C is the carrier frequency, T 0 is the period of the carrier and n is a (typically low) integer. Figure 1 shows a truncated sine wave signal of order n = 2 with carrier frequency f C = 4. B. Spectral Properties A sine wave of infinite time duration is infinitesimally narrow in frequency. As the sine wave time duration becomes increasingly short, its instantaneous spectral content spreads in frequency. Applying the Fourier Integral Theorem yields an analytic expression for the spectral density of a truncated sine wave: ( ) ( )( ) C C C c c f f f f f f jn f n f f F + −               − − = π π 2 2 exp 1 2 (2) Figure 2 shows the power spectral density (PSD) of the family of truncated sine waves with carrier frequency f C = 4. A first order truncated sine signal has a remarkably broad spectrum with a relative bandwidth on the order of 100%. Sidelobe levels converge to about –13dB for relative low order signals allowing removal of sidelobes to meet a desired spectral mask. Proof-of-Concept C-UWB Data Link Hans G. Schantz, Kazimierz Siwiak, and Tad Janik, Senior Members, IEEE I