This paper presents a novel UWB communications system using double FM: a low-modulation index digital FSK followed by a high-modulation index analog FM to create a constant-envelope UWB signal. FDMA techniques at the subcarrier level are exploited to accommodate multiple users. The system is intended for low (1–10 kbps) and medium (100–1000 kbps) bit rate, and short-range WPAN systems. A wideband delay-line FM demodulator that is not preceded by any limiting amplifier constitutes the key component of the UWBFM receiver. This unusual approach permits multiple users to share the same RF bandwidth. Multipath, however, may limit the useful subcarrier bandwidth to one octave. This paper addresses the performance with AWGN and multipath, the resistance to narrowband interference, as well as the simultaneous detection of multiple FM signals at the same carrier frequency. SPICE and Matlab simulation results illustrate the principles and limitations of this new technology. A hardware demonstrator has been realized and has allowed the confirmation of theory with practical results.
This article is part of the series UWBState of the Art.
Principles and Limitations of Ultra-Wideband FM Communications Systems
1 Centre Suisse d'Electronique et de Microtechnique SA, Jaquet-Droz 1, Neuchâtel, CH-2007, Switzerland
2 National Semiconductor BV, Amplifier Design Europe, Delftech Park 19, Delft 2628 XJ, The Netherlands
3 Electronics Research Laboratory/DIMES, Faculty of Electrical Engineering, Mathematics and Computer Science (EEMCS), Delft University of Technology, Mekelweg 4, Delft 2628 CD, The Netherlands
EURASIP Journal on Advances in Signal Processing 2005, 2005:189150 doi:10.1155/ASP.2005.382
The electronic version of this article is the complete one and can be found online at: http://asp.eurasipjournals.com/content/2005/3/189150
|Received:||10 October 2003|
|Revisions received:||7 March 2004|
|Published:||17 March 2005|
© 2005 Gerrits et al.
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