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The Effects of SAW Nonidealities on a High-Speed Chirp Spread Spectrum Communications System

J. Pinkney, A.B. Sesay, S. Nichols
Wireless 99 Proceedings, Calgary, AB, pp. 207-213, July 12-14, 1999

One of the major advantages that Chirp Spread Spectrum (CSS) has over other spread spectrum techniques is its ease of implementation. CSS is an analog spreading technique which uses compact Surface Acoustic Wave (SAW) filters to perform the necessary signal processing. The physical nature of the SAW device creates its own problems, however, since second order effects inherent in the SAW can generate unwanted spurious signals. In this paper, we investigate the impact of these second order SAW effects on the performance of a CSS system. In particular, degradation caused by phase mis-matching, triple transit, and electromagnetic feed-through are investigated on a prototype indoor high-speed CSS system. Of these three, electromagnetic feed-through is shown to have the most debilitating effect. A cancellation technique is introduced which reduces unwanted signals produced which reduces unwanted signals produced by electromagnetic feed-through (EMFT) to acceptable levels.

CONTACTS: John Pinkney, Abu Sesay, Spence Nichols
SUBJECTS: Modulation and Decoding, RF Circuits and Systems
TYPE: Conference Publication
PUBLISHED: 1999

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