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1. (WO2001001648) CHIRP WAVEFORM DECODING SYSTEM

Pub. No.:    WO/2001/001648    International Application No.:    PCT/GB2000/001830
Publication Date: Fri Jan 05 00:59:59 CET 2001 International Filing Date: Sat May 13 01:59:59 CEST 2000
IPC: H04L 27/10
H04L 27/148
H04L 27/156
H04B 1/69
Applicants: ANGLIN, Richard, L.
POWELL, Stephen, David
Inventors: ANGLIN, Richard, L.
Title: CHIRP WAVEFORM DECODING SYSTEM
Abstract:
Before information is extracted from incoming chirp radio frequency waveforms (28), they are subjected to noise removal, e.g. by a Kalman fitter (40), amplitude normalization and synchronization. The nature of the information-extraction step depends upon the particular form of chirp waveform (28) received. In one method, fo is subtracted from the waveform (28) to down convert it to a series of Up and Down pulses, or alternatively Up-Down and Down-Up pulses, which are supplied to a frequency-to-voltage converter (56); the output of the converter is in the form of triangular pulses which are then differentiated (60) to produce positive or negative square pulses. In another proposed method the information-extraction step involves determining the zero crossings of received chirp radio frequency waveforms; an alternative method involves integrating and a further method involves a delay of the received chirp signal.