Detection of an electromagnetic signal
First Claim
1. A signal detection system comprising an electromagnetic signal detector having a limited on-time for detecting receipt of electromagnetic signals, at least two optical paths each arranged to receive an electromagnetic signal from the same nominal direction in space and to transmit any received signal towards said signal detector, an optical time delay operative within one of said optical paths to delay transmission of said received signal towards said signal detector, and said optical time delay is selected to extend the operational range of said signal detector by compressing the real time during which said received signal can be received into the shorter on-time of said signal detector.
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Abstract
A signal detector system (10) comprises a single signal detector (11) having a limited on-time during which any received electromagnetic signal can be assessed. The signal detector (11) receives electromagnetic signals from a single direction in space (D) through a single optical fibre (12), a signal splitter 13 which splits the collected signal between three optical paths (20, 30 and 40), and a signal combiner (14) which combines the portions of the signal transmitted by the three optical paths (20, 30 and 40) and transmits the combined signal to a signal detector input (15). Each of the optical paths (20, 30 and 40) includes a respective optical delay (21, 31 and 41) designed to delay transmission of any received signal towards the signal detector (11). In this manner the signal detector (11) will receive any signals that arrived at the optical fibre (12) during three separate periods of time.
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Citations
19 Claims
- 1. A signal detection system comprising an electromagnetic signal detector having a limited on-time for detecting receipt of electromagnetic signals, at least two optical paths each arranged to receive an electromagnetic signal from the same nominal direction in space and to transmit any received signal towards said signal detector, an optical time delay operative within one of said optical paths to delay transmission of said received signal towards said signal detector, and said optical time delay is selected to extend the operational range of said signal detector by compressing the real time during which said received signal can be received into the shorter on-time of said signal detector.
- 17. A method of detecting an electromagnetic signal travelling from a nominal direction in space, comprising splitting the signal into a plurality of paths, delaying the passage of the split signal along some of said paths, and detecting the portion of the signal that leaves each of said paths at substantially the same time.
Specification