Transmission of time referenced radio waves
AssigneeSociete d'Etudes, Recherches et Construction Electroniques (Sercel)
InventorsGeorges P. Nard, Daniel J. E. Bourasseau, Jean M. Rabian
Life of this patent
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Abstract
The invention relates to the radio-electrical transmission of accurate timing-mark signals. A space-diversity electrical connection is formed between a station having one single antenna and a station having two antennae and one of the stations is equipped with a receiver device which combines into one composite timing-mark signal the different repetitive timing-marks decoded and rectified from high-frequency signals which have traversed several spatial propagation paths. A common automatic gain control circuit weights the decoded and rectified timing marks according to a weighting which diminishes with the level of high frequency reception. Preferably the rectification of the timing marks is carried out non-linearly.
Claims22
A system for the radio-electrical transmission of a high-frequency signal carrying a timing-mark, comprising:
- (a) transmitter circuit means for generating a first high-frequency electrical signal carrying a basic timing-mark which is predetermined and repetitive;
- (b) a first antenna station coupled to said transmitter circuit means for transmitting waves corresponding to said first high-frequency electrical signal carrying said basic timing-mark;
- (c) a second antenna station remote from said first antenna station, one of said first and second antenna stations having at least two spaced-apart antennae so as to define at least two different propagation paths for high-frequency waves between said first and second antenna stations, said second antenna station comprising means for receiving said transmitted waves carrying said basic timing-mark after travel thereof over said at least two different propagation paths, and for delivering corresponding high-frequency electrical signals which carry received timing-marks, said received timing-marks being the same as said basic timing-mark but being shifted in time with respect to said basic timing-mark in dependence upon the travelling time of the waves over each of said different propagation paths;
- and
- (d) receiver circuit means coupled to said second antenna station for obtaining the received high-frequency electrical signals therefrom, said receiver circuit means comprising non-coherent combining means for
- (1) separately decoding, for each of the different propagation paths, the corresponding received high-frequency electrical signals carrying the timing-marks which are delivered by the second antenna station,
- (2) rectifying the separately decoded high-frequency electrical signals carrying the timing-marks in order to recover said timing-marks, and
- (3) non-coherently combining together the recovered said timing-marks into a composite timing-mark,
- whereby said composite timing-mark is more closely related to the travelling time of the waves between said first and second antenna stations than each of the recovered timing-marks individually.
Dependencies are inferred from the claim text.