Importance

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Abstract

A modulation method, applicable for augmentation of present art modulated signals. The method, for communicating data from a transmitter to a receiver, is based on periodical burst transmissions, set at a nominal timing, of signals which are either pure carriers or already modulated by data (e.g. ASK, FSK, PSK). Knowing the transmission timing and assessing the propagation delay, the receiver can estimate the nominal reception timing of these periodical transmissions. Modifying the nominal timing of a transmission, by a specific time period, is used to communicate a symbol between the transmitter and the receiver, according to a predefined encoding table which associates between a symbol and a unique time period. According to one embodiment of the invention, the transmitter is a distress radio beacon, configured to report its position upon activation, in periodical data burst transmissions, to ground stations through satellites. The present method is used to augment this report, complying with the present beacon specifications, yet providing a finer resolution of the reported coordinates. According to one embodiment, the position resolution is improved approximately from 125 to 8 meters.

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First Claim