Ico Services Limited

Inmarsat Limited

Charles Chambers

Paul Chambers

Gunnar Arvid Bjornstrom

In a mobile communications system, a message is sent to a mobile terminalwhich transmits an acknowledgement signal if the message is received. If the systemdoes not detect an acknowledgement signal, it transmits a high margin notification signal to the mobile terminalto notify the terminal that an attempt was made to send the message. When the mobile terminalhas received a notification signal and subsequently comes within range of lower margin signals from the system, it sends a registration signal to the system. The system may then retransmit the message to the mobile terminal

High margin notification method and apparatus

In a mobile communications system , a message is sent to a mobile terminal which transmits an acknowledgement signal if the message is received. If the system does not detect an acknowledgement signal, it transmits a high margin notification signal to the mobile terminal to notify the terminal that an attempt was made to send the message. When the mobile terminal has received a notification signal and subsequently comes within range of lower margin signals from the system, it sends a registration signal to the system. The system may then retransmit the message to the mobile terminal

In a preferred satellite (,) communications environment, spread spectrum communications, under extremes of digital message readability, is established for a digital message,by division into smaller elements W(0)-W(C&minus;1) which are transmitted in turn, each multiplied for logical inversion or non-inversion, by the individual, sequential digits of a preferred binary polynomial,, being either a PN polynomial, an m-polynomial, or simply displaying alternate logical ones and zeroes. The preferred polynomial may be used convey an alternative polynomial for better reception of a subsequent digital message.

Digital messaging method and apparatus

In a satellite position fixing system, where an earth station,communicates with a satellite 10 which, in turn, communicates with selectable ones out of a plurality of user terminals,whose position, on the surface of the earth,, is measured, the accuracy of measurement of the position of the satellite,is improved by using all of the user terminals,as further triangulation points, the improved position being incorporated in further user terminal,position determinations, and so on to create a cumulative improvement. Weighting is applied so that user terminals,with large errors in triangulation are given small significance and those with small errors are given great significance.

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Cambridge, United Kingdom

Charles Chambers