Method of telecommunication via satellite and systems using this method

Claim 1

A method of telecommunication via a stationary active satellite, for transmitting respective messages to a plurality n of airborne receivers through said satellite, said method comprising the following steps: processing said messages and modulating them respectively on separate carriers having separate frequencies to which said receivers are respectively tuned to obtain successively and periodically n modulated carrier samples according to a time division multiplex transmission mode; transmitting said samples through said satellite towards said airborne receivers, the period spacing between and the duration of said samples being determined such, that the samples having a given carrier frequency are received directly on an airborne receiver tuned on said frequency at time intervals beyond those at which occurs reception of said samples having said carrier frequency after being reflected from ground towards said receiver; and making inoperative by time selection the reception on board beyond the intervals of direct reception of samples having the carrier frequency on which is tuned the corresponding airborne receiver.

Claim 2

A method of telecommunication via a stationary active satellite, for transmitting respective messages to a plurality n of airborne receivers through said satellite, said method comprising the following steps: processing said messages and modulating them respectively on separate carriers having separate frequencies to which said receivers are respectively tuned to obtain successively and periodically n modulated carrier samples according to a time division multiplex transmission mode; transmitting said samples through said satellite towards said airborne receivers, the period spacing between and the duration of said samples being determined such, that the samples having a given carrier frequency are received directly on an airborne receiver tuned on said frequency at time intervals beyond those at which occurs reception of said samples having said carrier frequency after being reflected from ground towards said receiver; and making inoperative by time selection the reception on board beyond the intervals of direct reception of samples having the carrier frequency on which is tuned the corresponding airborne receiver.

Claim 6

A method of telecommunication via a stationary active satellite for transmitting respective messages to a plurality n of airborne receivers, said method comprising the following steps: splitting each message into equal sections of duration T; processing each station by sampling, digital coding and pulse compression to obtain a modulating signal of duration at most equal to T/n; modulating a UHF wave with n successive modulating signals corresponding respectively to a section of a said n messages to produce a time-division multiplex transmission signal having said value T as a period, said UHF wave having n separate carrier frequencies attributed respectively to said n messages; transmitting said UHF modulated wave through said satellite to a determined operational zone for providing n simultaneous links with the n airborne receiver stations, respectively; receiving said UHF wave at said airborne receivers; filtering the received signals, each airborne receiver being tuned at one of said separate frequencies; making inoperative by time-selection the reception on board beyond the intervals of direct reception of signals of the link in question having the carrier frequency to which the corresponding airborne receiver is tuned, said time-selection having a duration at most equal to the valve T/n and recurring with the period T, said time modulation signal duration and said period T being determined such that the indirect reception of signals of the link having said carrier frequency, after being reflected from ground toward said carrier frequency, after being reflected from ground toward said receiver, occurs at time intervals beyond the direct reception of said message signal, the time interval of indirect reception being determined in relation to the altitude range of said airborne station and to the elevation angle range of said satellite in said operational zone; and processing said filtered and time-selected received signals to reproduce at said receiving station the message transmitted by the link.

Claim 7

A method of telecommunication via a stationary active satellite for transmitting respective messages to a plurality n of airborne receivers, said method comprising the following steps: splitting each message into equal sections of duration T; processing each station by sampling, digital coding and pulse compression to obtain a modulating signal of duration at most equal to T/n; modulating a UHF wave with n successive modulating signals corresponding respectively to a section of a said n messages to produce a time-division multiplex transmission signal having said value T as a period, said UHF wave having n separate carrier frequencies attributed respectively to said n messages; transmitting said UHF modulated wave through said satellite to a determined operational zone for providing n simultaneous links with the n airborne receiver stations, respectively; receiving said UHF wave at said airborne receivers; filtering the received signals, each airborne receiver being tuned at one of said separate frequencies; making inoperative by time-selection the reception on board beyond the intervals of direct reception of signals of the link in question having the carrier frequency to which the corresponding airborne receiver is tuned, said time-selection having a duration at most equal to the valve T/n and recurring with the period T, said time modulation signal duration and said period T being determined such that the indirect reception of signals of the link having said carrier frequency, after being reflected from ground toward said carrier frequency, after being reflected from ground toward said receiver, occurs at time intervals beyond the direct reception of said message signal, the time interval of indirect reception being determined in relation to the altitude range of said airborne station and to the elevation angle range of said satellite in said operational zone; and processing said filtered and time-selected received signals to reproduce at said receiving station the message transmitted by the link.

Claim 8

A method of telecommunication via a stationary active satellite comprising the following steps: splitting each message into equal sections of duration T; processing each section by sampling, digital coding and pulse compression to obtain a modulating signal of duration at most equal to T/n; T/n; modulating a UHF wave with n successive modulating signals corresponding respectively to a section of said n messages, to produce a time-division multiplex transmission signal having said value T as a period, said UHF wave having a number m less than n separate frequencies successively attributed to the first m modulating signals respectively and recurring for the second m modulating signals and so on during each period; transmitting said UHF modulated wave through said satellite to a determined operational zone for providing n simultaneous links with the n airborne receiver stations respectively; receiving said UHF wave at said airborne receivers; filtering the received signals, each airborne receiver being tuned to one of said separate frequencies; making inoperative by time-selection, the reception on board beyond the intervals of direct reception of signals of the link in question having the carrier frequency to which the corresponding airborne receiver is tuned, said time-selection having a duration at most equal to the value T/n and recurring with the period T, said time modulating signal duration and said period Tbeing determined such that the indirect reception of signals of a link having said carrier frequency after being reflected from ground towards said receiver occurs at time intervals beyond the direct reception of said message signal, the time interval of indirect reception being determined in relation to the altitude range of said airborne station and to the elevation angle range of said satellite in said operational zone, said period T being an entire multiple at least equal to twice the time interval between the initial time of direct reception of a section and the final time of indirect reception of the said section, the carrier frequencies distributed in a first time interval of said period being redistributed in the same order for the second following equal time interval, and so on; and processing said received signals filtered and time-selected to reproduce at said receiving station the message transmitted by the link.

Claim 9

A method of telecommunication via a stationary active satellite comprising the following steps: splitting each message into equal sections of duration T; processing each section by sampling, digital coding and pulse compression to obtain a modulating signal of duration at most equal to T/n; T/n; modulating a UHF wave with n successive modulating signals corresponding respectively to a section of said n messages, to produce a time-division multiplex transmission signal having said value T as a period, said UHF wave having a number m less than n separate frequencies successively attributed to the first m modulating signals respectively and recurring for the second m modulating signals and so on during each period; transmitting said UHF modulated wave through said satellite to a determined operational zone for providing n simultaneous links with the n airborne receiver stations respectively; receiving said UHF wave at said airborne receivers; filtering the received signals, each airborne receiver being tuned to one of said separate frequencies; making inoperative by time-selection, the reception on board beyond the intervals of direct reception of signals of the link in question having the carrier frequency to which the corresponding airborne receiver is tuned, said time-selection having a duration at most equal to the value T/n and recurring with the period T, said time modulating signal duration and said period Tbeing determined such that the indirect reception of signals of a link having said carrier frequency after being reflected from ground towards said receiver occurs at time intervals beyond the direct reception of said message signal, the time interval of indirect reception being determined in relation to the altitude range of said airborne station and to the elevation angle range of said satellite in said operational zone, said period T being an entire multiple at least equal to twice the time interval between the initial time of direct reception of a section and the final time of indirect reception of the said section, the carrier frequencies distributed in a first time interval of said period being redistributed in the same order for the second following equal time interval, and so on; and processing said received signals filtered and time-selected to reproduce at said receiving station the message transmitted by the link.