Balanced system for ranging and synchronization between satellite pairs
First Claim
1. A balanced ranging and synchronization (R &
- S) system for synchronizing a clock on a slave platform (S) to a master platform (M) and for measuring the distance between M and S comprising;
an M clock, positioned on M, for generating an M clock output signal;
an S clock, positioned on S, for generating a S clock output signal;
M signal transmitting means on M, interconnected with said M clock, for transmitting an M timing signal in response to a predetermined M clock output signal;
S signal transmitting means on S, interconnected with said S clock, for transmitting an S timing signal in response to a predetermined S clock output signal;
M receiving means on M for receiving signals, including said S timing signal, from S;
S receiving means on S for receiving signals, including said M timing signal, from M;
M time difference measuring (TDM) means, interconnected with said M clock and said M receiving means, for measuring the M time difference between the transmission of said M timing signal and the reception of said S timing signal and for encoding said M time difference in an M time difference output signal;
S time difference measuring (TDM) means, interconnected with said S clock and said S receiving means, for measuring the S time difference between the transmission of said S timing signal and the reception of said M timing signal and for encoding said S time difference in an S time difference output signal;
S calculating means, interconnected with said S TDM means, said S receiving means and said S clock and with inputs including said M and S time difference output signals, for calculating the asynchronism between said M clock and said S clock, and for generating an S clock adjusting output signal for advancing or retarding said S clock so that said S clock is synchronized with said M clock.
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Accused Products
Abstract
A balanced ranging and synchronization (R&S) system for a master(M)-slave satellite pair including a clock, a transmitter, a receiver, a time difference measuring device and a calculating device on both M and S. Each satellite transmits timing signals synchronized to its clock, receives the timing signals from the other satellite and measures the time difference between the transmission and reception of the timing signals. The time difference measured on each satellite is then transmitted to the other satellite. The caluculating device on each satellite utilizes these time difference measurements to calculate the asynchronism between the clocks and the range between the satellites. Finally the S clock is adjusted so that the asynchronism is reduced to within predetermined limits.
105 Citations
17 Claims
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1. A balanced ranging and synchronization (R &
- S) system for synchronizing a clock on a slave platform (S) to a master platform (M) and for measuring the distance between M and S comprising;
an M clock, positioned on M, for generating an M clock output signal; an S clock, positioned on S, for generating a S clock output signal; M signal transmitting means on M, interconnected with said M clock, for transmitting an M timing signal in response to a predetermined M clock output signal; S signal transmitting means on S, interconnected with said S clock, for transmitting an S timing signal in response to a predetermined S clock output signal; M receiving means on M for receiving signals, including said S timing signal, from S; S receiving means on S for receiving signals, including said M timing signal, from M; M time difference measuring (TDM) means, interconnected with said M clock and said M receiving means, for measuring the M time difference between the transmission of said M timing signal and the reception of said S timing signal and for encoding said M time difference in an M time difference output signal; S time difference measuring (TDM) means, interconnected with said S clock and said S receiving means, for measuring the S time difference between the transmission of said S timing signal and the reception of said M timing signal and for encoding said S time difference in an S time difference output signal; S calculating means, interconnected with said S TDM means, said S receiving means and said S clock and with inputs including said M and S time difference output signals, for calculating the asynchronism between said M clock and said S clock, and for generating an S clock adjusting output signal for advancing or retarding said S clock so that said S clock is synchronized with said M clock. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- S) system for synchronizing a clock on a slave platform (S) to a master platform (M) and for measuring the distance between M and S comprising;
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8. A balanced ranging and synchronization (R &
- S) system for synchronizing a clock on a slave platform (S) to a master platform (M) and for measuring the distance between M and S comprising;
an M clock, positioned on M, for generating an M clock output signal; an S clock, positioned on S, for generating a S clock output signal; M signal transmitting means on M, interconnected with said M clock, for transmitting an M timing signal in response to a predetermined M clock output signal; S signal transmitting means on S, interconnected with said S clock, for transmitting an S timing signal in response to a predetermined S clock output signal; M receiving means on M for receiving signals, including said S timing signal, from S; S receiving means on S for receiving signals, including said M timing signal, from M; M time difference measuring (TDM) means, interconnected with said M clock and said M receiving means, for measuring the M time difference between the transmission of said M timing signal and the reception of said S timing signal and for encoding said M time difference in an M time difference output signal; S time difference measuring (TDM) means, interconnected with said S clock and said S receiving means, for measuring the S time difference between the transmission of said S timing signal and the reception of said M timing signal and for encoding said S time difference in an S time difference output signal; S calculating means, interconnected with said S TDM means said S receiving means and said S clock and with inputs including said M and S time difference output signals, for calculating the asynchronism between said M clock and said S clock;
according to the formula ##EQU2## and for calculating the time delay in the free space channel between M and S according to the formula;
##EQU3## where TiS is the true time when the predetermined S clock output signal is generated,TiM is the true time when the predetermined M clock output signal is generated, τ
iS is the time delay encoded in the S time difference output signal,τ
iM is the time delay encoded in said M time difference output signal;dr is the time equipment delay in the channel between S and M, df is the equipment delay in the channel between M and S, said S calculating means also for generating a clock adjusting output signal for advancing or retarding said S clock so that said S clock is synchronized with said M clock. - View Dependent Claims (9, 10, 11, 12, 13, 14)
- S) system for synchronizing a clock on a slave platform (S) to a master platform (M) and for measuring the distance between M and S comprising;
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15. A balanced ranging and synchronization (R &
- S) system for synchronizing the clock on a slave platform (S) to a master platform (M) and for determining the range between M and S where M and S are transfering high-rate digital data therebetween said R &
S system comprising;an M clock including an M stable oscillator and an M digital counter for providing an M digital clock output signal; and an S clock including an S stable oscillator and an S digital counter for providing an S digital clock output signal; M multiplexing means interconnected with said M clock for formatting an M digital data stream transmitted from M to S into frames where each frame is started by an M start-of-frame word (SOFiM) generated at time TiM by said M multiplexing means upon receiving a predetermined M digital clock output signal; S multiplexing means, interconnected with said S clock for formatting an S digital data stream transmitted from S to M into frames where each frame is started by an S SOFiS generated at time TiS by said S multiplexing means upon receiving a predetermined S digital clock output signal; M demultiplexing means for receiving said SOFiS transmitted from S, where said SOFiS is received at time (TiS)M ; S demultiplexing means for receiving said SOFiM transmitted from M where said SOFiM is received at (TiM)S ; M TDM means, interconnected with said M clock and said M demultiplexer means where said M TDM includes an M TDM digital clock for measuring the time interval between the time said SOFiM is generated, TiM, and the time said SOFiS is received, (TiS)M, where the output of said M TDM means is an M time difference word (TDW) and where said M TDW is included in the digital data stream transmitted from M to S; S TDM means, interconnected with said S clock and said S demultiplexer, where said S TDM includes an S TDM digital clock for measuring the time interval between the time said SOFiS is generated, TiS, and the time said SOFiM is received, (TiM)S, where the output of said S TDM means is an S time difference word (TDW) and where said S TDW is included in the digital data stream transmitted from S to M; S calculating means, interconnected with said S clock and with inputs including said S TDW from said S TDW means and said M TDW transmitted to S from M, for calculating the asynchronism between said S clock and said M clock and for calculating the intersatellite range; M calculating means, interconnected with said M clock and with inputs including said M TDW and said S TDW transmitted from S, for calculating the asynchronism and range, where said M and S calculating devices calculate the asynchronism according to the formula ##EQU4## and the time delay in the free space channel between M and S according to the formula, ##EQU5## where TiS is the true time when the predetermined S clock output signal is generated, TiM is the true time when the M predetermined M clock output signal is generated, τ
iS is the time delay encoded in the S TDW,τ
iM is the time delay encoded in the M TDW,dr is the equipment delay in the channel between S and M, df is the equipment delay in the channel between M and S, said S calculating means also for generating a clock adjusting output signal for advancing or retarding said S clock so that said S clock is synchronized with said M clock. - View Dependent Claims (16, 17)
- S) system for synchronizing the clock on a slave platform (S) to a master platform (M) and for determining the range between M and S where M and S are transfering high-rate digital data therebetween said R &
Specification