SYSTEMS, METHODS, AND TERMINALS FOR SYNCHRONIZATION OF SIGNAL TIMING BETWEEN A FIRST TERMINAL AND A SECOND TERMINAL
Systems, methods, and terminals for synchronization of signal timing between a first terminal and a second terminal are provided herein. The system and method includes transmitting a signal from a first terminal to a second terminal, the signal comprising a phase and a plurality of frames, receiving the signal at the second terminal, periodically inverting the phase of the signal at the frame interval to produce an inversion coded signal comprising at least one phase inversion point, transmitting the inversion coded signal from the second terminal to the first terminal, receiving the inversion coded signal at the first terminal, and determining transmission timing of the signal from the first terminal to the second terminal by measuring a timing discrepancy between the at least one phase inversion point and a start time of a next frame.
1 . A system for synchronizing signal timing of a signal comprising a phase and a plurality of frames, the system comprising:
a first terminal comprising a signal analyzing module;
a second terminal comprising a clock and an amplitude coding module, the clock outputting a clock signal at a frame interval;
wherein the first terminal is configured to transmit the signal to the second terminal;
wherein the second terminal is configured to receive the signal transmitted from the first terminal, periodically alter the amplitude of the signal at the frame interval using the amplitude coding module to produce an amplitude coded signal comprising at least one amplitude step discontinuity, and transmit the amplitude coded signal to the first terminal; and
wherein the first terminal is configured to receive the amplitude coded signal and determine signal transmission timing by measuring a discrepancy between the at least one amplitude step discontinuity and a beginning point of a next frame using the signal analyzing module.
2 . The system of claim 1 , wherein the first terminal is further configured to transmit an adjusted signal to the second terminal, the adjusted signal being the signal with a timing adjustment applied, and wherein the timing adjustment is determined from the transmission timing of the signal.
3 . The system of claim 2 , wherein the timing adjustment comprises delaying the transmission of the signal by an amount of time equal to the signal transmission timing.
4 . The system of claim 1 , wherein each frame comprises a length, and wherein the length is equal to the frame interval.
5 . The system of claim 1 , wherein the signal is a radio frequency (“RF”) signal.
6 . The system of claim 1 , wherein the second terminal is on an orbiting satellite.
7 . The system of claim 2 , wherein the signal is transmitted from the first terminal to the second terminal for a duration of time such that at least two full frames are transmitted before transmitting the adjusted signal.
8 . The system of claim 2 , wherein the first terminal comprises a Doppler estimation module configured to determine a Doppler shift between the signal and amplitude coded signal and apply a Doppler adjustment factor to the adjusted signal based on the determined Doppler shift.
9 . A method of synchronizing signal timing between a first terminal and a second terminal, wherein the second terminal comprises a clock, the clock outputting a clock signal at a frame interval, the method comprising:
transmitting a signal from the first terminal to the second terminal, the signal comprising a phase and a plurality of frames;
receiving the signal at the second terminal;
periodically altering, by the second terminal, the amplitude of the signal at the frame interval to produce an amplitude coded signal comprising at least one amplitude step discontinuity;
transmitting the amplitude coded signal from the second terminal to the first terminal;
receiving the amplitude coded signal at the first terminal;
determining transmission timing of the signal from the first terminal to the second terminal by measuring a timing discrepancy between the at least one amplitude step discontinuity and a start time of a next frame.
10 . The method of claim 9 , further comprising:
transmitting an adjusted signal from the first terminal to the second terminal, the adjusted signal being the signal with a timing adjustment applied, and wherein the timing adjustment is determined from the transmission timing of the signal.
11 . The method of claim 10 , wherein the timing adjustment comprises delaying the transmission of the signal by an amount of time equal to the signal transmission timing.
12 . The method of claim 9 , wherein each frame of the signal comprises a length, and wherein the length is equal to the frame interval.
13 . The method of claim 9 , wherein the signal is a radio frequency (“RF”) signal.
14 . The method of claim 9 , wherein the second terminal is on an orbiting satellite.
15 . The method of claim 10 , wherein the signal is transmitted from the first terminal to the second terminal for a duration of time such that at least two full frames are transmitted before transmitting an adjusted signal.
16 . The method of claim 9 , further comprising determining a Doppler shift between the signal and amplitude coded signal and applying a Doppler adjustment factor to the signal based on the Doppler shift determination.
17 . The method of claim 10 , wherein the signal is transmitted from the first terminal to the second terminal for a duration of time such that at least 2 frames are transmitted before transmitting an adjusted signal.
18 . The method of claim 17 , wherein frames are signal time slots.