Systems and methods for synchronizing time, frequency, and phase among a plurality of devices

A system for synchronizing the clocks of a plurality of platforms that includes a first platform and a second platform, the system including:

• a first platform and a second platform that is movable relative to the first platform, each of the first and second platform comprising:
• (a) wireless communications module;
• (b) a clock module that provides a fundamental clock having a fundamental frequency and a fundamental phase and a baseband clock having a baseband frequency having a baseband phase, wherein the baseband clock is based on the fundamental clock;
• (c) a transceiver for providing a radio-frequency (RF) signal having an RF clock that is based on the fundamental clock and the baseband clock;
• (d) a processor;
• and
• (e) a clock-control module that is operative for controlling at least one of the fundamental frequency, the fundamental phase, the baseband frequency, and the baseband phase;
• and
• wherein the processor of each platform is operative for determining:
• (i) estimating a baseband frequency offset between the respective fundamental frequencies of the first and second platforms, the estimated baseband frequency offset being based on a round-trip RF signal having a first leg transmitted from the first platform to the second platform and a second leg transmitted from the second platform to the first platform, the round-trip RF signal including a carrier phase slope on each of the first and second legs;
• (ii) computing a derived code phase slope from the carrier phase slope that is based on the fundamental frequency, and the baseband frequency for each platform;
• (iii) computing a fractional baseband offset between the respective baseband clocks of the first and second platforms, the fractional baseband offset being based on the number of elapsed baseband clock cycles and the code phase for each of the first and second platforms;
• and
• (iv) controlling at least one of the fundamental frequency, the fundamental phase, the baseband frequency, and the baseband phase of its respective platform based on a combination of the respective baseband frequency offset and fractional baseband offset of its respective platform.

A method for synchronizing the clocks of a plurality of platforms that includes a first platform and a second platform, the method including:

• (i) at each of the first and second platforms, generating a fundamental clock having a fundamental frequency and a fundamental phase and a baseband clock having a baseband frequency and a baseband phase;
• (ii) estimating a baseband frequency offset between the respective fundamental clocks of the first and second platforms, the estimated baseband frequency offset being based on a round-trip RF signal having a first leg transmitted from the first platform to the second platform and a second leg transmitted from the second platform to the first platform, the round-trip RF signal including a carrier phase slope on each of the first and second legs;
• (iii) computing a derived code phase slope from the carrier phase slope that is based on the fundamental clock and the baseband clock for each platform;
• (iv) computing a fractional baseband offset between the respective baseband clocks of the first and second platforms, the fractional baseband offset being based on the number of elapsed baseband clock cycles and the code phase for each of the first and second platforms;
• and
• (v) controlling at least one of the fundamental frequency, the fundamental phase, the baseband frequency, and the baseband phase of its respective platform based on a combination of the respective baseband frequency offset and fractional baseband offset of its respective platform.