Time-of-day tracking with INS input is described. In one embodiment, a
range rate and a range acceleration is generated from inertial navigation
system data received from a moveable platform (e.g. an airborne
platform). A time and frequency estimation filter receives the range
rate, the range acceleration and a timing-based error signal from a time
discriminator, and can then generate a time-of-day correction signal and
a frequency correction signal. A time-of-day generator receives the
time-of-day correction signal and generates a time-of-day correction, and
a clock frequency generator receives the frequency correction signal and
generates a frequency correction. The time discriminator receives a
satellite synchronization signal from a satellite, the time-of-day
correction from the time-of-day generator, and the frequency correction
from the clock frequency generator. The time discriminator initially
generates the timing-based error signal from the satellite
synchronization signal, and subsequently generates the timing-based error
signal from the time-of-day correction and the frequency correction to
synchronize the satellite with the moveable platform.