Appeal No. 2000-2085
Application No. 08/803,937
each of the satellites [S1, S2] to the object
being located. The object is typically a mobile
unit or other vehicle such as an aircraft [12']
having a communications terminal. The fixed
ground station signals, as transmitted to the
object, are referred to herein as forward
signals. The object receives these periodic
forward signals and measures the percent of
periodic phase offset between the two carrier
waveforms. The difference in phase between
these two carrier waveforms is due to one of the
signals traveling a longer path length via one
satellite than the other. The object transmits
a return signal [24' , 24b], after some1
arbitrary delay in which the amount [of] the
delay is not important nor required to be known,
containing the percent offset information. The
return signal is transmitted upon the same path
as the forward signal from the first satellite,
back to the fixed ground station.
In monitoring the received carrier periodic
signal through the first satellite, the object
performs functions that slave the clock standard
of the object to the reception of the periodic
signal. Thus the object clock standard is
offset in time from the fixed ground station
transmitted signal on account of the signal
propagation delay. The object is then allowed
to transmit the observed percent offset between
the two forward signals, starting at some
specific period in the future. The fixed ground
station then receives the return signal back
through the first satellite whenever it comes
back, but realizes the receipt of a message
starting with that specific period
identification number, or frame, has arrived
later than the current period being sent out on
According to the Ames specification, reference numeral 24’ in Figure 21
should be 24a’.
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