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US 3,943,509 AGranted
Navigation aiding systems with one-way ranging and two-way synchronization
AssigneeElliott Brothers (London) Limited
InventorDavid Graham Pudsey
Life of this patent
Estimating the term…
Abstract
A navigation aiding system primarily for aircraft consists of a number of spaced apart ground stations. A ranging signal is transmitted to each of a number of aircraft in turn in response to received interrogation signals. The system allows a clock carried by each aircraft to be accurately synchronised with a master clock on the ground to permit the range to be measured precisely.
Claims11
In a system for aiding navigation, the combination of:
- a plurality of moving craft, each including transmitter means for transmitting an interrogation signal only once and at a fixed time within a particular time slot, which fixed time establishes an epoch for each craft which may differ from a master epoch, each craft transmitting during a different time slot within the master epoch;
- at least one fixed station, including transmitter means for transmitting ranging signals at fixed times uniquely to define said master epoch and each time slot within it, and for transmitting a synchronizing signal within each time slot only in response to an interrogation signal;
- and
- means at each craft for adjusting the time of transmission of each interrogation signal in response to said synchronizing signal, whereby the epoch established by each craft is adjusted to coincide in time with said master epoch, there being n time slots in each epoch whereby n moving craft may associate with the system.
1 more element
In a navigation aiding system, the combination of:
- a relatively fixed station having a master clock associated therewith, transmitter means connected with said master clock for transmitting ranging signals at predetermined times, receiver means for receiving an interrogating signal from a craft, and means interconnecting said receiver means and said transmitter means for causing said transmitter means to transmit a time synchronizing signal at a predetermined time in advance of a second fixed reference time of the master clock equal to the time difference between a first fixed reference time of the master clock and receipt of the interrogating signal from the craft;
- and
- a craft-carried system including an adjustable clock to be synchronized with said master clock, craft receiver means for receiving said ranging signals and said time synchronizing signal, craft transmitter means connected with said adjustable clock for transmitting said interrogating signal at that time of said adjustable clock theoretically corresponding to said first fixed reference time, and means interconnecting said craft receiver means and said adjustable clock for adjusting said adjustable clock such that the time of receipt of said synchronizing signal is said second fixed reference time, whereby to synchronize the first and second fixed reference time, according to said adjustable clock to the corresponding fixed reference times of said master clock.
Dependencies are inferred from the claim text.