Conjugate-phase, remote-clock synchronizer

• US 4,368,987 A
• Filed: 06/25/1980
• Issued: 01/18/1983
• Est. Priority Date: 06/25/1980
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Waters, William M.
• Primary Examiner(s): Miska, Vit W.
• Application Number:
  US06/163,001
• Time in Patent Office: 937 Days
• Field of Search: 368/46, 368/47, 368/49, 368/51, 73/6, 375/107, 375/118
• US Class Current: 368/46
• CPC Class Codes: G04G 7/02 by radio

Abstract

A method for synchronizing a master clock and a remote slave clock which nominally has the same pulse frequency but may be out of time-phase comprising transmitting a master pulse to the slave, measuring the time delay, Δτ, between the received pulse and the nearest succeeding (in time) slave pulse, delaying the latter slave pulse by Δτ to provide a conjugate slave pulse, transmitting the conjugate pulse to the master station and measuring the time difference Δ between time of reception of the conjugate pulse and time of generation of the original master pulse. The time Δ is equal to twice the error between the master and slave pulses. The process can also be done at the slave station if the slave pulse is transmitted to the master and a conjugate-phase master pulse is retransmitted to the slave where the measurement is accomplished. The phase of the slave pulse can then be adjusted by Δ/2 to synchronize it with the master pulse.

Claims

1. A method for determining the time reading of a remote-station clock at a first clock station, each station having a clock producing a train of clock pulses, both trains having substantially the same frequency but being different in time phase by an amount Δ

t, the method comprising the steps of;

transmitting a clock pulse, called the originator pulse, from the first station to start the timing sequence;

receiving at the remote station the originator pulse and utilizing the received pulse to form a conjugate-phase pulse from the remote-station clock;

transmitting the conjugate-phase pulse to the first station and receiving it there;

measuring at the first station the time difference Δ

between the time of reception of the conjugate-phase pulse and the time of generation of the originator pulse; and

determining the difference in time phase Δ

t between the time reading of the remote-station clock and the first-station clock according to the relationship Δ

t=Δ

/2.

2. A method as set forth in claim 1, wherein:

said conjugate-phase pulse is produced by measuring the time, Δ

τ

, between time of reception of the originator pulse and time of generation of the immediately succeeding remote-station pulse and then adjusting the time of transmission of said immediately succeeding remote-station pulse so that transmission occurs at its time of generation plus Δ

τ

.

3. A method as set forth in claim 1, including the additional step of:

synchronizing the first-station clock with the remote-station clock by adjusting the time of generation of first-station clock pulses by an amount equal to Δ

t.

4. A method as set forth in claim 1, including the additional step of:

synchronizing the first-station clock with the remote-station clock by delaying the remote station clock by an amount equal to Δ

t.

5. The methods of claims 1 or 2 including the further step of:

synchronizing the clocks at the two stations by adjusting the time phase of the clock at the first-clock station by the value of Δ

/2.

6. A method for determining at a first-clock station the time reading of the clock at a remote second-clock station, the first and second clocks each transmitting a train of spaced pulses, the trains having substantially the same frequency but different time phases by an amount Δ

t, the method comprising;

transmitting a first clock pulse from the first station;

receiving the transmitted first-clock pulse at the second-clock station;

measuring at the second station the time duration, Δ

τ

, between reception of the first-clock pulse and generation of the immediately succeeding second-clock pulse;

generating a phase conjugate of the received first-clock pulse from the second clock;

transmitting the conjugate pulse;

receiving the conjugate pulse at the first-clock station;

measuring at the first-clock station the time, Δ

, between reception of the conjugate pulse and generation of the immediately first-clock pulse which started the measurement sequence; and

determining the time reading of the second-clock by correcting the time reading of the first clock by the value of Δ

/2=Δ

t.

7. A method for determining the time reading of a remote-station clock at a first clock station, each station having a clock producing a train of clock pulses, both trains having substantially the same frequency but being different in time phase by an amount Δ

t, the method comprising the steps of;

transmitting a first-clock pulse from the first-clock station;

receiving the transmitted first-clock pulse at the second-clock station;

measuring at the second-clock station the time delay, Δ

τ

, between reception of the first-clock pulse and generation of the immediately succeeding second-clock pulse;

delaying the time of the next second-clock pulse by an amount equal to the measured time, Δ

τ

;

transmitting the time-delayed second-clock pulse;

receiving the transmitted time-delayed pulse at the first-clock station;

measuring at the first-clock station the time, Δ

, between reception of the time-delayed pulse and generation of the first-clock pulse which started the measurement sequence; and

determining at the first-clock station the time reading of the clock at the second-clock station by adding the time, (Δ

/2)=Δ

t, to the reading of the clock at the first-clock station.

8. A method for determining at a master clock station the time reading of the slave clock at a remote slave clock station, the master and slave clocks each transmitting a train of spaced pulses, the trains having substantially the same frequency but different time phases, Δ

t_i, the method comprising the steps of;

transmitting a master clock pulse from the master station;

receiving the master pulse at a slave station;

measuring at the slave station the time duration, Δ

τ

, between reception of the master pulse and generation of the immediately succeeding slave clock pulse;

delaying said immediately succeeding a slave clock pulse to form the phase conjugate of the received master pulse;

transmitting the conjugate slave pulse;

receiving the conjugate slave pulse at the master station;

measuring at the master station the time, Δ

, between reception of the conjugate slave pulse and the generation of the master clock pulse which originated the measuring sequence; and

determining the time reading of the slave clock by correcting the time reading of the master clock pulse by the value of Δ

/2=Δ

t.

9. A method for determining at a master clock station the time reading of the slave clock at a remote slave station, the master and slave clocks each transmitting a train of spaced pulses, the trains having substantially the same frequency but different time phases, Δ

t_i, the method comprising the steps of;

transmitting a master clock pulse from the master station;

receiving the transmitted master clock pulse at the slave station;

measuring at the slave station the time delay, Δ

τ

, between reception of the master clock pulse and generation of the immediately succeeding slave clock pulse;

delaying said immediately succeeding slave clock pulse by an amount equal to the measured time, Δ

τ

;

transmitting the time-delayed slave clock pulse;

receiving the transmitted delayed slave clock pulse at the master station;

measuring at the master station the time, Δ

, between reception of the slave clock pulse and generation of the master clock pulse which originated the measuring sequence; and

determining at the master station the time reading of the slave clock by adding the time, Δ

/2=Δ

t, to the master clock reading.

10. A method for determining the time reading of a remote-station clock at a first clock station, each station having a clock producing a train of clock pulses, both training having substantially the same frequency but being different in time phase by an amount Δ

t, the method comprising the steps of;

transmitting a clock pulse, called the originator pulse, from the first station to start the timing sequence;

receiving at the remote station the originator pulse and utilizing the received pulse to form a conjugate-phase pulse from the remote-station clock, said conjugate-phase pulse being produced by measuring the time, Δ

τ

, between the time of reception of the originator pulse and the time of generation of the immediately succeeding remote-station pulse and then adjusting the time of transmission of said immediately succeeding remote-station pulse so that the transmission occurs at its time of generation plus Δ

τ

;

transmitting the conjugate-phase pulse to the first station and receiving it there; and

measuring at the first station the time difference Δ

between the time of reception of the conjugate-phase pulse and the time of generation of the originator pulse,

the time reading of the remote-station clock being different from that of the first-station clock by an amount equal to Δ

/2.

11. A method as set forth in claim 10, including the additional step of:

synchronizing the first-station clock with the remote-station clock by adjusting the time of generation of first-station clock pulses by an amount equal to Δ

/2.

12. A method as set forth in claim 10, including the additional step of:

synchronizing the first-station clock with the remote-station clock by delaying the remote station clock by an amount equal to Δ

/2.