Scalable multi-source GPS signal distribution network

1. A method comprising:

receiving global positioning system signals from global positioning system receivers, the global positioning system receivers receiving the global positioning system signals from corresponding global positioning system satellites;

determining, using a selector circuit, a signal quality score of each received global positioning system signal based on a signal drift and a phase precision of the corresponding global positioning system signal;

for each signal quality score:

associating a source identification with the signal quality score, the source identification identifying a global positioning system satellite sending the global positioning system signal; and

storing the signal quality score and the associated source identification in non-transitory memory; and

selecting, using the selector circuit, one of the received global positioning system signals having the highest signal quality score and the source identification associated with the received global positioning system signal having the highest signal score.

2. A method comprising:

receiving global positioning system signals from global positioning system receivers, the global positioning system receivers receiving the global positioning system signals from corresponding global positioning system satellites;

determining, using a selector circuit, a signal quality score of each received global positioning system signal based on a signal drift and a phase precision of the corresponding global positioning system signal; and

selecting, using the selector circuit, one of the received global positioning system signals having the highest signal quality score,

wherein each global positioning system signal comprises a frequency signal component, a pulse per second signal component, and a time-of-day signal component.

3. The method of claim 2 , wherein the signal drift comprises a drift of the pulse per second signal component and a drift of the frequency signal component.

4. The method of claim 3 , further comprising determining the signal drift of a signal by calculating:

J i =g J ( J i F ,J i P )

wherein J i is a total drift of a signal, J i F is the frequency drift of a signal, J i P is the pulse per second drift of the signal, and g J is a function of the frequency drift and the pulse per second drift of the signal.

5. The method of claim 2 , wherein the phase precision comprises:

an offline measurement of a propagation delay of the pulse per second component of the corresponding global positioning system signal between the corresponding global positioning system receiver and the selector circuit; and

an online measurement of a relative phase offset of the pulse per second signal component, the relative phase offset determined based on a reference pulse per second reference signal.

6. The method of claim 5 , wherein the reference signal is the received pulse per second signal component received at the selector circuit or a signal generated by a high-precision high-frequency oscillator.

7. The method of claim 6 , further comprising determining the phase precision of the global positioning system signal by calculating:

D i =D i P −D i R

wherein D i is the phase precision of a signal, D i P is the offline measurement of the propagation delay of the pulse per second signal component between the corresponding global positioning system receiver and the selector circuit, and D i R is the online measurement of the relative phase offset of the pulse per second signal component.

8. The method of claim 7 , further comprising determining the signal quality score by calculating:

S i =g s (Δ D i , J i )

wherein S i is the signal quality score of a received signal, g s is a function for determining the signal quality score, and ΔD i is a convergence of a phase accuracy of the pulse per second signal component determined by calculating:

Δ D i =|D i −D m |

where D m is a median value of {D i }.

9. A method comprising:

receiving global positioning system signals from global positioning system receivers, the global positioning system receivers receiving the global positioning system signals from corresponding global positioning system satellites;

iterating through each of the global positioning system signals from the global positioning system receivers, and for each iteration receiving a primary signal comprising a currently selected global positioning system signal having a currently highest signal quality score and a secondary signal comprising the global positioning system signal of the corresponding iteration; and

after iterating through all of the global positioning system signals from the global positioning system receivers:

determining, using a selector circuit, a signal quality score of each received global positioning system signal based on a signal drift and a phase precision of the corresponding global positioning system signal; and

selecting, using the selector circuit, the global positioning system signal having the highest signal quality score as the primary signal.

10. The method of claim 9 , further comprising, at each iteration, receiving a source identification of the primary signal and a source identification of the secondary signal.

11. The method of claim 10 , further comprising when the received primary signal source identification does not match a source identification of the currently selected global positioning system signal, triggering an error.

12. The method of claim 10 , further comprising:

when receiving, at the selector circuit, a rising edge of a pulse per second signal component of the global positioning system signal:

setting a bi-directional pin to an input pin; and

receiving the primary signal source identification; and

when receiving, at the selector circuit, a falling edge of the pulse per second signal component of the global positioning system signal:

setting the bi-directional pin to an output pin; and

outputting the primary signal source identification and the secondary signal source identification.

13. The method of claim 12 , further comprising when receiving the rising edge of the pulse per second signal component of the global positioning system signal:

comparing the received primary signal source identification with the primary signal source identification outputted after the previous falling edge of the pulse per second signal component; and

triggering an error when the primary signal source identifications do not match.

14. A method comprising:

receiving global positioning system signals from global positioning system receivers, the global positioning system receivers receiving the global positioning system signals from corresponding global positioning system satellites;

receiving at a replicator the global positioning system signals from the global positioning system receivers, the replicator replicating the global positioning system signals; and

receiving the global positioning system signals at multiple selectors in communication with the replicator, each selector:

receiving from the replicator the global positioning system signal from each global positioning system receiver;

determining a signal quality score of each received global positioning system signal based on a signal drift and a phase precision of the corresponding global positioning system signal; and

selecting one of the received global positioning system signals having the highest signal quality score.

15. A signal source selector system comprising:

a receiver circuit receiving global positioning system signals from global positioning system receivers, the global positioning system receivers receiving the global positioning system signals from corresponding global positioning system satellites; and

a selector circuit in communication with the receiver circuit, the selector circuit:

determining a signal quality score of each received global positioning system signal based on a signal drift and a phase precision of the corresponding global positioning system signal;

for each signal quality score:

associating a source identification with the signal quality score, the source identification identifying a global positioning system satellite sending the global positioning system signal; and

storing the signal quality score and the associated source identification in non-transitory memory; and

selecting one of the received global positioning system signals having the highest signal quality score and the source identification associated with the received global positioning system signal having the highest signal score.

16. The system of claim 15 , wherein the receiver circuit and selector circuit are on a system-on-chip.

17. A signal source selector system comprising:

a receiver circuit receiving global positioning system signals from global positioning system receivers, the global positioning system receivers receiving the global positioning system signals from corresponding global positioning system satellites; and

a selector circuit in communication with the receiver circuit, the selector circuit:

determining a signal quality score of each received global positioning system signal based on a signal drift and a phase precision of the corresponding global positioning system signal; and

selecting one of the received global positioning system signals having the highest signal quality score,

wherein each global positioning system signal comprises a frequency signal component, a pulse per second signal component, and a time-of-day signal component.

18. The system of claim 17 , wherein the signal drift comprises a drift of the pulse per second signal component and a drift of the frequency signal component.

19. The system of claim 18 , wherein the selector circuit determines the signal quality of a signal by calculating:

J i =g J ( J i F , J i P )

wherein J i is a total drift of a signal, J i F is the frequency drift of a signal, J i P is the pulse per second drift of the signal, and g J is a function of the frequency drift and the pulse per second drift of the signal.

20. The system of claim 17 , wherein the phase precision comprises:

an offline measurement of a propagation delay of the pulse per second component of the corresponding global positioning system signal between the corresponding global positioning system receiver and the selector circuit; and

an online measurement of a relative phase offset of the pulse per second signal component, the relative phase offset determined based on a reference pulse per second reference signal.

21. The system of claim 20 , wherein the reference signal is the received pulse per second signal component received at the selector circuit or a signal generated by a high-precision high-frequency oscillator.

22. The system of claim 21 , wherein the selector circuit determines the phase precision of the global positioning system signal by calculating:

D i =D i P −D i R

wherein D i is the phase precision of a signal, D i P is the offline measurement of the propagation delay of the pulse per second signal component between the corresponding global positioning system receiver and the selector circuit, and D i R is the online measurement of the relative phase offset of the pulse per second signal component.

23. The system of claim 22 , wherein the selector circuit determines the signal quality score by calculating:

S i =g s (Δ D i , J i )

wherein S i is the signal quality score of a received signal, g s is a function for determining the signal quality score, and ΔD i is a convergence of a phase accuracy of the pulse per second signal component determined by calculating:

Δ D i =|D i −D m |

where D m is a median value of {D i }.

24. A signal source selector system comprising:

a receiver circuit configured to receive global positioning system signals from global positioning system receivers, the global positioning system receivers receiving the global positioning system signals from corresponding global positioning system satellites; and

a selector circuit in communication with the receiver circuit, the selector circuit configured to iterate through each of the global positioning system signals from global positioning system receivers, and for each iteration, the selector circuit is configured to request and receive from the receiver circuit a primary signal comprising a currently selected global positioning system signal having a currently highest signal quality score and a secondary signal comprising the global positioning system signal of the corresponding iteration,

wherein after iterating through all of the global positioning system signals from the global positioning system receivers, the selector circuit is further configured to:

determine a signal quality score of each received global positioning system signal based on a signal drift and a phase precision of the corresponding global positioning system signal; and

select the global positioning system signal having the highest signal quality score as the primary signal.

25. The system of claim 24 , wherein the selector circuit requests and receives from the receiver circuit a source identification of the primary signal and a source identification of the secondary signal.

26. The system of claim 25 , wherein when the selector circuit receives a primary signal source identification from the receiver circuit not matching a source identification of the currently selected global positioning system signal, the selector circuit triggers an error in the system.

27. The system of claim 25 , wherein:

the receiver circuit comprises multiple output pins and one bi-directional pin;

the selector circuit comprises an equal number of input pins as output pins of the receiver circuit and one bi-directional pin, the output pins of the receiver circuit in communication with the corresponding input pins of the selector circuit, and the bi-directional pin of the receiver circuit in communication with the bi-directional pin of the selector circuit;

when the receiver circuit receives a rising edge of a pulse per second signal component of the global positioning system signal, the receiver circuit sets its bi-directional pin to an output pin outputting an identification of the primary signal;

when the receiver circuit receives a falling edge of the pulse per second signal component of the global positioning system signal, the receiver circuit:

sets its bi-directional pin to an input pin; and

receives the primary signal source identification and the secondary signal source identification from the selector circuit;

when the selector circuit receives the rising edge of the pulse per second signal component of the global positioning system signal, the selector circuit:

sets its bi-directional pin to an input pin; and

receives the primary signal source identification from the receiver circuit; and

when the selector circuit receives the falling edge of the pulse per second signal component of the global positioning system signal, the selector circuit:

sets its bi-directional pin to an output pin; and

outputting the primary signal source identification and the secondary signal source identification.

28. The system of claim 27 , wherein when the receiver circuit receives the falling edge of the pulse per second signal component of the global positioning system signal, the receiver circuit changes sources of global positioning system signals for the primary and secondary signals to sources corresponding to the received primary signal source identification and the received secondary signal source identification.

29. The system of claim 27 , wherein when the selector circuit receives the rising edge of the pulse per second signal component of the global positioning system signal, the selector circuit:

compares the primary signal source identification received from the receiver circuit with the primary signal source identification outputted to the replicator after the previous falling edge of the pulse per second signal component; and

triggers an error in the system when the primary signal source identifications do not match.

30. A signal source selector system comprising:

a receiver circuit receiving global positioning system signals from global positioning system receivers, the global positioning system receivers receiving the global positioning system signals from corresponding global positioning system satellites;

a replicator receiving and replicating global positioning system signals from global positioning system receivers, the global positioning system receivers receiving the global positioning system signals from corresponding global positioning system satellites; and

multiple selector circuits in communication with the replicator, each selector circuit:

receiving from the replicator the global positioning system signal from each global positioning system receiver;

determining a signal quality score of each received global positioning system signal based on a signal drift and a phase precision of the corresponding global positioning system signal; and

selecting one of the received global positioning system signals having the highest signal quality score.