Hardware module for determining a clock value based on multiple timing references

1. A hardware module, comprising:

a high stability oscillator configured to provide a first timing reference output;

a satellite signal receiver configured to receive signals transmitted by location positioning satellites and provide a second timing reference output;

a processor configured to use the first timing reference output from the high stability oscillator and the second timing reference output from the satellite signal receiver to align the first timing reference output to the second timing reference output by being configured to iteratively determine a difference value associated with the first timing reference output and the second timing reference output, determine an absolute physical hardware clock value, and provide the absolute physical hardware clock value to a host system; and

electrical contacts configured to allow the hardware module to be electrically and physically coupled to and removable from the host system as a single physical module.

2. The hardware module of claim 1 , wherein the high stability oscillator includes an atomic clock.

3. The hardware module of claim 1 , wherein the processor comprises a field-programmable gate array.

4. The hardware module of claim 1 , wherein the host system includes a computer system that includes a network interface.

5. The hardware module of claim 1 , wherein the host system includes a time provider for devices connected through a network.

6. The hardware module of claim 1 , wherein the host system provides time for devices connected through a network using precision time protocol.

7. The hardware module of claim 1 , wherein the processor includes a digital phase-locked loop.

8. The hardware module of claim 1 , wherein the hardware module is configured to connect to the host system through a peripheral component interconnect express interface.

9. The hardware module of claim 1 , wherein the second timing reference output includes a time of day.

10. The hardware module of claim 1 , wherein the processor is further configured to receive programming instructions from the host system.

11. The hardware module of claim 1 , wherein the processor is configured to iteratively determine the difference value including by being configured to determine an offset between a pulse per second signal associated with the second timing reference output and a periodic waveform associated with the first timing reference output.

12. The hardware module of claim 11 , wherein the periodic waveform has been multiplied by the processor.

13. The hardware module of claim 11 , wherein the periodic waveform has been filtered by the processor.

14. A hardware module, comprising:

a high stability oscillator configured to provide a first timing reference output;

a satellite signal receiver configured to receive signals transmitted by location positioning satellites and provide a second timing reference output;

a processor configured to:

determine whether the satellite signal receiver is experiencing an outage event;

use the first timing reference output from the high stability oscillator and the second timing reference output from the satellite signal receiver to determine an absolute physical hardware clock value; and

provide the absolute physical hardware clock value to a host system including by being configured to; and

electrical contacts configured to allow the hardware module to be electrically and physically coupled to and removable from the host system.

15. The hardware module of claim 14 , wherein the processor is configured to, in response to a determination that the satellite signal receiver is experiencing the outage event, determine the absolute physical hardware clock value based on the first timing reference output from the high stability oscillator.

16. The hardware module of claim 14 , wherein the processor is configured to, in response to a determination that the satellite signal receiver is not experiencing the outage event, determine the absolute physical hardware clock value based on the second timing reference output from the satellite signal receiver.

17. A method, comprising:

providing a first timing reference output via a high stability oscillator;

receiving signals transmitted by location positioning satellites and providing a second timing reference output via a satellite signal receiver; and

using the first timing reference output from the high stability oscillator and the second timing reference output from the satellite signal receiver to align the first timing reference output to the second timing reference output by iteratively determining a difference value associated with the first timing reference output and the second timing reference output and determine an absolute physical hardware clock value; and

providing the absolute physical hardware clock value to a host system via a single physical module that is electrically and physically coupled to and removable from the host system through electrical contacts.

18. The method of claim 17 , wherein iteratively determining the difference value includes determining an offset between a pulse per second signal associated with the second timing reference output and a periodic waveform associated with the first timing reference output.

19. The method of claim 18 , further comprising filtering the periodic waveform.

20. The method of claim 18 , further comprising multiplying the periodic waveform.