Phase-modulating communication device

• US 8,204,384 B2
• Filed: 11/20/2009
• Issued: 06/19/2012
• Est. Priority Date: 11/21/2008
• Status: Active Grant

• Current Assignee: Cubic Corporation
• Original Assignee: Cubic Corporation
• Inventors: Amadeo, Paul, Ripingill, Allen, Robinson, David, Chen, Irene
• Primary Examiner(s): Bello, Agustin
• Application Number:
  US12/623,356
• Publication Number:
  US 20100135670A1
• Time in Patent Office: 942 Days
• Field of Search: 398168-170
• US Class Current: 398/170
• CPC Class Codes: H04B 10/1123 Bidirectional transmission
• CPC Class Codes: H04B 10/2587 using a single light source for multiple stations

Abstract

A system, method, and communication device are disclosed. The system can include an optical interrogator and a phase-modulating communication device. The communication device can include a retro-optimized lens, a phase modulator, and a processor. The retro-optimized lens can be a non-imaging optical arrangement configured to minimize deviation between an incoming signal and a reflected signal used for return link communications. The processor can be configured to calibrate a modulation path length of the communication device based on a wavelength of the communication signal and can control an operation of the phase-modulator to send phase-coded messages to the interrogator. Optionally, the processor can perform a real-time phase calibration of the communication device using feedback from the interrogator.

Claims

1. A phase-modulating communication device, comprising:

a housing;

a lens arrangement configured to pass a communication signal into the housing;

a beam splitter optically coupled to the lens arrangement and configured to direct a first part of the communication signal along a reference path and a second part of the communication signal along a modulation path;

a phase modulator configured to vary a length of the modulation path in relation to a length of the reference path responsive to a control signal;

a photodetector configured to detect the communication signal and to output a receive data signal;

a processor coupled to the phase modulator and the photodetector and configured to modulate the control signal based on the receive data signal;

a first reflective element configured to reflect the first part of the communication signal along the reference path and toward a source of the communication signal; and

a second reflective element configured to reflect the second part of the communication signal along the modulation path and toward the source of the communication signal.

2. The communication device of claim 1, wherein the processor is configured to detect a calibration instruction in the receive data signal and to vary the length of the modulation path according to the calibration instruction.

3. The communication device of claim 2, wherein the processor is configured to vary a modulation distance of the phase modulator in response to the calibration instruction.

4. The communication device of claim 1, wherein the lens arrangement comprises a retro-optimized lens.

5. The communication device of claim 4, wherein the retro-optimized lens is configured to minimize a deviation of at least one of the first part or the second part of the communication signal from a respective incident path.

6. The communication device of claim 4, wherein a field of view of the retro-optimized lens is at least ±

50 degrees relative to an optical axis of the retro-optimized lens.

7. The communication device of claim 4, wherein the retro-optimized lens comprises an optical medium having an index of refraction of at least three.

8. The communication device of claim 1, wherein the processor is configured to retrieve calibration data from a memory of the communication device and to establish a base length of the modulation path according to the calibration data.

9. The communication device of claim 1, wherein the phase modulator varies the modulation path length by the modulation distance in response to a transmit data signal from the processor.

10. A method of phase-modulated communication using a device with a reference path and a modulation path, the method comprising:

retrieving calibration data from a memory of the device;

applying a bias signal to one or more actuators of the device according to the calibration data;

adjusting a length of the modulation path in response to the bias signal;

detecting the communication signal at the device;

splitting a first part of the communication signal along the reference path and a second part of the communication signal along the modulation path;

varying the length of the modulation path, based on the detected communication signal, using the one or more actuators to create a phase difference between the second part of the communication signal and the first part of the communication signal; and

reflecting the first part of the communication signal and the second part of the communication signal back along their respective reference path and modulation path away from the device.

11. The method of claim 10, further comprising minimizing a deviation of the first part and the second part of the communication signal from an incident path of the communication signal such that the deviation does not exceed a predetermined value over a field of view of the device.

12. The method of claim 10, wherein the calibration data comprises a path length adjustment determined according to a wavelength of the communication signal.

13. The method of claim 12, wherein the path length adjustment is determined such that the modulation path length is approximately an integral number of wavelengths of the communication signal relative to a length of the reference path.

14. The method of claim 10, further comprising detecting a calibration instruction in the received communication signal and varying the length of the modulation path or a modulation distance of the device in response to the calibration instruction.

15. The method of claim 10, further comprising identifying a sender of the communication signal;

and varying the length of the modulation path based on the identity of the sender.

16. A communication device, comprising:

a housing having an aperture for receiving a communication signal;

an optical arrangement disposed within the housing comprising;

a beam splitter configured to divide the incoming communication signal into a first signal and a second signal;

at least two reflectors, wherein;

a first reflector is configured to reflect the first signal toward a source of the communication signal, and

a second reflector is configured to reflect the second signal toward the source of the communication signal;

a retro-optimized lens optically coupled with the at least two reflectors, the retro-optimized lens configured to minimize a deviation of the reflected first and second signals from an incident path of the communication signal;

a photodetector optically coupled to the communication signal and configured to provide an output; and

a phase modulator coupled to the optical arrangement and configured to selectively vary a phase of one of the first or second reflected signals.

17. The communication device of claim 16, further comprising a processor coupled to the phase modulator and wherein the phase modulator varies the phase of the reflected signal in response to a data signal from the processor.

18. The communication device of claim 17, wherein the processor generates the data signal in response to the output of the photodetector.

19. The communication device of claim 17, wherein the phase modulator varies a path length of the second signal in response to the data signal.

20. The communication device of claim 19, further comprising a memory configured to store calibration data relating to the first and second path lengths, and wherein the processor varies the path length of the second signal based on the calibration data.

21. The communication device of claim 20, wherein the calibration data comprises path length information associated with a plurality of transmitter locations.

22. The communication device of claim 20, wherein the phase modulator comprises one or more electro-mechanical actuators.

23. The communication device of claim 22, wherein the calibration data includes a path length adjustment such that the second path comprises an integral number of wavelengths of the communication signal when the path length adjustment is applied.

24. The communication device of claim 23, wherein the calibration data comprises a bias voltage value, and wherein the processor is configured to control delivery of a bias voltage to the one or more actuators in accordance with the bias voltage value.

25. The communication device of claim 16, wherein the phase modulator comprises an actuator coupled to one or more of the at least two reflectors and wherein the actuator changes from a first state to a second state in response to the data signal.

26. The communication device of claim 25, wherein the actuator comprises a plurality of piezo-electric actuators.

27. The communication device of claim 17, wherein the phase modulator comprises an optical element having a variable index of refraction.

28. The communication device of claim 27, wherein the processor is configured to vary the index of refraction of the optical element.

29. The communication device of claim 18, wherein the processor is configured to detect a sender of the communication signal based on the output of the photodetector and to generate the data signal according to an identity of the sender.

30. The communication device of claim 18, wherein the processor detects a calibration instruction based on the output of the photodetector and varies a path length of the second path or a modulation distance of the phase modulator in response to the calibration instruction.

31. The communication device of claim 16, wherein a field of view of the retro-optimized lens is at least ±

50 degrees relative to an optical axis of the retro-optimized lens.

32. The communication device of claim 16, wherein the retro-optimized lens comprises an optical medium having an index of refraction of at least three.

33. The communication device of claim 16, wherein the phase modulator performs an analog or digital phase modulation of the reflected signal.

34. A phase-modulating retro-reflector, comprising:

a housing having first and second apertures;

a first lens optically coupled to the first aperture for receiving a first portion of an incoming communication signal;

a first reflector optically coupled to the first lens and configured to reflect the first portion of the incoming communication signal along a reference path and toward a source of the communication signal;

a second lens optically coupled to the second aperture for receiving a second portion of the incoming communication signal;

a second reflector optically coupled to the second lens and configured to reflect the second portion of the incoming communication signal along a modulation path toward the source of the communication signal;

an actuator configured to change a state of the second reflector so as to vary a length of the modulation path;

a detector configured to detect the incoming communication signal and provide an output; and

a processor coupled to the actuator for controlling a length of the modulation path in response to the output of the detector.