Method and System for Calibrating ESA, Distributed Waveform Generator and Receivers in Sub-Arrays

• US 20080036648A1
• Filed: 08/10/2006
• Published: 02/14/2008
• Est. Priority Date: 08/10/2006
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Inventors: Green, Patrick Anthony, Dixon, William Blackmore
• Granted Patent: US 7,468,690 B2
• Time in Patent Office: Days
• US Class Current: 342/174
• CPC Class Codes: G01S 7/4008 of transmitters
• CPC Class Codes: G01S 7/4017 of HF systems
• CPC Class Codes: G01S 7/4021 of receivers
• CPC Class Codes: G01S 7/4065 involving a delay line
• CPC Class Codes: G01S 7/4078 involving an integrated reference reflector or reference transponder
• CPC Class Codes: H01Q 21/06 Arrays of individually energised antenna units similarly polarised and spaced apart

Abstract

A system for calibrating waveform generators and receivers of non-overlapping electronic scanning antennas includes a first sub-array, a second sub-array and a calibration cable. The first sub-array includes a first waveform generator, a first receiver, and a first switch assembly. The second sub-array includes a second waveform generator, a second receiver, and a second switch assembly. The calibration cable is configured to selectably form a common calibration path between the first and second sub-arrays based on a position of the first and second switch assemblies. The first and second switch assemblies are configured to enable calibration of the second receiver using an input from the first waveform generator via the calibration cable.

Claims

1. A method for calibrating waveform generators and receivers of non-overlapping electronic scanning antennas, the method comprising:

calibrating a waveform generator and receiver of a first sub-array;

configuring switch assemblies in each of the first sub-array and a second sub-array to provide a connection path between the first and second sub-arrays via a common calibration path;

characterizing the common calibration path;

calibrating a receiver of the second sub-array using the common calibration path; and

calibrating the waveform generator of the second sub-array using the calibrated receiver of the second sub-array.

2. The method of claim 1, wherein configuring switch assemblies comprises switching a switch assembly of the first sub-array to split a calibration signal between the first and second sub-arrays.

3. The method of claim 2, wherein characterizing the common calibration path comprises:

measuring characteristics of the common calibration path while terminating the split calibration signal in a load by placing a switch assembly of the second sub-assembly in a first position;

measuring characteristics of the common calibration path in response to switching of the switch assembly of the second sub-assembly to a second position in order to reflect the split calibration signal back to the first sub-assembly; and

determining the characterization of the common calibration path based on the characteristics measured in the first and second positions.

4. The method of claim 2, wherein calibrating the receiver of the second sub-array comprises utilizing the split calibration signal to match an output of the receiver of the first sub-array with an output of the receiver of the second sub-array by adjusting the receiver of the second sub-array.

5. The method of claim 4, wherein calibrating the waveform generator of the second sub-array comprises:

adjusting the switch assemblies of the first and second sub-arrays to open the connection path between the first and second sub-arrays; and

adjusting the waveform generator of the second sub-array to match the output of the receiver of the first sub-array with the output of the receiver of the second sub-array.

6. The method of claim 1, wherein calibrating the waveform generator and the receiver of the first sub-array comprises:

performing a timing adjustment of a waveform generator local oscillator signal of the first sub-assembly; and

balancing and equalizing the receiver of the first sub-assembly.

8. The method of claim 1, further comprising an initial operation of providing a wrap back path in each of the sub-assemblies which wraps a calibration signal from a transmit manifold of each of the first and second sub-arrays to a receive manifold of each corresponding one of the first and second sub-arrays via at least a portion of a transmit/receive module of each corresponding one of the first and second sub-arrays.

7. The method of claim 7, wherein balancing and equalizing the receiver comprises:

aligning the receiver over both signal and noise levels;

balancing the frequency response of the receiver by minimizing absolute amplitude and phase errors; and

performing a phase shift adjustment for maximum signal strength prior to equalizing.

9. A method for calibrating waveform generators and receivers of non-overlapping electronic scanning antennas, the method comprising:

configuring a first switch assembly in a first sub-array and a second switch assembly in a second sub-array to provide a connection path between the first and second sub-arrays via a common calibration path that has been previously characterized;

calibrating a receiver of the second sub-array using the common calibration path; and

calibrating the waveform generator of the second sub-array using the calibrated receiver of the second sub-array.

10. The method of claim 9, wherein configuring the first switch assembly comprises switching the first switch assembly to split a calibration signal between the first and second sub-arrays.

11. The method of claim 10, wherein calibrating the receiver of the second sub-array comprises utilizing the split calibration signal to match an output of the receiver of the first sub-array with an output of the receiver of the second sub-array by adjusting the receiver of the second sub-array.

12. The method of claim 11, wherein calibrating the waveform generator of the second sub-array comprises:

adjusting the first and second switch assemblies to open the connection path between the first and second sub-arrays; and

adjusting the waveform generator of the second sub-array to match the output of the receiver of the first sub-array with the output of the receiver of the second sub-array.

13. The method of claim 9, further comprising an initial operation of providing a wrap back path in each of the sub-assemblies which wraps a calibration signal from a transmit manifold of each of the first and second sub-arrays to a receive manifold of each corresponding one of the first and second sub-arrays via at least a portion of a transmit/receive module of each corresponding one of the first and second sub-arrays.

14. A system for calibrating waveform generators and receivers of non-overlapping electronic scanning antennas, the system comprising:

a first sub-array including a first waveform generator, a first receiver, and a first switch assembly;

a second sub-array including a second waveform generator, a second receiver, and a second switch assembly; and

a calibration cable configured to selectably form a common calibration path between the first and second sub-arrays based on a position of the first and second switch assemblies, wherein the first and second switch assemblies are configured to enable calibration of the second receiver using an input from the first waveform generator via the calibration cable.

15. The system of claim 14, wherein the first switch assembly is configured to split a calibration signal generated by the first waveform generator between the first and second sub-arrays.

16. The system of claim 15, wherein the second switch assembly is selectable to switch between termination of a portion of the split calibration signal in a load and reflection of the portion of the split calibration signal back to the first sub-array to enable characterization of the common calibration path.

17. The system of claim 14, wherein the first sub-array further comprises a first transmit/receive module having a first wrap back path configured to wrap a calibration signal from a transmit manifold of the first sub-array to a receive manifold of the first sub-array and the second sub-array further comprises a second transmit/receive module having a second wrap back path configured to wrap a signal from a transmit manifold of the second sub-array to a receive manifold of the second sub-array.

18. The system of claim 17, wherein the first wrap back path includes an element for adjusting a phase shift of the calibration signal to enable balancing and equalizing the first receiver.

19. The system of claim 15, wherein the first and second switch assemblies are configured to enable calibrating the receiver of the second sub-array by utilizing the split calibration signal to match an output of the first receiver with an output of the second receiver by adjusting the second receiver.

20. The system of claim 19, wherein the first and second switch assemblies are configured to enable calibrating the second waveform generator by:

adjusting the first and second switch assemblies to open the common calibration path between the first and second sub-arrays; and

adjusting the second waveform generator to match the output of the second receiver with the output of the first receiver.

21. A method for calibrating waveform generators and receivers of overlapping electronic scanning antennas, the method comprising:

calibrating a waveform generator and receiver of a first sub-array and shared sub-array;

calibrating a receiver of the second sub-array using a shared calibration path; and

calibrating the waveform generator of the second sub-array using the calibrated receiver of the second sub-array.

22. The method of claim 21, wherein calibrating the waveform generator of the second sub-array comprises:

adjusting the waveform generator of the second sub-array to match the output of the receiver of the first sub-array with the output of the receiver of the second sub-array.

23. The method of claim 21, wherein calibrating the waveform generator and the receiver of the first sub-array comprises:

performing a timing adjustment of a waveform generator local oscillator signal of the first sub-array; and

balancing and equalizing the receiver of the first sub-array.

24. The method of claim 23, wherein balancing and equalizing the receiver comprises:

aligning the receiver over both signal and noise levels;

balancing the frequency response of the receiver by minimizing absolute amplitude and phase errors; and

performing a phase shift adjustment for maximum signal strength prior to equalizing.

25. The method of claim 21, further comprising an initial operation of providing a wrap back path in each of the sub-assemblies which wraps a calibration signal from a transmit manifold of each of the first and second sub-arrays to a receive manifold of each corresponding one of the first and second sub-arrays via at least a portion of a transmit/receive module of each corresponding one of the first and second sub-arrays.

26. A system for calibrating waveform generators and receivers of overlapping electronic scanning antennas, the system comprising:

a first sub-array including a first waveform generator, a first receiver, and a shared receiver;

a second sub-array including a second waveform generator, a second receiver, and the shared receiver;

27. The system of claim 26, wherein one of the waveform generators is shared as a calibration signal is generated between the first and second receivers.

28. The system of claim 27, wherein the first sub-array further comprises a first transmit/receive module having a first wrap back path configured to wrap a calibration signal from a transmit manifold of the first sub-array to a receive manifold of the first sub-array and shared sub-array and the second sub-array further comprises a second transmit/receive module having a second wrap back path configured to wrap a signal from a transmit manifold of the second sub-array to a receive manifold of the second sub-array and the shared sub-array of the first sub-array.

29. The system of claim 28, wherein the first wrap back path includes an element for adjusting a phase shift of the calibration signal to enable balancing and equalizing the first receiver.