System and method for dual polarization radar with automatic built-in test equipment and calibration

• US 7,592,948 B2
• Filed: 11/16/2007
• Issued: 09/22/2009
• Est. Priority Date: 03/13/2007
• Status: Active Grant

• Current Assignee: Baron Services Incorporated
• Original Assignee: Baron Services Incorporated
• Inventors: Walker, William H.
• Primary Examiner(s): Gregory; Bernarr E
• Application Number:
  US11/941,905
• Publication Number:
  US 20080224919A1
• Time in Patent Office: 676 Days
• Field of Search: 342 5- 11, 342 26 R- 26 D, 342/59, 342165-175, 342/188, 342192-197, 342361-366
• US Class Current: 342/174
• CPC Class Codes: G01S 13/95 for meteorological use
• CPC Class Codes: G01S 7/025 involving the transmission of linearly polarised waves
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: G01S 7/4052 by simulation of echoes
• CPC Class Codes: G01S 7/4065 involving a delay line
• CPC Class Codes: G01S 7/4069 involving a RF signal injection
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

A method of calibrating a dual polarization weather radar system has been developed. The method first generates a transmission pulse from the radar system. The transmission pulse is then modified to generate a test signal that simulates a desired atmospheric condition. The test signal is transmitted directly into the radar system from a test antenna and the radar system is calibrated according to the test signal.

Claims

1. A method of calibrating a dual polarization radar system, comprising:

generating a transmission pulse from the dual polarization radar system;

modifying the transmission pulse by capturing a partial wavelength sample of the transmission pulse that is used to generate a test signal that simulates a desired atmospheric condition;

transmitting the test signal directly into the radar system from a test antenna; and

calibrating the radar system according to the test signal.

2. The method of claim 1, where the transmission pulse has a wavelength of about 300 meters.

3. The method of claim 2, where the captured portion of the transmission pulse is about 30 meters in length.

4. The method of claim 1, where the desired atmospheric condition is simulated by manipulating the phase and amplitude of the test signal.

5. The method of claim 1, where the simulated atmospheric condition is backscattered energy from a meteorological hydrometer.

6. A calibration system for a dual polarization radar system, comprising:

a dual polarization radar transmitter antenna that generates a transmission pulse;

a snipper circuit that captures a sample of the transmission pulse and stores the sample for use in generating a test signal;

a calibration circuit that receives the sample of the transmission pulse and generates a test signal that simulates a desired atmospheric condition; and

a test antenna that transmits the test signal to the dual polarization radar transmitter antenna for calibration of the system.

7. The calibration system of claim 6, where the calibration circuit comprises a variable ratio power divider circuit.

8. The calibration system of claim 6, where the calibration circuit comprises a digital beam forming circuit.

9. The calibration system of claim 8, where the digital beam forming circuit utilizes coaxial circuitry.

10. The calibration system of claim 8, where the digital beam forming circuit uses a low power microwave signal.

11. The calibration system of claim 6, where the transmission pulse has a wavelength of about 300 meters.

12. The calibration system of claim 6, where the sampled portion of the transmission pulse has a wavelength of about 30 meters in length.

13. The calibration system of claim 6, where the calibration circuit further comprises a digital phase shifter that compensates for Doppler shift in the test signal.

14. The calibration system of claim 6, where the calibration circuit further comprises a dual sensor peak power meter that reads transmitted power from the system.

15. The calibration system of claim 6, where the test antenna is centered in the vertex of the radar transmitter antenna so that the test antenna is located within the shadow of an operational feed of the radar transmitter antenna.