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US 10,371,798 B2Granted
Array and module calibration with delay line
AssigneeRaytheon Company
InventorsDebra J. Tonks, Stephen M. Sparagna, William Kennedy, David A. Ringheiser, Jack Lee
Life of this patent
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Abstract
An apparatus and method for enhanced calibration of radar at the module level supports dual polarization and array calibration and alignment without the use of external test equipment. Utilizing a delay line, loop back capability at the module level allows existing receiver exciter subsystem to be used for calibration. This approach eliminates the need for manual array calibration using external RF monitor subsystem or external test antennas.
Claims14
A method for calibrating a radar apparatus, comprising:
- performing a first measurement comprising measuring a round trip-electrical length of a sub-array transmit path from a first radar signal input port to a first terminal of a circulator in sub-array driver module of a sub-array of the radar apparatus using time domain reflectometry by injecting a first exciter signal to the first radar signal input port when a first short circuit is configured at the first terminal of the circulator and measuring a first reflected signal at the first radar signal input port, the first terminal located between the first radar input port and the circulator;
- performing a second measurement comprising measuring a round trip electrical length of the sub-array transmit path from the first radar signal input port through the circulator via the first terminal of the circulator using time domain reflectometry by injecting a second exciter signal to the first radar signal input port and measuring a second reflected signal at the first radar signal input port when a second short circuit is configured at a second terminal of the circulator and a third short circuit is configured at a third terminal of the circulator, the second terminal of the circulator located between the circulator and a solid state module (SSM) of the sub-array, the third terminal of the circulator located between the circulator and a receiver circuit of the sub-array;
- performing a third measurement comprising measuring an electrical length of a sub-array receive path of the sub-array from the first radar input port through the circulator to a receiver circuit by injecting a third exciter signal to the first radar signal input port and measuring the third exciter signal at the receiver circuit when a short is configured at the second terminal of the circulator;
- performing a fourth measurement comprising measuring an electrical length in the radar apparatus of a transmit and receive path between the sub-array driver module of the sub-array and the solid state module (SSM) of the sub-array by injecting a fourth exciter signal to the first radar signal input port and to the receiver circuit via a passive calibration loop in the SSM, and measuring the fourth exciter signal at the receiver circuit;
- performing a fifth measurement comprising measuring an electrical length in the radar apparatus of a transmit path between the sub-array driver module of the sub-array and the solid state module (SSM) of the radar by injecting a fifth exciter signal to the first radar signal input port and to the receiver circuit via a transmit element in the SSM, and measuring the fifth exciter signal at the receiver circuit;
- adjusting the transmit path between the sub-array driver module of the sub-array and the solid state module (SSM) of the radar by adjusting a phase control circuit in the transmit element of the SSM based on the electrical length of the transmit and receive path including the calibration loop measured in the fourth measurement;
- performing a sixth measurement comprising measuring an electrical length in the radar apparatus of a receive path between the sub-array driver module of the sub-array and the solid state module (SSM) of the radar by injecting a sixth exciter signal to the first radar signal input port and to the receiver circuit via a receive element in the SSM, and measuring the sixth exciter signal at the receiver circuit;
- and
- adjusting the receive path between the sub-array driver module of the sub-array and the solid state module (SSM) of the radar by adjusting a phase control circuit in the receive element of the SSM based on the electrical length of the transmit and receive path including the calibration loop measured in the fourth measurement.
6 more elements
A method for calibrating a radar apparatus, comprising:
- measuring an electrical length L1 in the radar apparatus of a first transmit path of a sub-array from a first radar input port to a circulator in a sub-array driver module;
- determining an electrical length C1 in the radar apparatus of a second transmit path of the sub-array through the circulator in the sub-array driver module by measuring the electrical length C1 together with the electrical length L1;
- determining an electrical length L2 in the radar apparatus of a receive path of the sub-array from the circulator in the sub-array driver module to receiver circuitry by measuring the electrical length L2 together with the electrical length L1 and the electrical length C1;
- determining an electrical length L3 in the radar apparatus of an array element transmit/receive path between the circulator and an array element module of the sub-array by measuring the electrical length L3 together with the electrical lengths L1, L2 and C1 via a passive calibration loop in the array element module;
- determining a transmit electrical length D_tx in the radar apparatus of an array element transmit path between the circulator and the array element module of the radar by measuring the transmit electrical length D_tx of the array element module together with the electrical lengths L1, L2, C1 and L3;
- and
- determining a receive electrical length D_rx in the radar apparatus of an array element receive path between the circulator and the array element module of the radar by measuring the receive electrical length D_rx of the array element module together with the electrical lengths L1, L2, C1 and L3.
4 more elements
Dependencies are inferred from the claim text.