Radar Phase Shifter Calibration via Chirp Signal Comparison
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radar systems employing beamforming or DDMA techniques face challenges due to device-dependent non-linearity in transmission phase-shifters, which can lead to insufficient calibration, especially under temperature or aging effects.
Innovation Solution
A radar system is designed with transmit and receive circuitry that transmits and receives chirp signals with and without induced phase shifts, allowing for the comparison of phases to determine actual phase shifts and calibrate the phase shifters effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If factory calibration is performed during manufacturing, then initial phase accuracy is improved, but calibration accuracy deteriorates under temperature and aging effects
Solution Approach 1:
The patent performs preliminary calibration actions at the factory to establish baseline phase accuracy, then supplements this with field calibration procedures that can be executed periodically or on-demand to maintain accuracy under varying temperature and aging conditions. The system prepares calibration lookup tables and correction factors in advance that can be applied during field operations.
Solution Approach 2:
The patent implements feedback mechanisms where the radar system continuously monitors its own phase performance and compares it against reference values. Based on this feedback, the system automatically adjusts phase shift器 settings or applies corrections from calibration tables to maintain accurate phase measurement despite temperature drift and aging effects.
2Ease of manufacture
If on-chip loopback calibration is used, then phase shift calibration is simplified, but accuracy deteriorates due to onboard routing mismatches
Solution Approach 1:
The patent extracts the calibration signal path from the problematic onboard routing by using separate calibration signal paths that bypass the main signal transmission routes. This allows calibration to be performed independently of the routing mismatches that affect normal signal transmission, thereby maintaining both simplicity and accuracy.
Solution Approach 2:
The patent introduces intermediary calibration signals and reference paths that mediate between the phase shift器 and the measurement system. These intermediaries provide known reference levels that allow accurate calibration without being affected by the variable mismatches in the main signal path.
3Measurement precision
If phase shifters are calibrated frequently to account for temperature and aging, then calibration accuracy is improved, but system complexity increases
Solution Approach 1:
The patent performs comprehensive calibration actions preliminarily at the factory to establish detailed lookup tables and correction factors that cover a wide range of temperature and aging conditions. This preliminary calibration reduces the need for frequent complex field calibrations, as the system can interpolate or select appropriate corrections from the pre-computed tables.
Solution Approach 2:
The patent changes the calibration approach from adjusting physical parameters in real-time to using pre-computed lookup tables indexed by temperature and usage age. This transforms the calibration process from a complex real-time adjustment procedure into a simpler table-lookup and interpolation operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate calibration of phase shifters, accounting for temperature and aging effects, thereby improving the directional signal transmission and reception in radar systems.
Implementation Method 1
Radar systems transmit electromagnetic wave signals that objects in their path then reflect
Implementation Method 2
Beamforming is a signal processing technique used with sensor arrays for directional signal transmission or reception. Spatial selectivity is achieved by using adaptive or fixed receive/transmit beam patterns
Implementation Method 3
Doppler division multiple access ('DDMA') is a signal processing technique also used with sensor arrays for identification of unique transmit array elements in the receive path
Implementation Method 4
Processing circuitry of the radar system is configurable to perform Fourier Transform (FT) operations on the first set of digital signals to generate a first array, and perform FT operations on the second set of digital signals to generate a second array
Data Source
AI summary
An example radar system includes transmit, receive and processing circuitry. In operation, the radar system transmits first and second sets of chirp signals in which each chirp signal of the first set of chirp signals has an induced phase shift, receives reflected signals based on the transmitted first and second sets of chirp signals, and generates respective first and second sets of digital signals. Fourier Transform (FT) operations are performed on the first and second sets of digital signals to generate first and second arrays, respectively. The radar system identifies a first peak in the first array and a second peak in the second array representing an object in a field of view. The first and second peaks are at corresponding positions in the first and second arrays, respectively. The radar system then compares the phases of the first and second peaks to determine an actual phase shift for the induced phase shift.