Radar Angular Position Estimation via Doppler Frequency
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Solution Overview
Problem
Existing radar systems face limitations in accurately determining the angular position of targets due to low signal-to-noise ratios and limited detection resolution, particularly in single-channel systems, and require additional channels for improved precision, increasing equipment costs.
Innovation Solution
A method using a single reception channel to estimate the angular position of a target by solving an equation relating Doppler frequency and antenna position, minimizing mean square error to improve precision and reduce fluctuations, while also determining radial speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-channel radar performs amplitude analysis during antenna scanning, then the equipment cost is reduced, but the precision of angular position estimation deteriorates due to low signal-to-noise ratio and noise-generated spurious peaks
Solution Approach 1:
The patent transforms the estimation approach from direct amplitude-based angular position measurement to a two-step process: first measuring Doppler frequency (a different physical parameter), then calculating angular position from the Doppler frequency measurement. This parameter transformation allows achieving high precision angular estimation without requiring multiple reception channels, thus resolving the contradiction between equipment simplicity and measurement precision
Solution Approach 2:
The patent replaces the traditional mechanical/amplitude-based angular detection mechanism with a Doppler frequency-based measurement mechanism. Instead of relying on amplitude variations during antenna scanning, the system uses Doppler frequency shifts of the echo signal to infer angular position, thereby achieving high precision with a single reception channel
2Reliability
If Doppler mode analysis is performed in the frequency domain, then detection capability is improved, but the azimuthal detection resolution is limited by the angular resolution separating average azimuths of blocks
Solution Approach 1:
The patent replaces the block-based average azimuth measurement mechanism with a continuous Doppler frequency measurement mechanism. Instead of discretizing the measurement into blocks with average azimuths, the system continuously measures Doppler frequency and directly computes angular position, thereby achieving higher azimuthal resolution without being constrained by block size or overlap requirements
Solution Approach 2:
The patent introduces a new measurement dimension by using Doppler frequency as an intermediate parameter. Rather than directly measuring angular position or average azimuth, the system measures Doppler frequency (a temporal/frequency dimension) and transforms it into angular position information, thereby bypassing the resolution limitations of traditional azimuthal block analysis
3Measurement precision
If azimuthal overlap between consecutive blocks is increased to improve angular resolution, then the precision of target angular position estimation is improved, but the calculation complexity and implementation cost are increased
Solution Approach 1:
The patent replaces the complex block overlap processing mechanism with a simpler Doppler frequency measurement and calculation mechanism. Instead of performing complex correlation operations on overlapping blocks, the system directly measures Doppler frequency and computes angular position through straightforward mathematical relationships, thereby achieving high precision without increased calculation complexity
Solution Approach 2:
The patent extracts the essential measurement information (Doppler frequency) from the echo signal, separating it from the complex block processing requirements. By focusing on Doppler frequency measurement alone, the system eliminates the need for complex block overlap operations while retaining high angular position estimation precision
4Measurement precision
If two reception channels (sum and delta channels) are used to calculate angular position deviation, then angular location precision is considerably increased, but the equipment cost increases due to requiring additional reception channels
Solution Approach 1:
The patent replaces the dual-channel reception system with a single-channel system that measures Doppler frequency. Instead of using two separate reception channels (sum and delta) to compute angular deviation, the system uses one channel to measure Doppler frequency and calculate angular position, thereby achieving comparable or superior precision with reduced equipment cost
Solution Approach 2:
The patent changes the measurement parameter from direct angular deviation (requiring dual channels) to Doppler frequency (measurable with single channel). This parameter transformation enables the system to achieve high angular location precision using only one reception channel, eliminating the need for expensive dual-channel equipment
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 method enhances angular position precision and reduces fluctuations in target azimuth estimation, achieving improved detection performance without the need for multiple reception channels, thereby reducing costs and increasing accuracy.
Implementation Method 1
The general principle of a surveillance radar consists of emitting a series of pulses through a pivoting antenna which scans the angular space to detect the presence of a potential target. If a target is actually present in the antenna beam, the signal pulses are reflected on this target and send echoes back to the radar
Implementation Method 2
a step of estimating, for each pulse or group of pulses of temporal index i, of the Doppler frequency fD(i) of the echo(es) received
Data Source
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AI summary
The method involves estimating an angular position of a steerable antenna (301) for each pulse or group of pulses of time index. Doppler frequency of echoes received from reflection of a radar signal on a target (301) is estimated for each pulse or group of pulses of time index. The angular position and the Doppler frequency are paired. An angular position of the target is estimated by solving a specific equation having parameters of wavelength (Va) of a radar, norm of the speed of a mobile carrier i.e. aircraft (300), and radial speed of the target. An independent claim is also included for a surveillance radar comprising a steerable antenna and an emission unit for emitting a radar signal in the form of pulses.