Coherent Ladar Tone and Chirp Waveforms for Range Velocity
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Solution Overview
Problem
Current LADAR systems face challenges in accurately determining the radial velocity and range of targets due to limitations in time-bandwidth waveforms, leading to inefficiencies in high-resolution imaging and range-resolved Doppler or vibration imaging.
Innovation Solution
The method involves transmitting tone waveforms to detect targets, determining radial velocity, and using linear frequency modulation (FM) chirp signals to accurately determine the range, with multiple chirp waveforms transmitted to reduce range ambiguity and avoid backscatter masking, while employing coherent integration and matched filtering for high-resolution imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single waveform is used for target detection, then the system complexity is reduced, but the measurement precision of range and velocity deteriorates
Solution Approach 1:
The patent combines multiple waveform types (tone waveform for velocity, linear FM chirp signals for range) into a unified detection system. The signal processing apparatus integrates processing of both monotone and chirp waveforms to simultaneously determine target velocity and range with high precision, resolving the contradiction by merging multiple waveform-based measurement approaches into a single coherent system.
Solution Approach 2:
The signal processing apparatus is designed to handle multiple waveform types and perform multiple functions (velocity determination via Doppler shift, range determination via time delay) within a single integrated system. This multi-functional approach allows the system to achieve high measurement precision for both range and velocity without requiring separate dedicated systems for each measurement type.
2Measurement precision
If linear FM chirp signals are used to determine range, then the range measurement precision is improved, but the device complexity increases due to multiple waveform transmissions
Solution Approach 1:
The patent merges the processing of linear FM chirp signals with tone waveform processing in a single signal processing apparatus. By combining range determination from chirp signals with velocity determination from tone waveforms in one integrated system, the patent achieves high range measurement precision while managing system complexity through unified signal processing rather than separate dedicated systems.
3Reliability
If multiple chirp waveforms are transmitted to reduce range ambiguity, then the measurement precision and reliability are improved, but the loss of time increases due to multiple transmissions
Solution Approach 1:
The patent employs preliminary action by using tone waveforms to perform initial target detection and velocity determination before transmitting linear FM chirp signals for precise range measurement. This preliminary velocity information helps in designing appropriate chirp signal parameters (such as bandwidth and duration) that can resolve range ambiguities more efficiently, thereby reducing the total time required for multiple chirp transmissions while maintaining high reliability.
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 enhances the accuracy of target detection and imaging by improving range and velocity determination, enabling high-resolution imaging and reducing ambiguities, thereby improving the overall efficiency of LADAR systems.
Implementation Method 1
determining a radial velocity of the target using the echo of the monotone waveform from the target
Implementation Method 2
transmitting, from the LADAR sensor, linear frequency modulation (FM) chirp signals and determining a range to target using echoes from the linear FM chirp signals
Implementation Method 3
employing coherent integration and matched filtering for high-resolution imaging
Data Source
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AI summary
In one aspect, a method includes transmitting a tone waveform from a laser detection and ranging (LADAR) sensor, detecting a target using an echo of the tone waveform reflected from the target, determining a radial velocity of the target using the echo of the monotone waveform from the target, transmitting, from the LADAR sensor, linear frequency modulation (FM) chirp signals and determining a range to target using echoes from the linear FM chirp signals.