Lidar Signal Processing System for Optical Carrier Separation
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Solution Overview
Problem
The frequency bands of residual optical carrier and phase-coded optical sideband signals obtained in current modulation processing overlap, leading to insufficient precision and accuracy in Doppler frequency shift and distance/speed measurements.
Innovation Solution
A signal processing system performs first and second modulation processes on subcarrier signals and signal light to generate transmission signal light with non-overlapping frequency bands for single-frequency optical carrier and optical sideband signals, using components like frequency mixers and modulators to separate these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase coding is used to perform modulation processing on an optical carrier to obtain transmission signal, then the transmission signal can be generated with good compression performance, but the frequency bands of residual optical carrier and phase-coded optical sideband signal overlap, causing insufficient measurement precision
Solution Approach 1:
The patent divides the optical signal into separate frequency bands by introducing a frequency shift between the optical carrier and optical sideband signal. The optical carrier and optical sideband signal are segmented into non-overlapping frequency ranges through frequency shifting modulation, allowing independent processing and measurement of each signal component without mutual interference.
Solution Approach 2:
The patent changes the frequency parameter of the optical carrier by introducing a frequency shift Δf. This parameter change separates the optical carrier frequency from the optical sideband signal frequency, transforming the overlapping frequency bands into non-overlapping bands, thereby enabling precise separation and measurement of the signals.
2Ease of manufacture
If phase coding is used to perform modulation processing on an optical carrier, then transmission signal can be generated, but frequency band overlap between residual optical carrier and phase-coded optical sideband signal occurs, resulting in low distance measurement accuracy
Solution Approach 1:
The patent segments the transmission signal into distinct frequency components by applying frequency shifting. The optical carrier and optical sideband signal are separated into different frequency segments, allowing independent distance measurement for each component without cross-interference, thereby improving overall measurement accuracy.
Solution Approach 2:
The patent introduces a frequency shift mechanism as an intermediary element that mediates between the optical carrier and optical sideband signal. This frequency shift acts as a separator, preventing direct frequency overlap and enabling independent processing of each signal component for accurate distance measurement.
3Ease of manufacture
If phase coding is used to perform modulation processing on an optical carrier, then transmission signal can be obtained, but frequency band overlap occurs, leading to low speed measurement accuracy
Solution Approach 1:
The patent applies frequency shifting to change the frequency parameter of the optical carrier, creating a frequency difference between the optical carrier and optical sideband signal. This parameter change separates the frequency bands, enabling independent speed measurement of each signal component through Doppler frequency shift analysis without mutual interference.
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
The solution achieves precise separation of optical carrier and sideband signals, enhancing the accuracy of Doppler frequency shift and distance measurements by eliminating frequency band overlap.
Implementation Method 1
The modulation unit is configured to perform at least first modulation processing on a first subcarrier signal, to obtain a second subcarrier signal. The modulation unit is further configured to perform at least second modulation processing on the second subcarrier signal and first signal light, to obtain transmission signal light.
Implementation Method 2
a Doppler frequency shift signal and a phase-coded signal are obtained based on a signal reflected by the transmission signal through a target and a local oscillator optical signal, to measure a relative movement speed and a relative distance between the target and a radar system based on the Doppler frequency shift signal and the phase-coded signal
Data Source
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AI summary
This application discloses a signal processing system and a terminal device, and relates to the field of lidar technologies. The signal processing system includes a modulation unit and a transmission unit. The modulation unit is configured to perform at least first modulation processing on a first subcarrier signal, to obtain a second subcarrier signal. The modulation unit is further configured to perform at least second modulation processing on the second subcarrier signal and first signal light, to obtain transmission signal light. The transmission signal light includes a single-frequency optical carrier signal and an optical sideband signal, and a frequency band of the single-frequency optical carrier signal and a frequency band of the optical sideband signal do not completely overlap. The transmission unit is configured to transmit the transmission signal light. The signal processing system can resolve a problem of frequency band overlapping between the residual optical carrier and the optical sideband signal that are obtained after modulation processing, to enable a residual optical carrier signal and the optical sideband signal to be separated.