LIDAR Pulse Amplitude Encoding Without High-Speed ADCs
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Solution Overview
Problem
Existing LIDAR systems require complex and power-intensive circuits for processing high-speed signals, including the need for high-speed analog-to-digital converters (ADCs) and stable clock sources, which complicates the acquisition of amplitude information from reflected laser signals.
Innovation Solution
A LIDAR system and signal processing method utilizing a comparator circuit and encoding algorithm to convert continuous signal pulses into discrete signals using variable reference voltages, eliminating the need for ADCs and separate clock sources, thereby simplifying the circuitry and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-speed ADC is used to acquire amplitude information of the laser signal, then measurement precision is improved, but device complexity increases due to the requirement of a complex circuit for processing high-speed signals
Solution Approach 1:
The patent replaces the high-speed ADC (analog-to-digital converter) with a comparator circuit that uses pulse width modulation and time-to-digital conversion. Instead of directly converting the amplitude of the reflected laser signal using a complex high-speed ADC, the system uses a comparator to generate a pulse whose width is proportional to the signal amplitude, then converts this time information into digital form using a simple counter. This substitution of the conversion mechanism eliminates the need for complex high-speed ADC circuitry while preserving measurement capability.
Solution Approach 2:
The patent transforms the measurement parameter from direct amplitude detection to time-based measurement. By converting the amplitude information into a time-domain representation (pulse width) and then into a digital count value, the system changes the parameter being measured from voltage amplitude to time duration. This parameter transformation allows the use of simple timing circuits instead of complex high-speed analog-to-digital conversion circuitry.
2Measurement precision
If a high-speed ADC is used to process the laser signal, then measurement precision is improved, but use of energy increases due to the power-intensive nature of high-speed signal processing circuits
Solution Approach 1:
The patent replaces the power-intensive high-speed ADC with a low-power comparator and counter-based time-to-digital converter. The comparator circuit consumes minimal power while generating a time-proportional pulse from the amplitude signal. The subsequent digital counting process uses standard low-power digital logic, eliminating the need for continuous high-power analog signal processing. This system substitution dramatically reduces power consumption while maintaining the ability to extract amplitude information.
Solution Approach 2:
By transforming the measurement from direct amplitude sampling (which requires continuous high-power analog processing) to time-based measurement followed by digital counting, the patent changes the energy consumption profile. The time-to-digital conversion process uses discrete, low-power digital operations instead of continuous high-power analog processing, resulting in significantly reduced energy consumption for the same measurement precision.
3Measurement precision
If a clock-based circuit is used to process the laser signal, then measurement precision is improved, but device complexity increases due to the requirement of a high-speed and high-stability clock source and a PLL circuit
Solution Approach 1:
The patent extracts and eliminates the need for a phase-locked loop (PLL) circuit and high-speed clock source from the signal processing chain. By using a comparator to generate a pulse width proportional to the signal amplitude and then using a simple counter to measure this pulse width, the system removes the complex clock synchronization and phase-locking mechanisms. The timing measurement is performed using a straightforward counter that increments during the pulse duration, eliminating the need for sophisticated clock management circuits.
4Measurement precision
If traditional ADC-based systems are used to measure high-speed pulse information, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent substitutes the traditional high-speed ADC system with a comparator-based pulse width modulation system followed by a time-to-digital converter. Instead of using a complex high-speed ADC to directly digitize the reflected laser signal, the system uses a comparator to convert the amplitude information into a time-domain pulse, then uses a simple counter to convert this time information into a digital value. This substitution replaces complex high-speed analog-to-digital conversion with simpler time-based measurement and digital counting, reducing circuit complexity while maintaining measurement precision for high-speed pulse information.
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
Enables the acquisition of amplitude information from reflected pulses using a low-cost and low-power circuit, facilitating efficient high-speed pulse information measurement without the complexity of traditional ADC-based systems.
Implementation Method 1
The LIDAR system in the related art is a measurement sensor of a time of flight (ToF) acquisition scheme, which measures a distance by using a delay time between a laser signal emitted from a laser diode (LD) and a laser signal which is reflected on a target object and returned to a photo diode (PD).
Implementation Method 2
Variable reference voltages having different voltage values may be applied to the m comparators, respectively and each of the m comparators may convert the plurality of input pulses of a continuous signal form into discrete signal forms by using the variable reference voltages.
Data Source
AI summary
A light detection and ranging (LIDAR) system includes a transmitter configured to output a number of output pulses to a target object; a receiver configured to receive a plurality of input pulses corresponding to the number of output pulses; and a signal processor including a signal converter configured to convert the plurality of input pulses into discrete signals and an encoder configured to encode amplitude information of the plurality of input pulses converted into the discrete signals.