Analog Storage Array for Lidar Time-of-Flight Signal Management
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Solution Overview
Problem
Conventional lidar systems require a large number of storage elements to accurately measure distances, leading to increased size and cost, as most stored values during the time-of-flight window relate to ambient data, which can be reused and overwritten.
Innovation Solution
Implementing an analog storage array with a control circuit that writes and overwrites output signal values to a subset of storage elements during the time-of-flight window, reserving only those related to detected events for later processing, allowing for a reduction in the number of required storage elements and alleviating the burden on analog-to-digital conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If storage elements are used to store data from sensor elements during the entire time-of-flight window, then measurement precision is maintained, but the number of required storage elements increases significantly
Solution Approach 1:
The patent segments the time-of-flight window into multiple storage intervals, with each storage element handling data for a specific interval. This allows the system to maintain full measurement precision across the entire TOF window while using far fewer storage elements than would be required if each element had to store data for the entire window simultaneously.
Solution Approach 2:
The patent implements periodic writing of sensor data to storage elements in a cyclic manner. Storage elements are written to in sequence across multiple TOF windows, with each element being actively used for only a portion of the total TOF duration. This periodic action enables the system to achieve complete coverage with a reduced set of storage elements.
2Measurement precision
If more storage elements are used to handle larger distances and higher precision, then measurement capability is improved, but device size and cost increase
Solution Approach 1:
The patent makes storage elements universal by having them perform multiple functions across different time periods. Each storage element serves as an active storage location for different TOF windows at different times, rather than being dedicated to a single interval. This multi-functionality allows the same physical storage elements to support extended measurement ranges and high precision requirements without proportionally increasing device complexity.
3Loss of information
If all stored data from storage elements is digitized after the TOF window, then complete data processing is achieved, but the burden on analog-to-digital conversion increases
Solution Approach 1:
The patent segments the data conversion process by having the analog-to-digital converter process data from storage elements in sequence as each element is written, rather than waiting to convert all data after the entire TOF window completes. This segmentation distributes the conversion burden across multiple time points, reducing the peak load on the ADC while ensuring complete data processing.
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 reduces the overall size and cost of the lidar receiver by minimizing the number of storage elements and digital storage needed, while maintaining precise distance measurements by reserving relevant data for further processing.
Implementation Method 1
The at least one photodetector is configured to generate output signals indicative of received optical signals
Data Source
AI summary
A system and method for storing sensed values in an optical receiver corresponding to time-of-flight windows for receiving optical signals elicited by emitted optical pulses includes at least one photodetector, a storage array, and a control circuit. The at least one photodetector is configured to generate output signals indicative of received optical signals. The storage array includes a plurality of storage elements and is connected to receive and store the output signals from the at least one photodetector corresponding to at least a portion of a time-of-flight receive window. The control circuit is configured to control storage of output signal values by the storage array, and is configured to: write and overwrite the output signal values to a first subset of the plurality of storage elements, detect an event based on the written output values, and retain data on respective analog storage elements that comprise at least the first subset of the plurality of storage elements in response to detection of the event.