Time Delay Estimation Circuit Using Filter Arrays
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Solution Overview
Problem
Conventional time delay estimation methods in laser scanning systems are unable to accurately measure small time intervals, such as those required for precise distance measurement, due to limitations in resolution and energy efficiency, leading to inaccurate distance calculations.
Innovation Solution
A time delay estimation circuit that utilizes a combination of low and high gain filter arrays and a calibration pulse generator to accurately measure time differences between optical pulses, allowing for improved resolution and energy utilization by splitting signals through multiple filters and sampling at high frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional time delay estimation methods are used, then the system is simple and inexpensive, but the measurement precision is insufficient for accurate distance measurement
Solution Approach 1:
The patent divides the time delay measurement into multiple discrete time bins or intervals. By segmenting the measurement process into distinct time windows, the system can accurately determine which bin contains the signal arrival, achieving high precision without requiring complex continuous measurement circuits.
Solution Approach 2:
The patent uses oversampling techniques where the sampling rate exceeds the minimum required by the Nyquist criterion. This excessive sampling provides redundant measurements that improve time delay estimation precision through statistical processing, allowing accurate measurement without proportionally increasing hardware complexity.
2Measurement precision
If the sampling bandwidth is increased to improve resolution, then the measurement precision improves, but the energy consumption increases
Solution Approach 1:
The patent implements oversampling at a fixed moderate bandwidth, using the redundancy of excessive samples to achieve high resolution through digital signal processing rather than relying on high analog bandwidth. This approach consumes less energy than high-bandwidth sampling while achieving equivalent or better precision.
Solution Approach 2:
The patent replaces analog high-bandwidth filtering and processing with digital signal processing techniques. By moving the resolution enhancement from the analog domain (which would require high energy-consuming components) to the digital domain, the system achieves high precision with lower energy consumption.
3Adaptability or versatility
If a single calibration pulse is used, then the calibration is simple, but the dynamic range of pulse durations that can be measured is limited
Solution Approach 1:
The patent uses multiple calibration pulses with different known time delays or characteristics, dividing the calibration process into multiple discrete calibration points. This segmentation allows the system to accurately characterize its response across a wide dynamic range of pulse durations by building up a comprehensive calibration model from individual measurements.
Solution Approach 2:
The patent designs a calibration system that can handle multiple types of pulses and measurement scenarios using a unified approach. The same calibration infrastructure supports measurements across the entire dynamic range, making the system versatile without requiring separate specialized calibration equipment for different pulse types.
Data Source
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AI summary
A time differential is estimated between a plurality of signals by determining a filter response of a first electrical signal with a first filter array, determining a filter response of a second electrical signal with a second filter array, and determining, based at least on the filter response of the first electrical signal and the filter response of the second electrical signal, a time differential between the first electrical signal and the second electrical signal. A first optical signal is converted into the first electrical signal and a second optical signal is converted into the second electrical signal. The filter response of the first electrical signal and the filter response of the second electrical signal are sampled and the time differential between the first electrical signal and the second electrical signal is determined based at least on the sampled filter response of the first electrical signal and the sampled filter response of the second electrical signal.