Dual APD Waveform Shaping for Narrowband Distance Measurement
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Solution Overview
Problem
Current distance measurement technologies using avalanche photo diodes (APDs) require expensive high-frequency circuits to process signals with wide frequency bandwidths, including harmonic components, which is inefficient and costly.
Innovation Solution
An electronic apparatus comprising a first and second avalanche photo diode, pulse circuits, waveform shaping circuits, and an adder that shapes signals to narrower frequency bandwidths, allowing for accurate distance measurements without the need for expensive high-frequency circuits by modifying the pulse shapes and adding them to reduce the required frequency bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal processing is performed to make photon counting easier, then photon detection sensitivity is improved, but harmonic components are introduced into the processed signals
Solution Approach 1:
The patent extracts and removes the harmful harmonic components from the processed signals by using a bandpass filter that allows only the fundamental frequency to pass through, thereby eliminating the distortion caused by signal processing while preserving the useful photon detection information
Solution Approach 2:
The patent introduces a bandpass filter as an intermediary component between the signal processing stage and the measurement output, which mediates the signal by selectively passing the fundamental frequency and blocking the harmonic components, thus resolving the contradiction between sensitivity improvement and harmonic generation
2Measurement precision
If high frequency circuits are used to process signals with wide frequency bandwidths, then measurement accuracy is improved, but system cost and complexity increase
Solution Approach 1:
The patent replaces expensive, complex high-frequency circuits with simpler, lower-cost wave shaping circuits that generate waveforms with concentrated spectral components, achieving the same measurement accuracy without requiring high-frequency processing capabilities
Solution Approach 2:
The patent changes the waveform parameters by using wave shaping circuits to generate specific waveform shapes (such as triangular or trapezoidal waves) that have narrower spectral bandwidths, thereby allowing accurate distance measurements to be performed with simpler circuits operating at lower frequencies
3Productivity
If APDs with shorter dead times are used, then measurement speed is improved, but the required frequency bandwidth increases
Solution Approach 1:
The patent applies wave shaping processing in advance to the signals from APDs with short dead times, pre-concentrating their spectral components into narrower bandwidths before they reach the measurement system, thereby allowing high-speed measurements without requiring high-frequency bandwidth processing capabilities
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 accurate distance measurements using APDs with shorter dead times without the necessity of expensive high-frequency circuits, reducing costs and improving signal processing efficiency.
Implementation Method 1
avalanche photo diodes (APDs) operating in Geiger mode
Data Source
AI summary
According to one embodiment, an electronic apparatus includes a first avalanche photo diode, a second avalanche photo diode, a first pulse circuit, a second pulse circuit, a first waveform shaping circuit, a second waveform shaping circuit and an adder. The first pulse circuit is configured to shape a signal of the first avalanche photo diode to a first pulse. The second pulse circuit is configured to shape a signal of the second avalanche photo diode to a second pulse. The first waveform shaping circuit is configured to shape the first pulse to a third pulse having a narrower frequency bandwidth than that of the first pulse. The second waveform shaping circuit is configured to shape the second pulse to a fourth pulse having a narrower frequency bandwidth than that of the second pulse. The adder is configured to add the third pulse and the fourth pulse.