Echo Signal Suppression in Distance Measuring Devices
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Solution Overview
Problem
Existing distance measuring devices with the transmitter and receiver in the same optical path suffer from direct optical crosstalk, leading to interference at short measurement distances, limiting the range to around 100 meters due to a 'blind' window that prevents measurement during crosstalk, and existing solutions either disable measurement or require complex signal inversion.
Innovation Solution
The method involves subtracting the signal generated by the receiver from a counter-signal to reduce or eliminate interference, using a microprocessor to analyze and adjust the signal to compensate for crosstalk, allowing measurements at short distances by regulating the signal to achieve a desired level free from reflections and scattered light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the transmitter and receiver are arranged in the same optical path, then the device structure is simplified, but optical crosstalk occurs causing interference at short measurement distances
Solution Approach 1:
The patent applies preliminary anti-action by generating a counter-signal that anticipates and cancels the optical crosstalk before it interferes with the measurement. The system predicts the crosstalk signal characteristics and subtracts a corresponding counter-signal from the received signal, preventing the harmful effect from corrupting the measurement data.
Solution Approach 2:
The patent converts the harmful optical crosstalk into a beneficial signal by measuring its characteristics and using it to generate a counter-signal. The previously harmful crosstalk becomes the basis for creating a cancellation signal that eliminates interference, transforming the problem into a solution.
2Object-affected harmful factors
If a blind window is used to block crosstalk, then optical crosstalk interference is eliminated, but no measurement can be carried out during this window
Solution Approach 1:
The patent implements feedback by continuously monitoring the received signal characteristics, identifying crosstalk components, and dynamically adjusting the counter-signal subtraction in real-time. This feedback loop allows the system to maintain measurement continuity while actively canceling crosstalk, eliminating the need for blind windows.
3Measurement precision
If signal inversion is used to compensate for crosstalk, then measurement at short distances becomes possible, but the system complexity increases
Solution Approach 1:
The patent applies copying by creating a simplified model or representation of the crosstalk signal and using this copy to generate the counter-signal. Instead of complex real-time analysis, the system uses a copied signal model that can be easily subtracted, reducing processing complexity while maintaining effectiveness.
4Object-affected harmful factors
If structural measures like screens are used to reduce crosstalk, then optical crosstalk is minimized, but the device structure becomes more complex
Solution Approach 1:
The patent replaces mechanical/structural crosstalk reduction measures with an electronic signal processing solution. Instead of using physical screens or complex optical isolation mechanisms, the system uses electronic counter-signal subtraction to cancel crosstalk, transitioning from mechanical to electronic domain for simpler implementation.
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 enables accurate distance measurements at short ranges without suppressing useful echoes, and compensates for changing crosstalk conditions over time, such as due to dust or thermal influences, by calibrating the counter-pulse to reduce optical crosstalk effectively.
Implementation Method 1
a laser pulse or pulse trains are emitted by a transmitter, reflected by the target object, detected by a receiver
Implementation Method 2
detected by a receiver, and based on the time delay between the transmitter and Received pulses
Implementation Method 3
a laser pulse or pulse trains are emitted by a transmitter
Implementation Method 4
the transmitter and receiver can be arranged at least partially in the same optical path
Data Source
Figure 1~3
AI summary
The method involves generating a counter signal corresponding to an echo signal and superimposing a signal (I-1) generated by a receiver (2). The signal generated by receiver and the counter signal are superimposed in an additive and subtractive manner. A resultant signal of the signal generated by the receiver and the counter signal is reinforced. A height, an amount, amplitude or a pulse-shaped counter signal is varied in a calibration step. An independent claim is included for a remote optical device with an optical path.