Timer Circuit for Optoelectronic Range Finder
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Solution Overview
Problem
Existing time measurement circuits in optoelectronic distance meters face challenges such as limited detection capability for weak backscattered pulses, insufficient resolution in time determination, and increased complexity and calibration effort due to the use of separate threshold value and wave form digitizing methods, leading to inconsistent distance values and high design and computational effort.
Innovation Solution
A time measurement circuit that includes a comparator stage, a signal generation stage to create a form signal of known shape and amplitude, and an evaluation unit for precise time interpolation, allowing for accurate determination of the time position of incoming analog signals, thereby improving detection accuracy and reducing complexity across different signal dynamic ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the threshold value method is used for detecting backscattered pulses, then noise and interference signals are prevented from being incorrectly detected, but weak backscattered pulses with intensity below the detection threshold cannot be detected
Solution Approach 1:
The receiving circuit is divided into two independent channels: a first channel for strong signals using threshold value method, and a second channel for weak signals using wave form digitizing method. This segmentation allows each channel to be optimized for its specific signal strength range, resolving the contradiction between reliable detection and extended detection range.
Solution Approach 2:
The system implements a universal receiving circuit that can handle both strong and weak backscattered pulses through multi-functional channels. The first channel provides reliable detection for strong signals while the second channel extends detection capability to weak signals, making the overall system adaptable to various signal conditions.
2Measurement precision
If the wave form digitizing method is used for detecting backscattered pulses, then weak signals and noisy backgrounds can be managed with high accuracy, but the receiver circuit saturates at close range causing insufficient accuracy
Solution Approach 1:
The receiving circuit is segmented into two channels: the second channel uses wave form digitizing method for weak signals to achieve high time determination accuracy, while the first channel handles strong signals to prevent saturation. This segmentation resolves the contradiction between measurement precision and signal dynamic range adaptability.
Solution Approach 2:
Each channel is designed with local quality optimized for its specific function: the second channel is optimized for weak signal detection with high precision, while the first channel is optimized for strong signal handling. This local optimization allows the system to maintain high accuracy across the entire signal dynamic range.
3Adaptability or versatility
If separate threshold value method and wave form digitizing method are used for different signal dynamic ranges, then both strong and weak signals can be detected, but the structure complexity and calibration effort increase
Solution Approach 1:
The receiving circuit is segmented into two independent channels, each dedicated to a specific signal strength range. This segmentation allows independent optimization of each channel while maintaining overall system simplicity, as each channel can be designed and calibrated separately without affecting the other.
Solution Approach 2:
The system changes the operational parameters of the receiving circuit based on signal strength: for strong signals, the threshold value method is activated; for weak signals, the wave form digitizing method is activated. This parameter change approach allows the system to adapt to different signal conditions while managing complexity through controlled switching between methods.
4Adaptability or versatility
If separate threshold value method and wave form digitizing method are used for different signal dynamic ranges, then both strong and weak signals can be detected, but the computational effort and calibration time increase
Solution Approach 1:
The calibration process is segmented into separate calibration procedures for each channel: the first channel is calibrated for strong signal detection while the second channel is calibrated for weak signal detection. This segmentation allows parallel calibration operations and reduces total calibration time by avoiding the need to recalibrate the entire system when signal conditions change.
Solution Approach 2:
Each channel is pre-calibrated for its specific signal strength range before actual measurement operations. This preliminary calibration ensures that the optimal detection parameters are already set for both strong and weak signals, eliminating the need for time-consuming recalibration during operation and reducing overall calibration time.
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
The solution enables precise time measurement with picosecond accuracy, reduces uncertainty in time and amplitude, and enhances distance measurement accuracy over an extended dynamic range, allowing for consistent high-precision distance measurement regardless of signal strength, even in scenarios with overlapping pulses from double targets.
Implementation Method 1
a (in particular analog) comparator stage for generating a comparator output signal depending on whether a criterion is met by the incoming analog signal, in particular where the criterion is defined as exceeding or falling below a threshold value
Implementation Method 2
a digitizing stage (ADC, analog to-digital converter) for sampling an input signal supplied to the digitizing stage at a defined sampling rate and converting it into sampled values for the digital data containing the input signal
Implementation Method 3
an evaluation unit for determining a time position for the incoming analog signal by evaluating the digital data, in particular using a time interpolation of the values contained in the digital data and the known form of the form signal
Implementation Method 4
a signal generation stage which is designed to generate a form signal of known form and in particular of known amplitude
Implementation Method 5
One approach is to emit pulsed electromagnetic radiation, such as laser light, onto a target to be measured and then to receive an echo from this target as a backscattering object, whereby the distance to the target to be measured can be determined based on the transit time of the pulse
Data Source
Figure 1a~2b
Figure 3a~4
Figure 5~6a
AI summary
The invention relates to a timing circuit for an incoming signal. The timing circuit includes a comparator stage for generating a comparator output signal depending on whether the incoming signal fulfills a criterion, in particular where the criterion is defined as exceeding or falling below a threshold value. Furthermore, a digitizer stage is provided for sampling an input signal supplied to the digitizer stage at a defined sampling rate and converting it into sampled values for digital data containing the input signal, as well as an evaluation unit for determining the temporal position of the incoming signal by evaluating the digital data.According to the invention, a signal generation stage is interposed between the comparator stage and the digitizer stage. This signal generation stage is designed to generate and output a shape signal of known form, designed for post-sampling interpolation, with a timing fixed based on the receipt of the comparator output signal. The evaluation unit then ultimately determines the time for the incoming signal by using a temporal interpolation of the values contained in the digital data and the known form of the shape signal.