Optical Sensor Digital Signal Processing for Range and Size
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Solution Overview
Problem
Optical sensors for detecting objects in surveillance areas face limitations in range and size due to large optics and limited signal-to-noise ratios, making it difficult to achieve high functionality in a compact design.
Innovation Solution
The optical sensor employs an evaluation unit with an analog-to-digital converter, digital filter, and multiplier to transform high-frequency received signals into low-frequency output signals, improving signal-to-noise ratio and detection reliability, allowing for smaller optics and increased range while using digital components like FPGA or ASIC logic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large optics are used to increase detection range, then detection range is improved, but sensor size increases
Solution Approach 1:
The patent transforms the received signal parameters from high-frequency to low-frequency domain through digital signal processing (mixing with local oscillator and low-pass filtering). This parameter transformation allows the system to achieve better signal-to-noise ratio and extended detection range without requiring larger optical components, as the processing occurs in the digital domain rather than through physical optics scaling.
2Reliability
If large optics are used to improve signal-to-noise ratio, then detection reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces mechanical/optical signal processing approaches with digital electronic processing. Instead of using complex optical systems to enhance signal-to-noise ratio, the invention uses digital mixing with a local oscillator and digital low-pass filtering to achieve the same goal. This substitution of digital processing for mechanical/optical processing simplifies manufacturing while maintaining or improving detection reliability.
3Speed
If high-frequency received signals are processed directly, then detection speed is maintained, but signal-to-noise ratio is limited
Solution Approach 1:
The patent performs preliminary signal processing by mixing the received high-frequency signal with a local oscillator signal before final detection. This preliminary mixing action transforms the signal to a lower frequency where noise is reduced, and subsequent low-pass filtering further improves the signal-to-noise ratio. The detection speed is maintained because the processing is performed in the digital domain with controlled timing, while the preliminary transformation enables better noise performance.
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 enhances detection reliability and range with smaller optics, simplifies manufacturing, and provides precise distance measurements, making the optical sensor more efficient and compact.
Implementation Method 1
The at least one transmitter emits amplitude-modulated light beams in the form of sequences of light pulses
Implementation Method 2
a light-receiving receiver is located at the opposite edge of the monitoring area
Data Source
Figure 1~4
Figure 5~6
Figure 7~8
AI summary
The invention relates to an optical sensor (1) for detecting objects in a monitoring area, comprising a transmitter (4) emitting light beams (3) and a receiver (5) receiving light beams (3), and an evaluation unit (7). In the evaluation unit, an object detection signal is generated based on the received signals from the receiver (5). The light beams (3) are amplitude modulated. The evaluation unit (7) includes an analog-to-digital converter (100) in which the received signals are digitized at a clock cycle of the analog-to-digital converter (100), a digital filter (110) by means of which the digitized received signal is transformed into a complex-valued signal, and a multiplier (120) in which the complex-valued signal is multiplied by a complex-valued auxiliary signal.At the output of the multiplier (120) a complex-valued output signal in a baseband, whose frequencies are lower than the frequencies of the amplitude modulation, is obtained and the object detection signal is generated from the complex-valued output signal.