Rolling Shutter Camera LED Data Extraction via Start Frame Synchronization
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Solution Overview
Problem
Conventional image sensor communication systems using rolling shutter cameras face challenges in accurately extracting data due to unsynchronized frame rates, data loss, and weak signal strength, especially in long-distance transmissions, as they struggle to distinguish on/off images of LEDs effectively.
Innovation Solution
An image sensor communication system that employs a data coding unit to encode transmission data, an LED for on/off control, a rolling shutter camera for continuous image capture, and an image processing unit to generate brightness signals, along with a data extraction unit to accurately extract data using frequency division modulation (FDM) methods, ensuring reliable data transmission even with varying frame rates and long distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rolling shutter camera is used to photograph LED on/off images for data transmission, then data communication can be achieved, but accurate data extraction becomes difficult due to frame rate desynchronization between camera and LED switching
Solution Approach 1:
The patent applies periodic action by using a start frame signal that periodically marks the beginning of data transmission. The LED transmitter switches at regular intervals synchronized with this periodic signal, and the camera captures frames at corresponding periodic intervals, ensuring that data transmission always begins at a known point in the frame sequence regardless of camera frame rate variations
Solution Approach 2:
The patent implements feedback through the start frame mechanism that provides timing information back to the data extraction process. The detected start frame position feeds back into the extraction algorithm, allowing it to adjust and synchronize with the actual LED switching timing, thereby maintaining accurate data extraction even when frame rates differ between transmitter and receiver
2Adaptability or versatility
If the camera frame rate changes within the range of 20-35 fps, then adaptability to different camera products is improved, but data loss occurs when LED on/off transitions happen between captured frames
Solution Approach 1:
The patent applies preliminary action by pre-marking the start of data transmission with a distinctive start frame signal before the actual data is transmitted. This preliminary marker allows the receiver to identify the exact beginning of the data sequence, ensuring that even if the camera captures frames at variable rates, the complete data sequence can be reliably extracted without loss by knowing where it starts and ends
3Ease of operation
If the LED and camera are positioned at long distances apart, then installation flexibility is improved, but signal strength becomes weak making on/off image distinction difficult
Solution Approach 1:
The patent uses periodic action with the start frame signal to structure the transmission in recognizable cycles. Each transmission begins with a periodic start marker that creates a distinct temporal pattern, allowing the receiver to identify and extract data even when the LED signal is weak due to long distance, because the periodic structure provides clear temporal boundaries for detection
Solution Approach 2:
The patent applies parameter changes by modifying the temporal characteristics of the LED signal through the start frame structure. By encoding timing information and using periodic on/off patterns synchronized with frame capture, the system enhances the distinguishability of the signal even at low illumination intensities, allowing long-distance transmission while maintaining data extraction accuracy
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 system ensures accurate data extraction and transmission by synchronizing data frames, preventing data loss, and enhancing signal strength through frequency-modulated signals, enabling reliable communication even at long distances and with unstable frame rates.
Implementation Method 1
an LED turned on/off according to the transmission data coded by the data coding unit
Implementation Method 2
a rolling shutter camera for continuously photographing on/off images according to on/off of the LED
Data Source
AI summary
The present invention relates to an image sensor communication (ISC) system and method for enabling communication between an LED and a rolling shutter camera using a rolling shutter modulation method. The image sensor communication system according to an embodiment of the present invention comprises: a coding unit for coding transmission data to be transmitted; an LED which is turned on/off according to the transmission data coded in the coding unit; a rolling shutter camera for continuously photographing, at each of a plurality of rows in a rolling shutter manner, on/off images according to the on/off of the LED; an image processing unit for generating brightness signals according to brightness values of the on/off images of the LED photographed at each of the plurality of rows by the rolling shutter camera; and a data extraction unit for extracting the transmission data from the brightness signals of the on/off images of the LED generated by the image processing unit.