Optical camera communication demodulation method supporting receiver shaking and user movement

Abstract

The invention relates to an optical camera communication demodulation method supporting receiver shaking and user movement, and the method comprises the following steps: obtaining an LED fringe video carrying original sending data, and extracting each frame of fringe image; graying and binarizing the stripe image, and extracting edge features to obtain a binarized stripe image; converting the binarized stripe image into a regular stripe image, and then recovering data of the regular stripe image by adopting a stripe area demodulation method; and adopting manchester encoding in the original sending data, wherein pilot frequency information is contained in a data packet. According to the invention, the influence of the blooming effect on the data can be ignored, environmental noise can be resisted more easily, the communication rate is increased, the problems of randomness and shaking movement of multi-user shooting positions are solved, the method has the characteristics of low complexity, high noise resistance and the like, and data signals can be recovered more easily and accurately.

Description

technical field [0001] The invention belongs to the technical field of visible light camera imaging communication, and relates to a demodulation technology for solving receiver shaking or user movement by using the area of ​​bright and dark stripes obtained by photographing a light source using the rolling shutter exposure characteristics of a smart phone camera. Background technique [0002] With the continuous development of science and technology, the technology applied to OCC (Optic Camera Communication) by smart phones is becoming more and more mature. CMOS uses a Rolling Shutter Mechanism, and the rolling shutter exposure effect adopts a progressive exposure method. Using this feature can increase the data rate of visible light imaging communication. At each moment, the CMOS image sensor has only one row of exposure. When all rows of the image are exposed, the data of all rows of exposure captured at different times are combined to form an image. This row-by-row exposu...

AI Technical Summary

Problems solved by technology

Studies have shown that this type of communication system is relatively sensitive to the user's position and local shaking. However, in actual operation, the randomness of the user's receiving position and the shaking of the receiver or user movement during the shooting process will bring inaccurate data information.

In addition, in the OCC system, due to the progressive scanning characteristics of rolling shutter exposure, the number of pixel columns corresponding to each stripe decreases with the increase of the system bit rate. When using conventional demodulation methods for demodulation, the number of pixel columns The average value of the gray level fluctuates as the bit rate increases, making it impossible to obtain accurate data information

For example, the current threshold-based discriminant demodulation algorithm, its demodulation performance is susceptible to environmental noise (such as uneven illumination) and the above-mentioned excessive fluctuation of the average value of the column gray level, and the demodulation method cannot Solve the problem that the user is in a random position and shakes and moves; in addition, the current demodulation algorithm based on the width of the stripes is judged by calculating the number of pixels occupied by the stripes. However, in the actual operation process, due to the existence of environmental noise and each The number of pixels occupied by stripes is very small. In the case of high speed, it is extremely susceptible to noise interference, so it cannot improve the communication speed. The two mainstream demodulation methods mentioned above are based on single-point pixels. Modulation and decoding, its bit error rate is high, and its anti-noise performance is poor

[0003] At home and abroad, there are few researches on the application of OCC technology in actual scenes and innovative demodulation algorithms for different shooting angles of users, and there are corresponding technical gaps.

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