A FM coding, decoding and spreading method for visible light communication
A visible light communication, encoding and decoding technology, which is applied in short-distance systems, electrical components, electromagnetic wave transmission systems, etc., can solve the problem that the encoding efficiency is only 50%, achieve good consistency and simplicity, and simplify the table look-up steps.
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Embodiment 1
[0021] Embodiment one: see figure 1 — Figure 5 ,
[0022] The FM code decoding and code expansion method of visible light communication, the operation steps are as follows: Step 1: Encode the original data bits according to the FM method and add a single communication head, and drive the LED to emit light and send the code cyclically through the LED code driver. Step 2: The image receiving module shoots the LED light to obtain a light and dark coded stripe image. Step 3: The image processing module decodes according to the single communication head in the image to obtain data bits. Step 4, such as figure 1 As shown, when the coding capacity produced by single communication head coding is too small to meet the demand, the long data that meets the capacity requirements can be constructed, the long data is split into multiple short data, and each short data is coded by frequency modulation method And add different communication headers carrying sequence information, after de...
Embodiment 2
[0029] Embodiment 2: This embodiment is basically the same as Example 1, and the special features are as follows: see Figure 6 ,
[0030] If the working environment does not require high lighting, you can use "01" to represent the data bit "0", and its width scalar is 1, use "011" to represent the data bit "1", and its width scalar is 2, such as Figure 6 shown. Use the shortest communication head "0111", at this time the luminous flux modulation rate ranges from 50% to 66.7%, which can also play a lighting role. In this encoding situation, since the number of stripes that can be captured in a single image is fixed, using fewer stripes to represent one bit of data can lead to higher encoding capacity. The subsequent encoding and decoding process is the same as Example 1. Therefore, the number of 1s in the code can be increased or decreased according to the actual use situation in exchange for high illuminance or high code amount.
Embodiment 3
[0031] Embodiment three: see Figure 7-Figure 8 ,
[0032] When the coding amount of a single picture does not meet the requirements, different communication headers can be used to represent different segments of data, such as the communication header "01111" indicates high-order data, and "011111" indicates low-order data. However, if the two sets of codes are directly spliced, the left and right sides of the communication head may not be the same piece of coded data, and bidirectional traversal and decoding cannot be performed. For this reason, when the two consecutive frames of codes sent by the LED are codes of different segments, a 0 code needs to be added between the two frame codes to distinguish them. To distinguish it from the coded dark stripes in data area 0, the coded picture is as follows Figure 7 , 8 shown. When decoding, it is judged whether the left end of the effective maximum bright stripe is a 00 coded dark stripe, if yes, only right traversal decoding ...
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