Photon key based on CMI (coded mark inversion) coding

Abstract

The invention relates to a photon key based on CMI (coded mark inversion) coding, which comprises a microprocessor module, a code pattern conversion module and an optical signal transmission module, wherein the microprocessor module is used for setting an unlocking code, and outputting a digital signal of which the code pattern is an NRZ (non-return-to-zero) code according to the unlocking code; the code pattern conversion module is used for converting the NRZ code digital signal into a CMI code digital signal; and the optical signal transmission module is used for transmitting an information-containing optical signal according to the signal output by the code pattern conversion module. By arranging the code pattern conversion module in the photon key and converting the NRZ code digital signal into the CMI code digital signal with the code pattern conversion module, the CMI code has the advantages of no zero-frequency component, small low-frequency component and certain error correcting capability, and the information code stream has very strong clock component, so that clock information can be conveniently extracted from the signal, thereby lowering the code error rate of signal transmission.

Description

technical field [0001] The invention relates to a photon key, in particular to a photon key based on CMI coding. Background technique [0002] The internal ban system belongs to the category of public security system and is a high-tech security facility widely used. Optical signals are not easy to decipher and have high security, so they have been gradually applied in access control systems. Existing access control systems that use optical signals to transmit information include photonic door locks and photonic keys that cooperate with the photonic door locks. The photonic keys The photonic door lock analyzes the light signal by emitting a light signal containing information that is constantly blinking, so as to open or close the door. [0003] Digital baseband signals can appear in different forms of electrical pulses, and the existence of electrical pulses is called code pattern; the process of representing digital signal electric pulses is called code pattern encoding or...

AI Technical Summary

Problems solved by technology

At present, the photonic key usually directly uses the on-off key code (such as NRZ code) for data transmission. The disadvantages are: (1) in the code stream, the number of "1" codes and "0" codes is randomly changed, Therefore, random fluctuations (baseline drift) will also occur in the DC component, which brings difficulties to the judgment of the photon door lock; (2) in the process of encoding information, more codes of 0 or 1 may be generated, which may cause bit Synchronous information is lost, which makes it difficult to extract the given timing or produces a large timing error

For example, the existing baseband transmission system usually extracts the bit synchronization signal from the received baseband signal, but the bit synchronization signal depends on the code pattern of the code. There may be a 0 potential for a long time, making it difficult for the bit synchronization recovery system to guarantee the accuracy of the bit synchronization signal

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