51 results about "Chaos communications" patented technology

A chaotic communication system employs transmitting and receiving chaotic oscillating circuits. In an embodiment of the invention employing a Chua circuit as the basic chaotic circuit, the transmitter has a tank circuit portion and a Chua diode portion linked through a resistance. The capacitance of the tank circuit is varied by selectively switching in and out of the tank circuit an auxiliary capacitance isolated by an optoisolator. Switching of the optosiolator is controlled by an information signal to generate a perturbed oscillation in the transmitting circuit. A voltage is tapped from the Chua diode circuit and transmitted to carry the information from the information signal. A receiver in another embodiment applies the transmitted signal to both the tank circuit and Chua diode portions of the receiving circuit. The transmitted signal is applied through a resistor to the Chua diode portion as well as the tank circuit portion. By applying the received signal to the Chua diode portion as well as the tank circuit, synchronization of the transmitter with the receiver is accelerated substantially. In still another embodiment, the tank circuit components are varied to generate a vocabulary of chaotic signals that can be decoded by various receiver embodiments that are described.

The present invention teaches method and apparatus to transform a featureless, unpredictable, and non-repeatable chaos waveform into digital chaos waveforms that maintain featureless characteristics to serve as a for wireless communications protocol, whereby unintended observers cannot detect or disrupt yet imprint a small measure of predictability and repeatability to aid intend observers in recovering embedded information.

The invention provides a wavelength-hopping chaotic secure communication method and system based on multi-mode lasers and belongs to the field of secure communication. The system comprises a driving end and two two-way-coupled sending/receiving ends. The same external chaotic optical injection signals are provided for the sending/receiving ends through the driving end, so that chaotic synchronization of each mode of the multi-mode lasers of the sending/receiving ends is achieved, information is loaded into chaotic carrier waves of different modes of the lasers of the sending/receiving ends in different time slots, and two-way wavelength-hopping transmission of the information is realized. The method and the system utilize the enhanced information security features of chaotic communication technology and wavelength-hopping technology at the same time, can improve the physical-layer information transmission security, and is applicable to high-security communication services. Meanwhile, as the method and the system achieve multi-wavelength chaotic synchronization based on the multi-mode lasers, and the information secure transmission capacity of the system can be improved.

The invention provides a time delay hiding and frequency spreading system based on laser chaos self-modulation and a method for generating laser chaos through employing same. The system comprises a chaos external cavity semiconductor laser and a frequency spreading module. A chaos optical signal generated by the chaos external cavity semiconductor laser passes through the frequency spreading module for frequency spreading conversion, thereby achieving the flat and wide spectrum and the time delay hiding of the laser chaos signal, wherein the frequency spreading module consists of a drive signal, a photoelectric phase modulator and an FBG (Fiber Bragg Grating). The above time delay hiding and frequency spreading system enables the safety of the chaotic communication to be greatly improved.

The invention belongs to the technical field of chaotic communication carriers, particularly relates to a broadband white chaos generation method and device. The problems that a traditional white chaos generation device is complex in structure, high in cost, single in generated white chaos bandwidth and not high in adjustability are solved. According to the method, a VCSEL chaotic generator is used for outputting a total chaotic signal; a total chaotic signal is divided into two paths of optical signals through a polarization beam splitter; the polarization states of two paths are adjusted tobe consistent, the optical frequency difference is adjusted between 10 GHz and 20 GHz, frequency beating is conducted on the two paths, optical signals obtained after frequency beating are divided into two paths with the equal power intensity, balance detection is conducted on the two paths of optical signals through the equal optical path, and difference signals are converted into electric signals. The device comprises a VCSEL chaotic generator, a polarization beam splitter, a first polarized light detector, a second polarized light detector, a tunable polarization controller, a 2 * 2 opticalfiber coupler and a balance detector. The device is simple in structure and low in equipment cost, and broadband white chaotic bandwidth adjustment can be achieved through the method.

The invention relates to a differential chaotic communication method and system based on polarization codes. The method comprises a coding modulation process and a demodulation decoding process. The code modulation process comprises the following steps: after a signal source generates a signal, inputting the signal into a polarization code encoder for encoding, then sending a code word encoded bya polarization code into a DDCSK-WC modulator for chaotic modulation, redesigning a data frame by utilizing an orthogonal Walsh code, and sending the redesigned data frame; wherein the demodulation and decoding process comprises the steps that after a receiving end receives a signal, a DDCSK-WC demodulator demodulates the received signal, soft information obtained through demodulation is input into a polarization code decoder, the polarization code decoder decodes the soft information through an SC decoding algorithm based on an MS algorithm, and finally a decoding result is obtained. According to the method and the system, the information transmission rate and performance of communication are improved, and the calculation complexity and the implementation cost are reduced.

The invention provides a high-efficiency and energy-saving differential chaos communication scheme. The scheme belongs to the field of communication systems. Through effective improvement of a prior frame structure of a DCSK system, transmission time of each frame is shortened. The DCSK system subjected to transformation remains a prior frame structure; the reference time slot length is changed to1/P(P=beta/R) of the prior length and the data time slot length remains the same. The frame structure is composed of P times duplication, which carries 2 bit information, of the sum of the referencetime slot and the reference time slot of the last frame. A demodulation terminal adopts a non-coherent demodulation method. In order to demodulate each bit of information, a synchronization clock is adopted. The received reference time slot is correlated to the corresponding data time slot and finally sending information is acquired through demodulation with a judgment threshold. Namely, if the correlation value is greater than zero, +1 is judged; if the correlation value is not greater than zero, -1 is judged. The scheme provided by the invention achieves higher transmission rate than a DCSKsystem. At the same time, lower bit energy is consumed compared with the DCSK system. Good performance of SERT-DCSK enables a good application prospect in the wireless communication field.

The invention discloses an OFDM-DCSK (Orthogonal Frequency Division Multiplexing-Differential Chaos Shift Keying) communication system and relates to the wireless communication field. The purpose of the invention is that the data rate is increased in the OFDM-DCSK communication system to solve the delay problem of RF (radio frequency). As an irrelevant chaos communication solution, all subcarriers are divided into several groups, chaos reference sequences are transmitted by the central subcarrier in each group, and modulated data streams are transmitted by the subcarriers in the residual groups. Thus, in comparison with a traditional DCSK system, the spectrum utilization rate is improved by a transmitting structure. The received data on a receiving end isn't demodulated by a radio frequency delay circuit, so that a convenient condition is provided to the system in practical application. The system is applied to wireless communication occasions.

The invention discloses a transmission system based on coupled lasers for chaotic broadcast communication. The transmission system comprises a first laser, a second laser, a first plane mirror, a second plane mirror, a first collimating lens and a second collimating lens, wherein the second laser, the first laser, the first collimating lens and the first plane mirror are sequentially arranged, thesecond laser, the second collimating lens and the second plane mirror are sequentially arranged, the second laser is served as a transmitting end, and the first laser is served as a receiving end. According to the transmission system, the information of the sending end is received by utilizing the receiving laser so as to realize broadcast communication in a chaotic communication field, when boththe lasers of the transmitting end and the receiving end send '0' or '1', the two lasers are synchronous, and otherwise, the two lasers are in an asynchronous state; and the modulation and demodulation processes of the transmitting end and the receiving end of the broadcast transmission system are bits transmitted by the transmitting end decoded by means of the power error between the received information and the local information, so that the purpose of broadcasting information from one laser to another laser is achieved.

The invention relates to an electro-optic phase mutual coupling bidirectional chaotic communication system, which comprises a transmitting end and a receiving end which are connected through an optical fiber, the transmitting end comprises a first chaotic laser, a first beam splitter, a first circulator, a first coupler, a first Mach-Zehnder interferometer, a first photoelectric detector, a first electric amplifier and a first phase modulator which are connected in sequence; the system further comprises a second chaotic laser, a second circulator, a second Mach-Zehnder interferometer, a second photoelectric detector and a second electric amplifier which are connected in sequence, the second electric amplifier is connected with the first phase modulator, and the first circulator and the second circulator are both connected with the second coupler. The second coupler and the first phase modulator are connected with the third circulator; and the receiving end and the sending end have the same structure. The chaotic communication system not only realizes chaos time delay hiding of chaos synchronous communication, but also has the characteristics of stable performance, high confidentiality and the like.

The invention discloses a device and a method for enhancing the safety of a co-driven chaos synchronization system, and relates to the technical field of chaos communication carriers, and the device comprises a transmitting end, a first receiving end, a first dispersion compensation device, a second receiving end and a second dispersion compensation device. The transmitting end generates a main chaotic signal, divides the main chaotic signal into a first path of main chaotic signal and a second path of main chaotic signal, and sends the first path of main chaotic signal and the second path of main chaotic signal to the first receiving end and the second receiving end; a first receiving end receives a first path of main chaotic signal, and after the first path of main chaotic signal is processed by a first dispersion compensation device, a first path of slave chaotic signal is generated; and the second receiving end receives the second path of main chaotic signal, and after the second path of main chaotic signal is processed by the second dispersion compensation device, a second path of slave chaotic signal is generated to realize chaotic synchronization with the first path of slave chaotic signal. According to the invention, two paths of chaotic signals with flat frequency spectrums and no time delay characteristic can be generated, high-quality chaotic synchronization is realized, and the safety of a co-driven chaotic synchronization system is improved.