30 results about "Chaotic modulation" patented technology

A chaotic communication system employs transmitting and receiving chaotic oscillating circuits. One improvement to first-generation systems is the ability to modulate a nonreactive element in the transmitting circuit, thus increasing modulation bandwidth. Other features include insertion of a gain control amplifier in a chaotic receiver; signal filtering in chaotic transmitters and receivers; use of chaotic modulation techniques for cellular telephony applications; dual-transmitter and receiver systems; a dual receiver synchronization detector; interfaces to communication systems; analog chaotic signal modulation; use of multiple chaotic transmitters and receivers; digital algorithm improvement using a cube-law nonlinear component; a Gb-only receiver; a Gb-only transmitter; and positive slope transmitter and receiver systems.

A method and apparatus to generate a pulse width modulated signal from a sampled digital signal by chaotic modulation. The method includes generating predetermined chaotic intervals having random interval values using a chaotic interval generator, and generating the pulse width modulated signal from a reference signal and the sampled digital signal during each of the chaotic intervals. Thus, electromagnetic interference (EMI) that affects an audio amplifier can be remarkably reduced.

The invention relates to a different-dimensional switchable chaotic system design method and a circuit; a four-dimensional hyper-chaos system is constructed by adding variables and feeding back control items based on a three-dimensional generalized Lorenz system family; and a switchable different-dimensional chaotic circuit is designed through a plurality of switch controllers in Multisim software. An analog circuit constructed by the invention is convenient to use and easy to realize by hardware, and has relatively lower cost; the designed switchable circuit not only can flexibly realize the switching between a three-dimensional chaotic system and the four-dimensional hyper-chaos system, but also can return to realize the switch among three chaotic systems in the same dimension; and the systems can serve as practical chaotic modulation and chaotic encryption signals, and can be widely applied to the field of information security cryptography with higher requirements on confidentiality and reliability.

The invention discloses a blind estimation bit synchronization method for a differential chaotic modulation communication system and relates to a bit synchronization method based on the chaotic spread spectrum technology in the field of digital mobile communication. The invention provides the blind estimation bit synchronization method for the differential chaotic modulation communication system. In the blind estimation bit synchronization method, the characteristics of carrier waveform repetition and energy conservation of reference and modulation parts in a differential chaotic modulation signal are utilized, a local relative maximum value which is more than a synchronous threshold is searched and is used as an initial synchronization point of a local clock, and a digital phase-locked loop is used to perform the tracking synchronous adjustment of subsequent relative peak value, so that the establishing speed and accuracy of the bit synchronization are considered.

The invention discloses a chaotic modulation-based phase-sensitive optical time domain reflection vibration detection device, which belongs to the technical field of distributed optical fiber sensing.According to the technical scheme adopted to solve the technical problem, the device adopts a chaotic laser to carry out chaotic modulation on highly-coherent optical signals, the optical signals arethen injected to a sensing optical fiber, correlation operation is carried out on Rayleigh scattering optical signals generated in the sensing optical fiber and reference signals, and a vibration position is acquired. The device can be widely applied to a long-distance and high-definition distributed vibration detection field.

The invention discloses a chaotic secret optical communication system based on double random phase encoding, and the system comprises a transmitting end which carries out the intensity modulation of achaotic optical signal and secret data; the double random phase encoding device comprises a first phase modulation module, a dispersion device and a second phase modulation module; the first phase modulation module is driven by a random key sequence A; different first phase codes are dynamically applied to the chaotic modulation signal in a time domain, then the chaotic modulation signal enters adispersion device and interacts with the dispersion device, through phase-intensity conversion of the dispersion device, intensity distribution of the chaotic modulation signal is disturbed in the time domain, and the waveform of the chaotic modulation signal is converted into a random-like noise signal; and the second phase modulation module is driven by the random key sequence B, performs second phase encoding on the chaotic modulation signal, and performs phase disturbance on the chaotic signal. According to the invention, the security of the secret data of the chaotic sending end is significantly enhanced.

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 discloses a method and device for generating low coherent light by wideband chaos modulation in laser display, and relates to the field of laser modulation application of a chaos circuit. The method is specially characterized in that a wideband chaos light source gives out a light source signal, the light source signal is input to a high-speed photoelectric detector, a wideband chaoselectrical signal is generated and then is amplified by a wideband amplifier, the wideband chaos electrical signal is input to a bias device, a driving voltage of a laser driving circuit is also input the bias device and is mixed with the chaos signal amplified by wideband, power is supplied to a plurality of lasers for laser display so as to drive the lasers to work, meanwhile, the chaos modulation signal is also output, each signal is input in parallel to the modulation laser and passes through a circuit with delay larger than 0.3ns or 6cm, each laser outputs chaos laser, no coherence is generated when an output signal reaches a screen end, namely low coherent light output is obtained, the light is converged by a convergent lens, is collimated by a collimating lens and is injected to anMEMS lens in parallel, and the imaging of a laser display system on a screen is achieved by adjustment of a corresponding scanning circuit.

The invention discloses a chaotic modulation speckle-free laser projector. The laser projector comprises a plurality of sets of laser device arrays, a laser device array driving device, a laser outputpart and a projection unit, wherein each laser device array is composed of a plurality of same-color laser devices; a respective convergent lens and a collimating lens are arranged behind each set oflaser device array along the light path, and the laser output part and the projection unit are arranged behind all the collimating lenses; the laser device array driving device comprises a chaotic electric signal generation device and a laser device driving circuit, the output end of the chaotic electric signal generation device is connected with the input end of a broadband amplifier, the broadband amplifier is output to a bias device, and the laser device driving circuit is output to the bias device; the bias device drives each laser device of the multiple sets of laser device arrays to emit light through a line with the delay larger than 0.3 ns or larger than 6 cm. The full-power output of the laser devices is guaranteed, speckles of the laser devices are inhibited, and the projectioneffect of the projector is better.

The digital phonetic chaotic secret communication system consists of phonetic coding circuit and phonetic decoding circuit, and features that the phonetic coding circuit encodes the phonetic signal into electronic signal, the chaotic modulator completes the signal modulation, the chaotic demodulator demodulates the received signal and the phonetic decoding circuit decodes and output the signal.

The present invention discloses a circuit fault detecting method using chaotic power supply source current, comprising the following steps: step 1: using a chaotic circuit as a power supply source for a tested circuit; step 2: applying the trunk current of the chaotic circuit to encode the fault of the tested circuit and inputting the tested circuit; and step 3: decoding the output of the tested circuit, wherein the obtained fault characteristics correspond to the inputted fault one by one to form a fault dictionary and the two ends of the tested circuit are provided with an upsampling circuit and a downsampling circuit respectively. According to the invention, through the constructing of a chaotic modulation power supply source and the defining of the trunk current parameters of the chaotic power supply source, it is possible to realize the detection of the circuit fault and to achieve the advantages of direct graphic solution and obvious contrasts as well as accurate fault location.

The invention is a high-power remote-control dimmable high-voltage sodium lamp driver comprising a filter rectifier circuit, an active power factor correction circuit, an HID small signal processing and protection circuit, a remote control module, a half-bridge inverter circuit and a pulse ignition circuit. The input terminal of the filter rectifier circuit is connected with 220-V commercial power and the output terminal of the filter rectifier circuit is connected with the active power factor correction circuit. According to the invention, on the basis of the two-stage-structure high-frequency drive circuit, an acoustic resonance problem is solved by chaotic modulation; with the STM32 control operation, connection or disconnection, gradient dimming, remote control, real-time monitoring and other functions of the high-voltage sodium lamp are realized; and the reliability of the drive circuit is improved and the energy is saved.

The invention discloses a method and a device for eliminating speckle in laser display by a chaotic circuit modulating laser. Specifically, after a chaotic circuit generates a broadband chaotic electrical signal, the broadband chaotic electrical signal passes a broadband amplifier, then the signal is inputted into a biasing device, a driving voltage of the laser driving circuit is also inputted into the biasing device and is mixed with the chaotic electrical signal which is subjected to broadband amplification to supply power to multiple lasers for laser display to drive the lasers to work, atthe same time, a chaotic modulation signal is also outputted, the signals are connected in parallel to modulate the laser, through a line with a delay larger than 0.3 ns or larger than 6cm, each laser outputs chaotic laser, at the same time, an output signal has no coherence when reaching a screen end, which means no-speckle beam output is obtained, the light outputted by the lasers is concentrated by a converging lens, the light is collimated by a collimating lens and then is parallelly injected into a MEMS lens, and the imaging of the laser display system on a curtain is achieved through corresponding scanning circuit adjustment. According to the method and the device, the full power output of the lasers is ensured, the energy utilization rate is improved, and the system is simple and reliable.

The present invention discloses a chaotic frequency modulation digital switch power control circuit based on the FPGA. The circuit comprises a PID duty ratio parameter calculation circuit, a chaotic sequence generation circuit, a chaotic signal processing circuit and a digital pulse width modulation circuit; the PID duty ratio parameter calculation circuit is electrically connected the digital pulse width modulation circuit; the chaotic sequence generation circuit is electrically connected with the chaotic signal processing circuit; the chaotic signal processing circuit is electrically connected with the digital pulse width modulation circuit; and the digital pulse width modulation circuit is electrically connected with circuit output signals. The circuit can achieve chaotic modulation ofthe digital switch power switching frequency, is controllable in the modulation range, can inhibit the electromagnetic interference of the digital switch power source and can be used for the digital switch power control chip design.

An all-digital spread-spectrum type communications system employing chaotic symbol modulation. The system includes a transmitter having a symbol mapper that converts a series of information bits to a series of bit symbols, a digital chaos modulator employing an M-ary chaotic shift keying (M-CSK) architecture for chaotically spreading the bit symbols in the digital domain, where the chaos modulator includes a separate chaos generator for each of the M-CSK symbols, and a digital-to-analog converter (DAC) for converting the chaotic modulated bit symbols to an analog signal for transmission. The system also includes a receiver responsive to the analog signal from the transmitter and generating a received signal therefrom. The receiver performs signal acquisition and tracking on the received signal using a look-up table, a transmitter ID and a receiver ID in the received signal, de-spreading and de-modulation on the received signal and bit removal from the symbols in the received signal.

The invention provides a linear regular domain voice encryption system based on cascade chaotic modulation, and belongs to the technical field of voice communication encryption. Comprising a voice signal acquisition module (1), a linear canonical transformation module (2), a cascade chaotic system module (3), a transform domain encryption module (4), a linear canonical inverse transformation module (5) and an encrypted voice storage module (6). By arranging the cascaded chaotic system module, the chaotic Lyapunov index can be improved, the key space is expanded, and the safety performance is improved; the used linear canonical transformation acts on segmented signals through chaotic modulation and dynamic change of the cascaded chaotic system module, the complexity of an encryption algorithm can be increased, the cracking difficulty of the algorithm is improved, and the safety of voice signals is improved.

The invention provides a feedback type active EMI filter optimization method suitable for a PWM converter, and the method comprises the following steps: carrying out chaos spread spectrum modulation in the PWM converter, and obtaining a common-mode EMI frequency spectrum, which needs to be attenuated, of the PWM converter through a linear stable impedance network; analyzing a common-mode EMI path of the PWM converter, and designing parameters of an active EMI filter according to a principle topology of the active EMI filter; and according to the original and chaos modulated EMI amplitudes, determining a gain required by an operational amplifier, determining an effective bandwidth, and measuring a filtered common-mode EMI spectrum. According to the method provided by the invention, the characteristic that the EMI frequency spectrum is reduced by using chaos spread spectrum modulation is combined with the design of the active EMI filter, so that the operational amplifier gain required by the active EMI filter is reduced, the effective bandwidth of the active EMI filter is widened, and the high-frequency EMI suppression effect of the active EMI filter is improved.