11 results about "Spread spectrum modulation" patented technology

Method for transmitting digital data between a bottom hole assembly and a surface assembly of a drilling rig, wherein at least one of the bottom hole assembly and the surface assembly comprises a transmitting transducer actuatable to generate acoustic waves propagating in a drilling fluid and the other of the bottom hole assembly and the surface assembly comprises a receiving transducer configured to detect acoustic waves, comprising the following steps : processing in sequence the data by means of convolutional coding, an interleaving operation and at least one spread spectrum modulation technique, obtaining a processed digital signal; - converting the processed digital signal into an analog signal; - actuating the transmitting transducer in such a way as to generate, in the drilling fluid, acoustic waves that correspond to the analogue signal; receiving the analog signal through the receiving transducer; converting the analog signal into a received digital signal; - processing in sequence the digital signal received by means of at least one demodulation technique, one "de- interleaving" operation and one convolutional decoding, obtaining the received data.

The application discloses a three-level inverter harmonic suppression method based on zero vector symmetrical reconstruction and spread spectrum composite modulation, and the method comprises the following steps: step 1, signal acquisition and voltage instruction acquisition; step 2, spread spectrum modulation parameter setting; step 3, basic vector action time calculation; step 4, zero vector symmetrical reconstruction of vector sequence; step 5, switch time calculation and register updating; and step 6, PWM signal generation and system closed loop operation. The application realizes full-band suppression of inverter output PWM harmonics by deeply fusing the zero vector symmetrical reconstruction technology and the spread spectrum modulation technology. The application can be applied to a permanent magnet synchronous motor driving system powered by a three-level voltage source inverter, can simultaneously suppress the PWM harmonic amplitude near the odd carrier frequency and the even carrier frequency, effectively reduces electromagnetic vibration and noise, and has extremely high application value in the field of high-power inverters and motor drives.

The application discloses a SiC inverter modulation method based on secondary frequency modulation and double modulation waves, initializes system parameters, sets a reference switching frequency, a spread spectrum modulation frequency, a dead time and a nonlinear threshold of secondary frequency modulation, executes a secondary frequency modulation algorithm, performs phase accumulation based on a real-time switching frequency to generate a variable-frequency triangular carrier signal, executes basic SVPWM calculation, executes dynamic double modulation wave generation logic, and generates complementary drive pulses. The application effectively reduces the residence probability of the switching frequency at the extreme value, reduces the peaks at both ends of the frequency spectrum, makes the noise energy more evenly distributed in the entire frequency band, and thus obtains a better EMI suppression effect. Through the double modulation wave technology, the offset amplitude of the modulation wave is adjusted online according to the real-time frequency, and the accurate compensation of the dead zone error caused by the frequency change is realized. No matter how the switching frequency changes, the physical dead time of the system output is always locked at the set value.

The application provides a spread spectrum phase-locked loop control circuit and a control method thereof and a processor chip, and relates to the technical field of electronic circuits.The spread spectrum phase-locked loop control circuit comprises a spread spectrum modulation sub-module, a reference clock delay sub-module and a feedback sub-module; the spread spectrum modulation sub-module is connected with the feedback sub-module and the reference clock delay sub-module; the spread spectrum modulation sub-module generates a first adjustment signal, a second adjustment signal and a frequency division control signal based on a frequency division ratio signal; the feedback sub-module generates a modulated feedback clock based on the first adjustment signal, the frequency division control signal and a feedback clock; the reference clock delay sub-module generates a modulated reference clock based on the second adjustment signal and a reference clock; the second adjustment signal is calculated according to the difference between the clock periods of the modulated feedback clock and the reference clock; and the edges of the modulated feedback clock and the modulated reference clock are aligned. The spread spectrum phase-locked loop control circuit helps to reduce phase noise during spread spectrum and improve the frequency accuracy of the spread spectrum clock.

The application discloses a kind of robust fast secret channel construction methods for amplitude using CSS spread spectrum modulation, mainly solve the problems, such as the limited transmission distance and capacity of secret channel in the existing low-power wide-area network environment, steps include: the modulation method design of secret channel;Signal frame structure design and frame detection;The demodulation method design of secret channel;Analysis is carried out to the information loss in the demodulation process of secret signal.The application designs the LoRa physical layer secret channel modulated by amplitude using CSS spread spectrum modulation method, designs the modulation and demodulation method of secret channel, analyzes the information loss in the demodulation process of secret signal, constructs the robust fast secret channel, widens the construction scene of secret channel, and the operation method is simple and clear, has practical value.

This application relates to a covert communication method, computer device, and readable storage medium utilizing linear spread spectrum modulation of nonlinear chirped spread spectrum amplitude. The method includes nonlinear spread spectrum LoRa communication between a transmitter and a receiver via a legitimate channel. The covert communication method comprises: at the transmitter, performing covert chirped modulation of the legitimate channel amplitude based on a linear chirped spread spectrum modulation method to form a covert channel carrying covert information; embedding the covert channel into the legitimate channel to obtain a transmission signal containing both legitimate and covert information; at the receiver, receiving the transmission signal through a legitimate receiver and demodulating it using legitimate nonlinear chirped modulation to obtain legitimate information; and at the receiver, receiving the transmission signal through a covert receiver, processing it with covert chirped information, and then performing covert chirped demodulation based on a linear chirped spread spectrum modulation method to obtain the covert information. This application embeds covert information into a legitimate nonlinear spread spectrum LoRa channel, improving the parallel transmission capacity of covert information.

The application discloses a kind of space gravitational wave detection satellite intercommunication ranging integration method based on BOC modulation and related equipment, the present application is directly spread spectrum modulation for BOC modulation baseband signal after communication data, BOC modulation baseband signal is modulated to the mode of main laser by phase modulation, obtains modulated laser carrier, uses modulation laser carrier to carry out heterodyne interference, can not be constrained by space gravitational wave detection laser link optical power distribution, realize space communication transmission and inter-satellite absolute distance measurement, to realize the inter-satellite ranging function of inter-satellite laser interference, improve the accuracy of inter-satellite ranging;The present application utilizes the spectral splitting characteristics of BOC, concentrates the power of modulated signal on the sideband of the main carrier, greatly reduces the interference of modulated signal on the main laser interferometric measurement, improves the inter-satellite ranging accuracy, realizes the integration of inter-satellite communication and ranging under strict optical power constraint.The present application is widely used in space gravitational wave detection technical field.

There is provided an information processing device, an information processing method, and a program that enable a system including two speakers and one microphone to measure a position of the microphone. An audio reception block receives an audio signal including a spreading code signal obtained by performing spread spectrum modulation on a spreading code, the audio signal being output from two audio output blocks existing at a known positions, and calculates a position of an audio reception unit on the basis of an arrival time difference distance that is a difference between distances to the two audio output blocks based on an arrival time at which a peak of cross-correlation is detected. The present invention can be applied to a game controller or an HMD.

This invention belongs to the field of secure communication technology and discloses a secure spread spectrum communication method based on stream encryption. The invention includes a pre-encryption module, a constellation shaping module, a higher-order mapping module, a spread spectrum modulation module, a randomization module, and an editing module. The original binary data signal (I / O) is sent to the pre-encryption module for processing. The input of the constellation shaping module is connected to its output. The input of the higher-order mapping module is connected to its output. The first output of the higher-order mapping module is connected to the editing module, and its second output is connected to the first input of the spread spectrum modulation module. The second input of the spread spectrum modulation module is connected to the output of the editing module. The randomization module is connected to the output of the spread spectrum modulation module. This invention achieves strict data confidentiality through the interaction between the modules, significantly reducing the probability of detection by non-cooperative parties, and its structure is simple and easy to implement.