6 results about "Direct-sequence spread spectrum" patented technology

This application proposes a method and system for transmitting time synchronization signals based on general-purpose software-defined radio (SDR). The method includes: constructing a time synchronization signal data frame based on input time information; performing direct sequence spread spectrum (DSSS) on the time synchronization signal data frame to obtain a spread digital sequence; modulating and mapping the spread digital sequence into a digital baseband IQ signal; transmitting the digital baseband IQ signal to a general-purpose software-defined radio peripheral; processing the signal through the peripheral; transmitting it via an antenna; and performing time delay calibration on the system before transmission to compensate for internal system delays. This application, by employing a software-defined radio architecture combined with a high-precision clock reference, achieves software-based, general-purpose, and high-precision processing throughout the entire process of time synchronization signal generation, processing, transmission, and calibration. The overall approach offers multiple advantages, including high flexibility, high precision, high reliability, low cost, easy scalability, and open research potential.

The application discloses a kind of inter-satellite microwave measurement communication link signal generation and chain building method, comprising: generating transmitting signal based on direct sequence spread spectrum mode, and transmitting signal is divided into mutually orthogonal I branch and Q branch, and the spread spectrum code sequence of different length is modulated to two branches respectively;I branch is used as measurement branch, fixed modulation long code is used and binary offset subcarrier modulation mode is used, and measurement data frame with fixed frame length and information rate is loaded on I branch;Q branch is set to pilot mode or communication mode, short spread spectrum code is modulated in pilot mode and no data is loaded, long spread spectrum code is modulated in communication mode and communication data with configurable information rate is loaded;The start bit of spread spectrum code period of I branch and Q branch is aligned with the start bit of data frame header to the local maintained second pulse, and the generation of inter-satellite microwave measurement communication link transmitting signal is completed.The application can realize acquisition complexity and pseudo-range measurement accuracy under the condition of given bandwidth.

This application discloses a frequency offset tracking method, apparatus, device, and medium, relating to the field of wireless communication. The method involves receiving a burst direct sequence spread spectrum signal; generating multiple parallel frequency correction values ​​based on the burst direct sequence spread spectrum signal and a local carrier; wherein the local carrier is generated based on the burst direct sequence spread spectrum signal; despreading the multiple parallel frequency correction values ​​to generate corresponding multiple parallel correlation matching values; merging the multiple parallel correlation matching values; and performing frequency offset tracking using a frequency-locked loop method and the merged correlation matching values. Therefore, the above scheme performs parallel multi-path frequency offset correction on the received burst direct sequence spread spectrum signal and then performs frequency offset tracking using a frequency-locked loop method. This not only achieves high-precision frequency offset tracking but also adapts to large frequency offset change rates, enabling frequency tracking of burst direct sequence spread spectrum signals under high dynamic conditions.

The application discloses an APF multi-machine parallel system current sharing control method and system, a storage medium, and an APF multi-machine parallel system, which is composed of N single-phase APFs connected in parallel to an electric network and is used for compensating for harmonic currents and reactive currents of the electric network; a signal generation module generates a data signal by using a modulation method of direct sequence spread spectrum differential phase shift keying (DS-DPSK); a signal acquisition and demodulation module is used for collecting, filtering, despreading and demodulating an electric network voltage signal and restoring the same into a corresponding data signal; and a compensation control module adjusts a compensation coefficient to realize current sharing control according to the received data information. The application can realize power quality treatment, data transmission, current sharing control for reducing inverter loss and safe and stable operation.

This invention discloses a method for fast range ambiguity resolution of short-period direct-sequence spread spectrum signals used in radar measurement. The method comprises: 1) designing a square wave period based on the maximum unambiguous measurement range requirement; 2) transmitting a direct-sequence spread spectrum signal modulated with a square wave at the transmitting end; 3) estimating the code phase within the spread spectrum pseudocode period at the receiving end using fast circular correlation; and 4) despreading using the spread spectrum pseudocode phase estimation result and accumulating energy within the spread spectrum pseudocode period to obtain N. s The energy accumulation results are as follows: 5. The energy accumulation results within adjacent spread spectrum pseudocode periods are used to search for the square wave transition edge using a differential method to complete target detection decision and distance estimation; This invention can effectively improve the maximum unambiguous distance for capturing high dynamic weak signals, while resolving the contradiction between computing resources and acquisition time.