The invention provides a high-sensitivity GNSS carrier tracking loop optimization method. The method is used for satellite navigation signal carrier signal tracking optimization. The method comprises:when the GNSS completes signal capture, entering a frequency locking loop for processing and executing a high-sensitivity bit synchronization processing method at the same time, under the condition that Doppler residual frequency exists, achieving data message bit edge detection, after the edge is determined, further prolonging the integration time, and improving the sensitivity of the phase locking loop. According to the method, cross-message partial coherent accumulation is carried out after conjugate multiplication is carried out before and after the accumulation amount output by the correlator, and then cyclic correlation is carried out on the cross-message partial coherent accumulation and the constructed message hopping sequence, so that message hopping edge detection is realized. The method serves as a GNSS receiver high-dynamic high-sensitivity carrier tracking loop optimization method, and is suitable for capturing other spread spectrum signals.

High-sensitivity GNSS carrier tracking loop optimization method

The invention discloses a femtosecond laser-induced breakdown spectrum generation and acquisition system based on space-time shaping, and belongs to the technical field of femtosecond laser application. A Bessel light beam with a long focal depth is used for exciting material plasmas after being shrunk; under the condition that focusing is not carried out, plasma excitation with the same energy density is achieved at different height positions of a sample, the process of single-point independent focusing is omitted, possible human and machine errors in each time of focusing operation are avoided, and the stability, repeatability and collection efficiency of spectrum collection are guaranteed. The system can adjust parameters of the conical lens and the beam shrinking lens group to obtain Bessel regions with different focusing lengths, and a device suitable for samples with different height change ranges is designed according to individual requirements. When a femtosecond laser Bessel beam is adopted to excite plasmas on the surface of a rough sample, the combination of a half-wave plate and a Glan-Taylor prism in the system realizes the continuous linear adjustment of pulse energy,and realizes the sample detection and analysis under the nearly lossless condition.

Wang Sumei

Papers

Femtosecond laser-induced breakdown spectrum generation and acquisition system based on space-time shaping