Capture algorithm and system for QV-band low-orbit satellite spread spectrum communication

The invention discloses a capture algorithm and system for QV frequency band low orbit satellite spread spectrum communication, and relates to the technical field of satellite communication. According to frequency offset compensation values of different signals, determining whether the preprocessed signals enter a capturing process or a tracking process; a capturing process is firstly carried out, and de-spreading and differential processing are carried out; performing segmentation division and coherent accumulation summation on the basis of the processed signal sample, converting the signal sample into a frequency-time domain matrix, and performing two-dimensional correction processing to obtain a Doppler-code phase matrix; next, peak condition judgment is carried out on the Doppler-code phase matrix; if the judgment condition is not met, obtaining a frequency offset compensation value by polling a Doppler frequency offset value, and returning to the preprocessing step to continue the capturing process; if t