Research On Acquisition Algorithm Of High Sensitivity GPS L1/L2C Software Receiver

In recent years, with the continuous improvement of the user to positioning requirements, GPSpositioning technology in weak signal environment becomes a research focus, with the addition ofthe good development of GPS modernization and software receiver, GPS receiver of doublefrequency becomes a trend. As the first part of signal processing in the receiver, signal acquisitionis very important. The dissertation studied the high sensitivity acquisition algorithm of the L1andL2C signal GPS software receiver and achieved certain results.GPS L1C/A code signal and L2C signal with adjusted ratio of the carrier to noise wererealized, which provide reliable source to the acquisition experiments.A new acquisition algorithm of weak L1C/A signal was studied. According to the deficiencyof the traditional algorithm, because the coherent integration which uses the data segments thatuse fusion of first summation then relevance idea can reduce the computational complexity, andthe improving semi-bit acquisition method can avoid navigation data bit transition, the improvingdifferential correlation method can reduce “square loss” which produced by non-coherentintegration and improve the signal to noise ratio, a new algorithm was proposed which merges allthe advantages. The simulation experiments show that the speed of the new algorithm increasedby ten times and the time is only2.4s, it can capture the weak signal of25dB/Hz and7satellites.Two suitable acquisition algorithms of the L2CM code signal in the indoor environment werestudied. Based on the processing of data with “first summation then relevance”, the traditionalCNC algorithm and differential coherent integration algorithm were improved. The experimentsshow that the two algorithms can capture the weak signal of30dB/Hz and the later can reduce thenoise and improve the signal to noise ratio.A kind of algorithm to L2CM signal making use of acquisition information of L1C/A codesignal was studied. Using the acquisition information of L1can know the Doppler frequency shiftand the CM’s general scope of L2. Combined with the improved differential coherent integrationalgorithm, a new auxiliary acquisition algorithm was proposed. The experiments show that thealgorithm can capture the weak signal of35dB/Hz and the acquisition time is only3s, it greatlyimproves the signal capture speed.A kind of L2CL code signal acquisition algorithm guided by the acquisition information ofCM was introduced. The experiments show that it can capture the CL code phase quickly andefficiently.