Pseudo Code Capture Method Research Based On Compressed Sensing Technology

With the development of the satellite navigation technology, it has played a huge role in the field of civil and military: for air, sea, highway, rail transport vehicles,It provides precise location information;for geodesy, underwater topographic survey, crustal deformation,It provides measurement service; for electricity, communications,base stations,It provides accurate timing services and so on. Because of its huge role, at present, lots of countries are scrambling to developing their own satellite navigation system. The United States, which is the first GPS satellite launch country, is into the third generation of the satellite era now.China is developing its own Beidou satellite positioning system, which is expected to complete in 2020 to achieve global coverage precise positioning. The EU and Russian are also rapidly developing its own Galileo and GLONASS system.In order to achieve the accurate positioning for the user, Capture Technology is a key link of the receiver. At present capturing signal is mainly through two methods, one kind is serial linear capture method, the other one is parallel code phase capture method. But both methods wiil require a high signal sampling frequency and will take up a lot of storage resources. In recent years,it has produced a kind of brand-new technology,Compressed Sensing,in digital signal processing field. Once the technology is proposed ,it attracts a great deal of attention and response. The technology combines sampling and compression process,measures the original signals through the non- adaptive coding and restores the original signal through the reconstruction algorithm. The Compressed Sensing Technology is applied to the satellite signal capture. It shortens the time for the data acquisition and reduces the amount of data transmission and storage,so it has a strong research and application value.In this paper, the specific work arrangement is as follows: first of all, the composition of the GPS signal is introduced in detail and the common GPS signal capture method is studied.And then the three important parts of Compressed Sensing Technology is studied: sparse representation of the signal, the condition of choosing measurement matrix and common reconstruction algorithm. For traditional GPS reception model contains a large amount of redundant information, choosing the carrier multiply the PN code as a sparse base can make the signal satisfying sparse conditions under the representation of sparse base. Considering though the random gaussian matrix and sparse base have good irrelevant features, it is not convenient to store, selecting random binary matrix,a kind of the Bernoulli matrix,as measurement matrix. It is convenient to store and can achieve good effect of projection. The reconstruction algorithm of Compressed Sensing Technology is one of research hot spots.Though there are many reconstruction algorithms, the relatively mature algorithm is only OMP algorithm. So the pseudo-code capture based on compressed sensing framework uses the OMP algorithm to implement reconstructing the measurement signal . Finally using FPGA embedded system to set up the signal capture processing modules and designing the hardware modules to realize the OMP algorithm.