Design And Implementation Of Signal Simulator In Navigation Test

With the development of science and technology,navigation system has become an important part of people’s daily life,national social and economic development.The test of navigation equipment is complex and responsive.So the testing system of navigation becomes the best choice for the test of navigation system.Signal simulation equipment provides excitation signal for the automatic test system,which is an indispensable part of it.The Global Positioning System GPS was used as an example in this thesis.A signal simulation device of L1 frequency point signal of GPS satellite was designed for GPS receiver testing.The main contents of the thesis are as follows:1.Analysis of signal simulation element information: The step of updating parameters was analysed on the format and propagation environment of L1 signal.The overall design was given,which is based on the software radio platform of zero-IF quadrature modulation.2.The design of the hardware circuit of the signal simulation equipment: The hardware is consisted of RF transceiver circuit,baseband processing circuit,clock generation circuit,power supply circuit.The specific implementation plan is determined.The zero-IF RF transceiver AD9361 was used to build the RF part of the software radio hardware platform.This hardware platform has a small PCB area.The baseband processing unit uses the FPGA+ARM architecture to meet the design’s demand for high update rate of signal parameters.3.The design of logic of the signal simulation equipment: Logic design includes interface timing logic module,propagation simulation logic module,coding logic module and other modules.The code NCO and the carrier NCO are used to simulate the propagation delay and Doppler frequenc.The test verifies that this signal simulator can generate the L1 signal of GPS satellites,and the frequency offset and phase offset are adjustable following the relative speed and distance.The test results verify the feasibility of the design scheme.