Software Design Of GNSS Digital Intermediate Frequency Signal Source

Signal source of software GNSS (Global Navigation Satellite System) is used togenerate satellite navigation signal of multiple constellation and signals system,it providesa highly efficient tool for simulation of satellite navigation system and test of thereceiver,and it has very important practical significance on the establishment anddevelopment independent satellite navigation system in our country. This article presentsthe overall train of thought about designing GNSS signal simulator and shows the resultsof experiment.The thesis makes a deep research in some key technologies of GNSS signal simulator,taking a way of model algorithm and combining system implementation.First of all, it establishes the signal model of the system and determinesimplementation scheme of GNSS intermediate frequency signal generation based on theprinciples of satellite positioning. The paper developes the devise of GNSS intermediatefrequency signal source step by step, as the main line of the given implementation scheme.Second, it details the concrete implementation method of GNSS intermediatefrequency signal source, including the design of the interface, the generation of navigationmessage,reading the parameters of satellite from navigation message, the visibilityjudgment of the satellite.Then, it analyzes the error of the system model,and adds the pseudorange error tobaseband signal in order to make the signal source simulate real world more truly.Finally, the thesis proposes the software GNSS digital intermediate frequency signalsource which is used to generate and simulate the GNSS digital intermediate frequencysignals, and checks the accuracy of the generated intermediate frequency signal andanalyzes the results by the closed-loop test method with the software receiver.