Research On The Method Of Simulating Navigation Signals Accurately Based On BOC Modulation

With the rapid development of global navigation satellite system which is playing an increasingly important role in the national economy, many countries have begun to develop their own satellite navigation system. But along with the increase of satellite navigation system, the compatibility and interoperability between the various systems is a problem that should be solved urgently, BOC(Binary Offset Carrier) modulation gives a good solution to the problem. The precise simulation of the satellite navigation signals based on BOC modulation has also become the foundation of the development of analog source, because highly precise navigation signals simulation is important to the verification of signal system scheme, to the research, production and testing of user equipment. Taking the research of BD-2 navigation signal analog source as the background, the precise generation of navigation signals is researched in the paper. Main research results are showed as follows.(1).The methods of precise time delay are analysised and simulated deeply in this paper. The producing scheme of the precise time delay which is based on digital delay filter or based on look-up table is the focus of the paper. The simulation results show that the two sets of program all achieve delay accuracy of 0.02ns.(2).The satellite orbit that impacts the generation of navigation signals is modeled. And the paper also models and simulates the multi-path effects with combining BOC modulation and the methods of precise delay generation.The results show that the BOC modulation can effectively reduce the multipath error.(3).The signal test system is constructed, which is based on CPCI bus. The system tests the generated signals in the way of data acquisition and playback. Firstly the baseband data of navigation signals is produced in the way of software, and then let the baseband data go through high speed DA output card which will outputs IF analog signals. The data acquisition and playback system then transforms anlog signals into digtal signals which are stored in the disk array. Finally, the data in the disk array is analysised in Matlab.The testing results show that the spectrum of the navigation signals agree with the theory analysis.In a word,the paper initially implements the simulation of navigation signal based on BOC modulation and also constructes the signal testing system. This will promote the manufacture of our country's multi-institutional analog source with high performance and the development of satellite navigation industry.