It Is Applied To The Research Of Baseband Processing Of The Calibration Projectile Signal Transmitter

In recent years,higher standards have been put forward for the hit accuracy of a large number of uncontrolled projectiles in China.It's quite necessary to acquire the exact falling position of the projectile to adjust the firing angle of the next projectile.So the measurement of the projectile falling point is of great importance.In our lab,the method of acquiring the current time position of the projectile is first adding satellite navigation and positioning device inside the projectile.Then,we will transmit the position back to the emplacement through a data transmitter and adjust the gun muzzle to improve the hit accuracy of the next projectile.With this method,the timeliness,accuracy,antiinterference performance and concealment can be guaranteed.To solve the data transmitting problem,this thesis conducts in-depth study on the baseband information processing of data transmitter.The main work is as follows:Firstly,according to the characteristics of data transmitter of the projectile including lowpower consumption,long-distance transmission,diffraction and multi-projectile information reception,I design the structure of the SSC(Spread Spectrum Communication).Having compared and analyzed the merits and demerits of four kinds of SSC,I select the direct sequence SSC technology and establish the related model.Then,this thesis will explore the the generation method of the spreading sequence codes and deduce the spreading sequence codes this thesis needs through selecting and optimizing of primitive polynomial and balancing Gold codes,In order to meet the requirements of diffraction,I choose the link calculation method to find out the maxium value of the diffraction loss under the condition that the transmitting power is 5W.Then diffraction height can be calculated based on the diffraction model.Besides,the spread spectrum and de-spread process of the SSC are simulated through using MATLAB to compare the results from the hardware platform.Thirdly,according to the requirements of the above system,the data transmitter function module is achieved on the FPGA SPARTAN6 development platform which include serial port data input,the generation of spreading codes,carrier generation,spread spectrum modulation,carrier modulation,DA conversion and so on.Using ModelSim to verify the timing verification of the above functional modules and testing the board level testing on the hardware development platform,we can find the the new designed transmitter can complete the predetermined functions correctly and has good effect.