π/4-QPSK Figure Modulate And Demodulation Of The Receiver

With the development of microelectric technique,signal processing technology and computer technology,communication technology has changed from Analog communication to the digital.Digital communication has got the acknowledging generally of the society with its one's own outstanding quality,has gained the extensive market,and has occupied the leading position of the communication field rapidly.On the basis of the mobile communication system of satellite communication and application in personal communication system being more and more extensive,how to accurate receiving and demodulation on the satellite signal,respond to the request that work pattern happens suddenly,become a new subject that we face.On the other hand, because of the drive of Internet,like other communication technology,satellite communication is being turned to the overall demand for data communication.Concrete to say ripe based on C wave band and Ku wave band technology VSAT system constant gradual progress meet Internet request of business already on one hand,and become an important component of global Internet network,adopt higher Ka frequency band technology on the other hand,can really realize the broadband satellite communication system of personal communication,especially low one group of systems of orbiter is being developed,tested and in construction,what this text discuss modulate the demodulation machine Ka wave band tactics digital satellite communication the whole figure of technical research.A lot of new concepts and new thoughts that have appeared in the last few years,such as many aerials of speed of wave,intellectual aerial,software radio,packet wave switching at the star,the star processing,satellite communication of VSAT,mobile satellite communication,intelligent network,the new technology of power / frequency spectrum utilized and IP QoS,MAC layer,assembles on story and uses effective agreement treatment technology of one layer of respects,etc.to combine closely with one's own characteristic of satellite communication,have produced a series of peculiar new technologies.These new concepts,the realization of new thought and new technology,have promoted the process that satellite communication technology transforms into satellite communication system of new generation in an all-round way, fast.Above-mentioned communication system a key technology involved to want that the whole digital receive technology.Research work of this text is researched and developed under Ka wave bandπ/4-QPSK's figure modulate the receiver,content its involve channel compiled code,is it deal with,turn into speed not to deal with to interweave and figure modulate demodulation,this text main researchπ/ 4- QPSK digital demodulation is it resume algorithm with signal carrier to move ahead simultaneously regularly,and the modulation demodulation under ADSP21161 development environment is realized. During the thesis,through reading relevant documents,study forefathers' maturity method,combine the existing digital signal processor level,according to the communication condition in the actual project,design suitable digitized demodulation scheme,analyze and combine computer emulation not to prove feasibility of plan of design through mathematics.Its groundwork is as follows:1.Consult a large number of references,analyze many kinds of demodulation algorithm,select heavy average power algorithm solve the problem that move ahead simultaneously regularly most,and carry on the emulation of algorithms under the environment of MATLAB,verify the feasibility and dependability of the algorithm.2.Consider that leans towards influence that exists frequently,through consulting a large number of references,lean towards and measure the voltage production circuit frequently in the tradition --On balancing and paying the relevant device and dual wave filters and leaning towards the foundation of the detection frequently,have studied the digital signal carrier and leant towards the algorithm of observing frequently,has verified the exactness and feasibility of the algorithm in emulation.3.Timing adopt heavy average power timing synchronous algorithm most in step, estimation that lean towards frequently adopt the whole figure simply the observing device is estimated frequently,implement to Calman and strain waves to symbol timing and estimation that the signal carrier lean towards frequently,summarize the system structure of the digital demodulation algorithm,has put forward the systematic plan of design of hardware briefly.4.Assess board finish heavy average power timing synchronous DSP software design of algorithm most in ADSP-21161N,through demodulationπ/ 4- QPSK signal prove correct competent and practicability of algorithm.The digital demodulation algorithm was dealt with the algorithm and formed by a series of digital signals.In order to make it convenient for digital signal implementation to deal with algorithm,digital demodulation system compared with traditional simulation method structure that algorithm realize have heavy change very,especially already been synchronously and systematically totally different from the traditional synchronous systematic structure,here consult signal cartier and sample clock frequency and phase place of signal change,so the phase locking can't be used to surround technology directly.Draw one digital demodulation plan of design of algorithm,timing among them adopt heavy average power timing synchronous algorithm most in step,to adopt the estimating device realize simply frequently simply frequently signal carrier.When prolong not estimating and not frequently simply it estimate not adopting there aren't Kalman.