Study On The High Dynamic And Whole Digital Intermediate Frequency Direct Sequence Spread Spectrum Receiver System

With the people's increasing needs of wireless communication equipment, wireless frequency band becomes more congested and all kinds of interference also strengthen. The spread spectrum communication has been a very important communication mode and it's application has been found in many fields. It is very necessary to research the spread spectrum communication, because it has many merits, such as anti-jamming, secret and low cost. On conditions of the current technology,the thesis puts forward a new high dynamic and whole digital spread spectrum receiver which is based on the high density programmable logic devices. Firstly, the principle and realization of the step acquisition and delay locked loop are discussed. In view of the actual need, we bring forth the solution of whole digital spread spectrum system, which comprises transmitter and receiver.Secondly, we prove the self-relation function and correlation function of pseudo noise code sequence and obtain the shift register generating circuit from it's generating function. Then,we complete the intermediate frequency digital acquisition and tracking circuits according to the band pass sample theory, digital signal processing theory, multiple rate signal processing theory and digital filter theory. The output components of the de-spreading correlator are analyzed and the expressions for the PF and PD of the step acquisition are given under the condition of additive white gauss noise.Finally, the main parts of the system circuit are discussed. Some experiment circuits and results are given and analyzed. It is seen that the spread spectrum receiver has stable performance, small size, and can be easily produced and flexibly updated.It is believed that with the rapid development of the communication technology, the applications of the digital spread spectrum receiver will be extensive, especially in uniform telemetry and telecontrol systems.