Design And Implementation Of The GPS/compass Dual-mode Receiver Front-end

The end product of satellite navigation and positioning used GPS technology isabove95%in China. It is almost entirely depended on foreign, so it has a huge potentialdanger. it is more danger for military applications. At present, the Compass satellitenavigation and positioning system is still in development and exposed some problemsinevitably in application. The important thing is that the dual-model receiver can receiveGPS satellite signals and Compass satellite signals. Not only can the dual-modelreceiver can improve the positioning accuracy, but also the more importantly, when theGPS system fails, the Compass system still can work. It can be avoided in a passivesituation in war. And it is extremely important significance for China to study theGPS/Compass dual-mode receiver.The research direction of this paper is the GPS/Compass dual-mode receiver. Asstudied the specs of receiver, decided to use super heterodyne structure to achieve it. Inorder to anti-interference, there are four channels. In order to have a betteranti-interference ability, we should consider it’s coherency of amplitude and phasebetween the four channels. The module of LO used PLL to achieve. We should considerphase noise and spur-rejection.First of all, introduced the principle of GPS, and compared it with Compassnavigation and positioning system in briefly, and then combined with the requirements,analyzed the advantages and disadvantages of the super heterodyne structure receiverthat used in this paper. The thesis is consists of three parts. The first part is the designand implement of the channel of receiver. Introduced specs used in detail, how to selectthe device and achieve the circuits. The second part is the design and implement of themodel of LO, Introduced the module of local oscillator used CPPLL in briefly, analyzedits principle, the specs used, how to select the device and achieve the circuits. The lastpart is measured the circuit and debugged with digital signal processing board, bymeasured the circuit, the result is: noise figure is2.5dB, gain is57dB, sensitivity is-133dBm, the output P1dBis5dBm, the coherence of amplitude exceed0.5dB, thecoherence of phase exceed5°, the output power of the module of LO is6.5dBm, the spur-rejection is exceed-65dBc, phase noise is-80dBc/Hz@1KHz. The measurementresult showed that it’s satisfied the requirement and the principle prototype thatdesigned and manufactured in this paper is success.Finally, make a summary and put forward some suggestions for improvement.The difficulty is that how to determine the solution of the dual-mode receiver, howto select the device to achieve the solution, and adjust the coherency of amplitude andphase between the four channels.