| Satellite navigation and positioning system plays a great part in national economicconstruction, military and defense field. With the development of navigation andpositioning technology, network constructing of the “Compass-II” satellite navigationsystem is developing gradually. In order to meet the demands of practical requirementsof satellite navigation, a RF (radio frequency) front-end for “Compass-II” satellitenavigation system is designed and realized in this paper.Firstly, the development situation of receivers and satellite navigation industry athome and abroad is introduced; next, super-heterodyne structure is preferred byanalyzing and comparing different topological structures of receiver’s RF front-end,after that, appropriate chips are selected based on performance indicators of the system,then thorough and overall system-level simulation model is established by ADSsoftware, which verifies the feasibility of this plan; after providing the indicators of eachmodule, the LNA is designed by ADS software and the mixer, AGC, PLL is designedaccording to the datasheets of these selected chips; Finally, all modules joint togetherwith necessary match and filtering circuits, results are recorded and analyzed afterperformance test.After debugging and improvement, the measured data of theses hardware objectindicates that VSWR of each port is less than2.0; the total gain of the link circuit is120dB with60dB AGC range; the noise of the receiver is less than1.5dB; and thefrequency15491.110MHz, the frequency stability-78.89dBc/Hz@10KHz LO signalsare generated by PLL. With the analysis of measured results, the testing data meets thespecification requirements basically. |
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