Design And Implementation Of A Short Wave Receiver RF Front-end

Short wave communication technology plays an important role in the military, navigation,broadcast and emergency communication. With the development of signal processing technologyand electronic devices，the short-wave receiver is becoming more and more automated, intelligentand digital. Therefore, a special short wave receiver is studied in this thesis.On demand of an actual project, some main parameters relevant to the short-wave receiver aredescribed, including the noise figure，third order intercept point，sensitivity and1dB compressionpoint. Feasibility analysis of the receiver system as well as simulation of gain and noise budge byADS software is also presented. In the hardware implementation of the receiver, thesuper-heterodyne receiver with single conversion is selected. Follow the design schematic, the DDSis adopted to obtain local oscillator signal (LO) with high precision and stability. A large dynamicrange of the receiver system can be obtained by using two cascaded automatic gain control (AGC)circuit units.Finally, the schematic circuit diagram and the printed circuit broad for the receiver system aredesigned and tested. The measured results show that the AGC circuit has a wide adjusted range ofmore than60dB. The power range of the DDS output signal is from10dBm to15dBm; the Phasenoise of the DDS is less than-90dBc/Hz. The feasibility and practicality of the design system isverified through measured results of the hardware object.