C-band Frequency Conversion System Is Developed

The subject derives from the project of "C-band Down Converter" , which is contented with the satellite testing and controlling system. It deals with the signal from the satellite. The converter mainly accomplishes changing the C-band RF to intermediate frequency 70MHz, amplifying and gaining .The thesis includes R&D of local oscillator and group-delay equalizer.The thesis overall views the historical development future trend, introduces the theories, applications and characteristics. Based on that and the actual request, the thesis focuses on two ways of frequency synthesis: Phase-Loop Locked and Phase-Loop Locked + Direct Digital Synthesis. Then it introduces the concepts of group-delay and all-pass network, analyzes the theory of equalizing the group-delay of filter by all-pass network, simulates the design and sums up a perfect designing and debugging precept.In this system two oscillator are used for mixing. PLL for high local oscillator and DDS+PLL for low local oscillator. By making full use of favourable narrow-band tracing filter character of PLL and by combining the merits of DDS such as super fine frequency resolution, high frequency accuracy, very fast frequency hoping with it, the PLL/PLL+DDS frequency synthesizer presents wide band high quality source and super small frequency hoping step. While the all-pass network for equalizing improves the precision of signal transmission. At last the circuitry realization ?some test data and trouble shooting are presented. The measure results are much better than the product of the other institute.