Design Of The Frequency Phase Generator In The Intelligent Test System

The design of the high-precision frequency generator in the intelligent test system is analyzed in this thesis. A frequency/phase-tunable and high-precision signal source is needed in the intelligent test system. The user inputs signal's frequency and its phase. Through serial port on PC, the pre-programmed controlled words are sent into AT89C2051 microcomputer to process, then into AD9850. Finally, the AD9850 generates a spectrally pure, frequency/phase-programmable, analog output sine wave. The paper describes mainly a method to realize the communication between PC and AT89C2051 microprocessor and AD9850 using Visual Basic and assemble language, including the circuits of hardware, the flow chart of software.The AD9850 is a highly integrated device that uses advanced DDS technology coupled with an internal high speed, high performance, D/A converter and comparator, to form a complete dialtally programmable trequency synthesizer and clock generator function. AD9850 applies widely in recent years because its price is not expensive and its performance is super .The frequency tuning control, and phase modulation words are loaded into AD9850 via a parallel byte or serialloading format. Most of application of AD9850 use parallel loading format because parallel loading format is simpler than another. But parallel port resource is scarce .So the serial loading format is adapted in this design.