Research On Programme-Controlled Signal Source Based On DDS Technology

A programme-controlled signal source based on DDS technology has been developed. The signal source can be used in some dynamic measurement systems, such as piezoelectric acceleration calibration system, ultrasonic ranging system, thereby provides a basic for establishing a high-efficient computer-based automatic measurement platform. Comparing with the traditional manual signal sources, the programme-controlled signal source greatly improves the efficiency and reduces human intervention, and ensures measurement accuracy.DDS technology is the third generation of the frequency synthesis technology. DDS technology has some prominent merits, such as quick frequency conversion rate, high resolution, continual phase, and so on, so that has found widespread applications. DDS Chip AD9850 has precise output frequency, small frequency interval, and high signal to noise ratio. The signal source designed in this paper is based on DDS technology, and is realized by using the DDS chip AD9850 controlled by singlechip AT89S51. The principle of the signal source, which consists of five basic modules, i.e. the singlechip controller with interface circuit, the chip AD9850, filter, scope controller, and wave selector, is described in detail. The singlechip procedure is compiled with the MCS-51 assembly language. The paper has also designed the Printed Circuit Board for the signal source.Graphical programming environment LabVIEW is a famous virtual development platform. It abandons the complexity of the traditional developing instrument, while providing the formidable function and guaranteeing the flexibility. This paper regards LabVIEW software as the platform, designs the programme-controlled interface for this signal source. The central function of the interface is to realize the serial communication between computer and singlechip. As long as the user inputs the data to the interface, the LabVIEW procedure transforms these data into the binary form, then transmits these information with the character string form by using the computer serial port. Then singlechip AT89S51 receives the data, processes the data, and turns it into the control word which AD9850 and other modules can identify. After the process...