Li Nuo

Realization of automatic test system of crystal oscillator inside the universal counter

This thesis introduces the working principle of the universal counter frequency and period measurement and expounds the important function of the crystal oscillator inside universal counter. This paper designs a system which uses the technologies of time-sharing control and video capture to realize the automatic test of multiple crystal oscillators inside the universal counters at the same time.

Control of stepper motor based on VC++ and PCI-1240

With the platform of industrial PC and VC++ software, this paper researches on how to use PCI-1240 motor control card to achieve the control of stepper motor by sending control signals to stepper motor controller. A control system to realize the accurate control of the motion of stepper motor is designed. It is proved that this method is accurate, reliable, easy to operate, and practical in industry.

Calibration device for multi-parameter simulator

Multi-parameter simulator is famous because of its more parameters in use and cumbersome steps in calibration. This paper introduces a device which makes the calibration more convenient without oscilloscope, programmable amplifier, programmable filter and stabilized voltage supply. With this device, the key parameters of simulator can be traced back to National Standard. The paper also gives the feasibility analysis of Levkov method which is widely used in electrocardiograph and presents the improving method against its reduction in QRS-wave of ECG.