【正文】 dge. When changing the position of the waveform, change the coordinate of the zero mark at the same time. So the zero mark will move with the waveform. In addition, set the mark button control invisible outside the top and bottom edges, that the effect can be truer. As seen in . E. Other functions What discussed above are the 3 basic functions in a virtual oscillograph. For other functions such as trig mode, couple mode, cursor, data storage, replay and print etc. are not discussed in this paper. According to actual needs, all the functions mentioned above can be achieved well through making full use of the property node in LabVIEW. III. CALCULATION OF FREQUENCY AND PERIOD Period and frequency are key parameters to a periodic signal. Traditional measurement is to count the standard signal during the gate pulse duration in hardware so as to calculate the period of the measured signal. But there areusually no counters on hardware to use for a virtual oscillograph based on PC. It must be measured through software. However, the significance in a virtual oscillograph is that it can conveniently analyze the data collected by board cards, and then get the waveform39。s capacity is N, which is the number of data points calculated via Eq. (1). 附 錄 4 Suppose the number of data points read from board card every time is a fixed value m, which is the number of data points to be read at the proper time base. The whole procedure is made up of two parts. First, set the whole array NULL. At the beginning of the display procedure, the array is not full. So put the new m data points into the end of the array (Enqueue), and then display the whole array value in the graph control. A continuously moving waveform should be showed in the screen. Second, when the array is full, get rid of first m elements of the array。 and after adjusting, replace the related array element with the new value. And then the amplitude value change function is finished. C. Time Base Adjustment Time base adjusting is one of the basic functions in oscillograph. The time base adjusting knob39。t satisfy most of operators because it is different from the tradition oscillograph in operation. To solve these problems, this paper brings forward 附 錄 2 some ways. In the real time waveform display, we redevelop the waveform operation and introduce some related software arithmetic. It introduces the exploiting thinking of adjusting dynamic time base and put forward two concepts: the FIFO process and EM process. In addition, it introduces a successful gatevoltage measure way in the measurement of the period and frequency, and based on which, the paper puts forward the application in the closeloop lockphase System. II. RESEARCH ON THE MULTICENTER DIGITAL OSCILLOGRAPH39。 Development of Virtual Oscillograph Based on LabVIEW Abstract: This paper introduces the design process of a virtual oscillograph based on LabVIEW. Mainly analyzes the amplitude value and time base adjusting methods during the realtime display. At the same time, it simply introduces the basic thought when measuring the period and frequency of the waveform gate voltage method and its application. At the end of this paper, bining the parameter measurement and waveform display of the virtual oscillograph with the modern motor closeloop lockphase speed control, it analyzes the parameter measurement39。s effect in PID control. Keywords: Virtual Oscillograph。S SOFTWARE ARITHMETIC The virtual oscillograph introduced by this paper is mainly used in laboratory for the measurement and storage of various analog signals. The main functions are: data acquisition, waveform display, parameter measurement, waveform storage and replay etc. It has 64 analog signal input channels and can take 8 signal observations at the same time with the choice of switch matrix. According to the requirement, we use the NI6133 Daq card for the data acquisition. The block diagram of virtual oscillograph is shown in Fig. 1: [6] Now we will introduce the soft arithmetic to the basic functions of virtual oscillograph. A. Characteristics of Graph Control In LabVIEW, there are three controls for waveform displaying: Graph, Chat and xy graph. Every control has its own advantages. This paper takes Graph control for example to discuss the soft arithmetic to the basic function of virtual oscillograph. Graph oscillograph displays all waveform data input in the screen at a time. Every time when the waveform data are input, the screen will be freshed. [7] Using its own operation tools, you can move, zoom the waveform or use the cursors to measure the parameters. But it could not work well on dynamic waveform. So it39。s value shows the time of every one grid of Xaxis in the screen which is the nodus during the oscillograph design procedure. 1) Basic Clew According to the characteristics of the Graph control, it displays all the data input at a time. So distribute the X axis into 10 grids and make every grid39。 move the rest Nm elements forward the beginning of the array。s eigenvalue. So the basic clew to measure the waveform39。s error coefficient is a. The measured signal39?！?T0 )， and the time the k signal periods pass is t+kT+(αkT177。, so there is: 附 錄 7 What discussed above is the period and frequency measurement in the sampling procedure, putting forward the measurement precision theory. But to the amplitude, rise time or spectrum analyze etc. are not discussed in this paper. Using the data group collected, the user can develop other better measurements. In LabVIEW, there is plenty of measuring VIs, which can measure the parameter exactly. [10] Combining the control procedure with virtual oscillograph can achieve better effect. Next, take DC motor39。an China, 2020 [6] , and , Design and implementation of virtual instrument based on LabVIEW 7i, In