【正文】 r the 100 ns, that is, 10 MHZ, the speed of data output to meet demand. Output data from the address by address accumulator, we address the accumulator after class to join the select level data, by scanning signals into digital data pulse switch channels, you can achieve after the latch or a single wave triggered after the show Mobile level. Sawtooth formation circuit: It was found that the programmable device EPM7128SLC8415 counting the internal structures of the circuit is very easy to have a burr so that the output sawtooth instability, thus we have a choice of hardware circuit count sawtooth. Sawtooth clock output from the circuit to provide data to ensure that the scanning signal and data signals simultaneously. Sawtooth dollars will be upon expiry of the binary pulses output after a delay Larger, gave the Zaxis analog oscilloscope, blanking flyback line. Trigger circuit: trigger level by the microcontroller through the D / A (MAX508) output, by parison with the input signal is pared to be trigger signal. The trigger signals to a microcontroller interrupt, the MCU after launch EPM7128 start collecting. Selection of the circuit here is relatively high gain, low noise, low drift YunOP37 posed by openloop. Its output by two diode limiter to be the standard TTL signal. Twotrace Oscillographic circuit: theoretically strict trace oscilloscope to double twoway signal sampling at the same time, then need two highspeed A / D, and its frontend circuit. But ordinary analog oscilloscope resolution is generally not high, thus has no significance to strictly require the two signals at the same time. Therefore, we used all the way acquisition circuit of the two alternate input signal sampling, data were collected will be stored in the memory of the oddeven address, respectively Oscillographic, the same can be done with high precision dualtrace Oscillographic, and to make the system Price increase. Minimum system circuit: the system to AT89C52 as the core. 20 keys from the keyboard posed by MM74C923 pleted its scan. Display System is the DCM162A, it is character LCD, there are two lines of 16, from 8bit characters in each line of five, because of its resolution is not high, difficult to display Chinese characters, so we use All English interface. In addition, the system also has 32 K of RAM (62256) and a 82 C55 port expansion as a backup. Part of the power system for the +5 V, +12 V and 12 V power supply three ways. Frequency Measurement modules: the use of SCM counter to measure the signal. Because the trigger pulse with the same input signal frequency, so just to trigger a pulse frequency can be measured. When the frequency of less than 5 Khz, the use of the method of measurement weeks, the measured signal to the gate for a period of time, the MCU to a machine cycle (1 us) for the benchmark time, that is, in its count cycle. When the input signal in the 5 K50K when measured by the frequency approach to the measured signal for the time benchmarks for the regular 1 S gate time, a timecount, that is, in frequency. Characters display module. The level of input in the Xaxis scanning signal, in Yaxis input field scanning signal, the Zaxis input signal brightness can be formed on the characters in the oscilloscope. The field scanning signals generated by the EPM7128 internal count. Zaxis data exist in the external ROM. Peak peak measurements: general AD (MAX197) on the importation of highspeed acquisition circuit to signal a longer time of sampling, get input signal to the maximum and minimum, and then their poor Value prior to passage by the decay times, you can get the input signal peaks peak. AUTOSCALE function: This feature automatically adjust to achieve the level of sensitivity and vertical sensitivity, so that waveform better be displayed. First, the system through the regular AD (MAX197) read as an input signal level trigger level so that the system is stable trigger. Then, call frequency measurement function, measured the frequency of input signal, because the level of sensitivity we will be divided into 20 us / div, , 2ms/div, 20ms/div, , in order to ensure that at least on the oscilloscope That a cycle of signal, so when the measured signal frequency f 5khz, with 20 us / div stall when the 500 hz， This system of measurement, the function and meet the targets were subject requirements. Completion of the functions are as follows: the input signal can be a single trigger, the trigger after the show that stability can not change with the input signal changes, the signal of a sampling of up to 2,048 sample points in a row could trigger mode of input signal sampling and realtime , And no significant wave distortion, the input signal is the exchange can also be a DC。 If the system of vertical sensitivity set at 1 v / div, the input signal for the peak5 v, grid displayed on the oscilloscope. Two indicators of measurement data are in line with demand. (2) the level of scanning speed test: When the input signal frequency set at 1 hz, scanning speed set at the level of s / div, displayed on the oscilloscope 5 grid。 ～177。 軟件的設計與實現： 虛擬數字示波器軟件設計采用了基于 C 語言的編程環(huán)境 LabWindows/CVI。在濾波處理 面板中包括以下功能：對實時采集的信號和自行產生的信號進行濾波處理 (包括單步濾波法、多步濾波法和傳統(tǒng)方法等 ). 源程序文件的生成： 當完成面板各個控件的設置后，就可以產生程序的代碼函數了。以下這段代碼實現數據采集功能，程序通過調用數據采集按鈕的回調函數 SHOU進行外部采集。 另外虛擬示波器相比傳統(tǒng)示波器具有價格低廉、功能豐富、可編程性以及顯示直觀等眾多優(yōu)勢。 ★數字濾波：采用數字 IIR 濾波器對信號進行濾波處理并實 時顯示，同時可以任意設置濾波器的最佳逼近函數類型、濾波器類型、階次、上下截止頻率等參數。 ★波形回顯：隨時將存儲的 LVM格式波形文件重新讀取然后顯示在 PC 機端。 由于在硬件上是以 PC機以及采集卡為基礎的，所以本示波器在采樣極限速率，帶寬，分辨力等參數上受到限制。 1. 移動光標至波形圖中的曲線圖例頂部。 4. 在 Plots 標簽內，從下拉菜單中選擇 Sawtooth。 7. 在 Name 文本框內， 刪除現在的標記，改變該條曲線的名字為 Scaled Sawtooth。例如，在 Scales 標簽內，禁用自動縮放功能。 用戶控制下的存儲數據： 完成下面的步驟，來 創(chuàng)建一個 VI 程序，當用戶點擊前面板的一個按鈕時， 把數據存入一個文件。 4. 右擊 Write L