The System Design Of Hand-held Digital Oscilloscope Tablets

It’s about more than sixty years since the first appearance of analog oscilloscope. Since1980s, digital oscilloscope has been fully replaced analog oscilloscope due to its unique outstanding features which can’t be found in a variety of analog oscilloscopes. In recent years, lots of digital oscilloscopes companies come out rapidly. They have made a considerable progress in real-time sampling and storage capability. However, the current digital oscilloscope also has some disadvantages, such as large size, heavy weight, complex operation, narrow application field and so on. Therefore, it’s quite necessary to develop a small, light and easy to carry color digital oscilloscopes. This paper studies the design of hand-held oscilloscope data collection system in real-time and random sampling mode, the implement of color LCD display control circuit based on BUS control,waveform display software and other related issues.This paper mainly includes:1. Signal input channel designs. The input channel is the basic circuit, which is responsible for adjusting the input signal. It’s including coupling and attenuation circuit, impedance matching circuit, programmable amplifier circuit, the DC bias circuit, the trigger circuit, A/D conversion circuit and the power supply circuit. In this paper, an integrated operational amplifier and programmable amplifier is used to construct this design, in order to simplify the hardware circuit while ensuring the input bandwidth, and easy to achieve precise control.2. Data acquisition system、LCD、touch module design. Data acquisition system is the core part of the hand-held digital oscilloscope, which is the most important difference between analog oscilloscopes. This paper presents a hand-held instrument based on a single FPGA structure with logic circuits, and Nios soft core embedded in a single chip. Based on this structure, with the real-time sample technology,3. waveform acquisition, storage software design. High speed A/D waveform acquisition is a high real-time, sudden large amount of data, the design needs to use the Verilog design of HDL parallel software description of sampling, storage process, designed with a specific trigger conditions25MHz sampling rate of digital acquisition system, and both hardware frequency meter function.4. Waveform display software design. Describes a various ways of collected data re-construction on LCD, including SCAN mode, STOP mode, and waveform reproduction under real-time sampling mode and so on.