Design And Research Of Isolate Four-channel Digital Store Oscilloscope

Compared with the traditional analogue oscilloscope, digital storage oscilloscope(DSO) has many advantages, such as single signal capture, data storage, self testing, etc. There were more and more applications in the engineering practice. In practical projects, we often need to measure some signals which are not allowed to have common ground. Sometimes,using traditional oscilloscope may cause the experiment's failure, even damage experiment devices. Isolated multi-channels oscilloscope can solve this problem by isolating each channel.This paper studied data acquisition algorithm, used ARM and CPLD system structure, designed the four channels digital storage oscilloscope with isolation function.This paper introduced the sampling way of DSO and studied the interpolation algorithm in real-time sampling. It used the isolated op-amp to isolate channel and high speed A/D data acquisition. It designed the signal front circuit, trigger circuit, data acquisition control, LCD display driver. Using ARM as the master of whole control system and do all kinds of operations and algorithm. Using CPLD manage the external circuit and display driver.In the hardware, attenuation network choose different pressure resistance to attenuate signals by relays. CIM1100 is a MHz level broadband isolated amplifier, each of four channels using it to realize isolating between the channels. The ADC choose a high speed chip MAX1448. This design adopted LCD as screen displayer, designed the display driver whice produces various timings and formulates corresponding control commands.In the software, using modular design, acquisition and display module subdivided, relatively independent of each module to facilitate debugging and upgrades. Studied the real-time sampling of the linear interpolation and the sine interpolation algorithm. With this specific design of this system, software realized this two kinds of algorithms and make them modular.The test showed that this design can successful measured wave and realize isolating effect, satisfied the requirement of practical application.