| Now in the measurement field, it is very common to measure the floating signals with several different reference points, such as detecting an uninterruptible power supply, the diagnosis of motor drivers, industrial control equipment and power system, even measuring an amplifier and other analog circuits. When we measure the signal by the traditional Digital Storage Oscilloscope (DSO), the grounds between channels in the DSO are connected internally so that it will make danger in measuring the floating signals such as short-circuit or even fire in the high-power electrical devices, which will not only destroy the equipment, but also make persons’safety not be guaranteed.This article presents a Digital Storage Oscilloscope Channel Isolation System, which contains the signal isolation of the analog channel in DSO, the control isolation and power isolation hardware design. This system makes the channels themselves, channel and acquisition system motherboard isoTate from each other,Therefore,the danger of short-circuit and others will not happen while we have the measurement in floating voltage.In the research design process, the isolation of the analog signal transmission is the key part in the whole isolation system design. This article presents an application circuit by using the optical coupler, isolated transformers and other devices formed in the back-end of the analog channel in DSO. Meanwhile, the motherboard controls the various modules of the analog channels by an isolation circuit designed by this article. And a channel power supply isolation module is presented in the article. The signal isolation module, control isolation module and the isolated power module constitute the DSO channel isolation system, which has the signal bandwidth from DC-100MHz and meets the indicators of design requirements.Besides the whole isolation system design, the article presents a USB isolation module of the human-computer interaction interface for the DSO and gives the hardware design, which not only ensures the transfer rate between DSO and computer, but also isolates the signal between the two devices. |
