The Design And Implementation Of Intelligent Measuring Device For Isolation Of Multi-channel Signals

In the fields of aerospace telemetry, that monitoring the measurement signal can helpworkers master the environment data and working condition of the vehicle.Based on thereal-time reliable data, we can make knowledge of the overall performance and analyze thefault of aircraft. Both of them can make further improvement. How to collect and store themeasured signal parameters is particularly important. The design requests to acquire andstore the multi-channel analog signals and PCM serial data signals. Among themulti-channel signals, they should be isolated and non-interference.The paper adopts the ideas of "all the signal isolation" to project, mainly includingsignal isolation and power supply isolation. For ground self-inspection test, the tester wouldoutput six-channel analog variable voltage signals. Using the linear optical coupling chip,we constitute optical coupling isolation circuit to isolate the analog signal. Among them, allanalog voltage signal and PCM data signal would be isolated. By the measuring device, theanalog signal is isolated and though the A/D transformation and sampling, it can be directlystored within the memory of measuring device. The PCM code data can not be affected bythe parameters storage. For the power supply module, we take intelligent choice betweentelemetry system supply and storage device selfsupply. In order to avoid power outagewhich is by the lead of the instant landing of aircraft and can’t work anymore, besides thesecondary power supply from the telemetry system, we put a more power supply module inthe measuring device. The protect signal acts as start signal of the beginning of powersupply of solid-state memory. It is used to ensure completely collect of multi-channelisolation signal at the moment of aircraft landing, which make the measuring device realizethe whole intelligent power supply.For gathering the landing voltage parameters and PCM code data, we proposed todesign a new collection and storage measuring device based on linear optical coupling HCNR201and A/D analog-to-digital converter ADS8365with power supply isolation. It isused to realize the collection and receiving of all analog voltage signal and PCM digitalsignal, then stores them in the FLASH. Here we take optical coupling isolation chipHCNR201to constitute optical coupling circuit to isolate all0~5v analog voltage signal.By Xilinx’s XC3S200AN, it controls ADS8365analog-to-digital converter. The RS-422asynchronous serial interface circuit receives the PCM digital stream signal. After analoghybrid encoding of analog data and digital data, put them into FLASH. The article pay moreattention to expound the collection and storage technology of intelligent measuring device,whose system hardware circuit and FPGA logic code in particular. The analog waveformfrom testing is stable and the stored data is integrated and reliable.We can take conclusion of that the system can successfully isolate and collect themulti-channel signal, which meets the design requirements.