Study On The Key Techniques Of Wireless Extensions For Instrumentation

The science and technology is rapidly developing every day, which pushes the test theory, instrumentation and Auto Test System(ATS) to progress. Today, the field remote Distributed Test System(DTS) has been widely applied in tests of bridge, railway, blasting, seismic exploration, and the like, among which the Wireless Scatter/Gather Distributed Testing System(WSG-DTS) is the best ATS for the above-mentioned. However, some weakness, such as low speed of data trasmission and low precision of T&S are associated with current WSG-DTS, so the study of key technology of Wireless extensions for Instrument which can be preferably appled in the field remote Distributed Test System is significant for the development of national economy. The following is the main content and production of the study:1. The instrument development tree is presented basing on the sum-up of all modern kinds of general instruments and test systems, which give directions for the study of new generation instrument.2. For the problems ocurr in the existing field remote DTS, such as low speed of data trasmission and the low precision of T&S, this paper advances an idea of Wireless extensions for Instrument(WXI) based on the development law of modern instumentation and the study of the modern instrument key technologies, Wireless Bus and T&S are the key stones.3. The research of IF digitalization communication sysytem theoretically indicates that the sample error is essentially a factor of the accumulative carrier error, which simplifies the algorithm of carrier synchronization. A joint algorithm of Pilot-symbol-aided frequency and timing synchronization with constant envelope and continuous phase modulation over the Ricean channel, is offered here, which tell us that the pilot-symbol timing offset is stochastic, and limited to Sub-nanosecond. The study of wireless extensions capability for instrument based on fixed OFDM in burst mode showes that the bandwidth of OFDM is greater than the current SG-DTS and Wireless Sensor Network(WSN), and the Wireless Bus can satisfy most DTS application requirements.4. This paper comes up with a WSG-DTS with modular WXI model and a WXI bus-bridge established on System On programmable Chip(SOPC) and Soft Defined Radio(SDR). To realize the multi-channel test, a strategy and design method of high speed SCSI drive real-time mass data storage is provided here. 5. The research of Wireless Bus transmmition delay finds that the dithering of the delay is scaled within sub-nanosecond. Standing on that, this paper logically illuminates the WXI T&S Protocol(WTSP) based on the modification of LXI synchronization Protocol. Then the methods for trigerring synchronization with maximum transmission delay or minmum transmission delay and sample clocks synchronizing are introduced. The algorithm of sample clocks synchronization can be deduced from GPS PPS(Pulses Per Second) and DDS(Direct Digital synthesis), or Local Oscillator(LO) and WTSP jointly. Lastly the WSG-DTS system structure with WXI is discussed, and one embedded WTSP engine is presented in the end.