The Research Of Some Detection Questions Of LAMOST Based On ZigBee

For observing thousands of celestial bodies simultaneously, 4,000 nodes with an alveolate distribution on the focal plate of 1.75m in diameter are used in LAMOST(Large Sky Area Multi-Object Fiber Spectroscopy Telescope). The pre-project of LAMOST is traditional control way of wire drive. The project is that one FPGA controls 16 step motors and 16 zeros. The mature technology is adopted in the project, but the cable is too long, because the control system is far from the focal plate. For optimizing the control system, the item team decides to use the wireless technology of ZigBee to control 4000 nodes by comparing existent wireless technology.By synthetical consideration, the item team selects the ZigBee product of Freescale to do pre-research.The performance of ZigBee with high density of units is not described by ZigBee Alliance or Freescale, so an experiment system is designed to detect the performance of ZigBee so as to know the communication performance of ZigBee with high density.The system consists of the communication experiment of a channel and the communication experiment of four channels. Error correction or checkout is not used in the system so that we can detect the basic characteristic of ZigBee system with high density of units. Bit error that is getted by data comparability is used in order to describe the communication performance directly. Bit error of communication in a single channel or four channels is detected by comparing the sending data with the receiving data.As mentioned before, the number of nodes used in LAMOST is 4,000 and it is large. The disadvantage factor may exist because of the manufacture of circuit board and the jointing of devices. For getting the driving performance of electric machine and the communication performance of 4,000 nodes that are used in LAMOST, we design the detection experiment. The experiment consists of two parts: the ageing test of driving circuit board, the carrier wave test of driving circuit board and the operation test of returning to zeros.