The microelectromechanical system (MEMS) gyroscope has low measurement accuracy and large output noise; the useful signal is often submerged in the noise. A new denoising method of interval empirical mode decomposition (IEMD) is proposed. Firstly, the traditional EMD algorithm is used to decompose the signal into a finite number of intrinsic mode functions (IMFs). Based on the Bhattacharyya distance analysis and the characteristics of the autocorrelation function, a screening mechanism is proposed to divide IMFs into three categories: noise IMFs, mixed IMFs, and signal IMFs. Then, the traditional modelling filtering method is used to filter the mixed IMFs. Finally, the mixed IMFs after modelling and filtering and signal IMFs are reconstructed to obtain the denoised signal. In the experimental analysis, the static denoising experiment of the turntable, the Allan variance analysis, dynamic denoising experiment, and vehicle experiment are set up in this paper, which fully proves that the method has obvious advantages in denoising and greatly improves the quality of signal and the accuracy of the inertial navigation system solution.
All the advantages of AON are fully utilized to satisfy the need of reliabilities, large-capacity and high-speed communication of high-speed railway transport system. Introduction In the system of orbit traffic, due to the high requirements of real-time quality and structural reliability of the system, AON is applied for the realization of interconnection and intercommunication of the system and improvement of the rate, immunity and wide-area quality of system communication. AON is introduced to the orbit traffic system in this paper. Regional monitoring-control and expandability of system is realized via designing the regional all-optical networks topology structure and researching the access and exit of net node. 1. System topologies AON, as a switching network, has a variety of topology structure[1]: tree shape, toroidal or bus topology. For the improvement of fault-tolerance, AON can also adopt dual-ring and soxju structure, and may make partial redundancy in the important paths of structure. (Reference to graph 1). In this paper, we mainly discuss the tree shape in allusion to the feature of orbit traffic system, the method and mechanism brought forward can also be applied in other topology structures Fig.1 AON topologies This network structure is composed of OLE ( Optical Line Terminal) of the main monitoring-control node point, optical splitter (OS)and ONUs (Optical Network Units) It only has some passive equipment, such as optical fiber and couplers in the transmission path of signals. OLT is on one end of the main monitoring-control node point. ONUs are on each terminal node and connected by optical networks. On the downlink direction, OLT delivers data packet and controlling information to each node by the way of broadcasting using shunt circuit couplers of I :N. Each ONU extracts the specific data packet on the basis of medium access control (MAC)[2].On the uplink direction, the data which are sent from each node point has no choice but to transmit to main monitoring-control node point. Because the Ethernet data packets which are sent by each node point share the fiber, for the purpose of preventing data packet from impacting each other and assigning bandwidths fairly, OLT adopts granting transmission windows(GTW) whose length is alterable to assign the sending time-interval of each node point. One node point is only allowed to transmit data in its GTW which is assigned for it. Node points use Report Message of GTW to apply for bandwidths. ONU of each node point caches data received by this node point and sends out the data which are cached at once when its GTW is coming.
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