Showing papers on "Sensor node published in 1991"
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18 Mar 1991
TL;DR: In this article, a frequency-hopping packet communication system without a master clock or master control unit is based on use of a receiver's frequency hopping timing and identification to control communication.
Abstract: A frequency-hopping packet communication system without a master clock or master control unit is based on use of a receiver's frequency hopping timing and identification to control communication. A frequency-hopping band plan, involving the number of channels and the pseudo-random pattern of frequency change and nominal timing of changes, is universally known to each node in the network. Frequency-hopping is implemented by the division of communication slots and the accumulation of slots into epochs, wherein each epoch equals the total number of available slots (number of channels times the number of time frames per channel). A transmitting node tracks the preestablished frequency-hopping pattern for its target receiver based on previously-acquired information. The transmission node identifies a receiver node and a current frequency channel of such receiver node. The transmission node then checks the frequency channel to determine if available (e.g., not in use and within an acceptable noise margin). If unavailable, the transmission node delays transmission to the identified node to a later slot. During the delay, the transmission node identifies another receiver node and a corresponding current frequency channel. The steps of identifying a receiver node and checking the corresponding current frequency channel are repeated until a node having an available frequency channel is identified. The transmission node then sends a packet to the selected receiver node at a frequency and for a duration defined according to the current slot. Such transmission node tracks the changing frequency of the selected receiver node to maintain frequency synchronization.
136 citations
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03 Nov 1991TL;DR: The authors describe RCD (region of constant depth) tracking and for this develop a monopulse sonar arrangement with which they implement real-time autonomous tracking by a single sensor node.
Abstract: Present two algorithms for tracking and identification in decentralized multi-sensor systems. Decentralized architectures have many benefits in terms of modularity, speed and robustness. The state estimation (tracking) algorithm is a decentralized Kalman filter (DKF) based on the extended Kalman filter. Identification is achieved by the decentralized Bayesian identification (DBI) algorithm, which identifies targets being tracked. For each of the algorithms The authors discuss optimality and the effect of reducing connectivity. The structure of the algorithms leads to the development of an architecture for a modular sensing node based on communication considerations. The authors present example implementations of both algorithms on actual transputer-based sensing nodes. They describe RCD (region of constant depth) tracking and for this develop a monopulse sonar arrangement with which they implement real-time autonomous tracking by a single sensor node. The second example implementation describes identification of targets being tracked by the DKF using the DBI on actual CCD camera-based nodes. >
5 citations
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12 Dec 1991
TL;DR: In this article, the serial bus lines of communication nodes for first and second groups and data-transfer parallel bus line of the communication node for only the first group are equipped to concurrently summarize units, make high speed of treatment, and reduce cost as a whole system.
Abstract: PURPOSE:To concurrently summarize units, make high speed of treatment, and reduce cost as a whole system by equipping the communication serial bus lines of communication nodes for first and second groups and data-transfer parallel bus line of the communication node for only the first group. CONSTITUTION:Controller system nodes (EGI node G, ABS/TRC nodes 7 and 4, WS node 8, and ACS node 10) are interconnected with a parallel bus 11. These four controller system nodes are also connected to a serial bus 1. Also such 'body' system nodes are connected to the serial bus 1 as a vehicle-height sensor node 30 for ACS, hydraulic opening/closing valve node 31 for ACS, wheel- speed sensor 32, node 33 for ABS/TRC brake pressure adjusting valve, handle steered-angle sensor 34, rear-wheel steered-angle sensor node 35 for rear-wheel steering control, motor node 37 for 4WS, acceleration sensor node 38 for ACS, and fuel injection valve node 39 etc.
2 citations