An interference avoidance waveform for the UHF downlink on the new NOAA GOES-R satellite

2017 ◽  
Author(s):  
Brian Kopp ◽  
Duane Preble ◽  
Brett Betsill
Keyword(s):  
Interference Avoidance

scholarly journals Effective Data Transmission and Control Based on Social Communication in Social Opportunistic Complex Networks

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-20 ◽  
Author(s):  
Weiyu Yang ◽  
Jia Wu ◽  
Jingwen Luo
Keyword(s):  
Complex Networks ◽  
Information Transmission ◽  
Interference Cancellation ◽  
Propagation Delay ◽  
Transmission Efficiency ◽  
Successive Interference Cancellation ◽  
Time Slice ◽  
Signal Interference ◽  
Time Signal ◽  
Interference Avoidance

In opportunistic complex networks, information transmission between nodes is inevitable through broadcast. The purpose of broadcasting is to distribute data from source nodes to all nodes in the network. In opportunistic complex networks, it is mainly used for routing discovery and releasing important notifications. However, when a large number of nodes in the opportunistic complex networks are transmitting information at the same time, signal interference will inevitably occur. Therefore, we propose a low-latency broadcast algorithm for opportunistic complex networks based on successive interference cancellation techniques to improve propagation delay. With this kind of algorithm, when the social network is broadcasting, this algorithm analyzes whether the conditions for successive interference cancellation are satisfied between the broadcast links on the assigned transmission time slice. If the conditions are met, they are scheduled at the same time slice, and interference avoidance scheduling is performed when conditions are not met. Through comparison experiments with other classic algorithms of opportunistic complex networks, this method has outstanding performance in reducing energy consumption and improving information transmission efficiency.

scholarly journals A Tutorial on Optical Feeding of Millimeter-Wave Phased Array Antennas for Communication Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-22 ◽  
Author(s):  
Ivan Aldaya ◽  
Gabriel Campuzano ◽  
Gerardo Castañón ◽  
Alejandro Aragón-Zavala
Keyword(s):  
Millimeter Wave ◽  
High Speed ◽  
Phased Array ◽  
Path Loss ◽  
High Gain ◽  
Interference Avoidance ◽  
Amplitude Control ◽  
Phased Array Antennas ◽  
Array Antennas ◽  
The Impact

Given the interference avoidance capacity, high gain, and dynamical reconfigurability, phased array antennas (PAAs) have emerged as a key enabling technology for future broadband mobile applications. This is especially important at millimeter-wave (mm-wave) frequencies, where the high power consumption and significant path loss impose serious range constraints. However, at mm-wave frequencies the phase and amplitude control of the feeding currents of the PAA elements is not a trivial issue because electrical beamforming requires bulky devices and exhibits relatively narrow bandwidth. In order to overcome these limitations, different optical beamforming architectures have been presented. In this paper we review the basic principles of phased arrays and identify the main challenges, that is, integration of high-speed photodetectors with antenna elements and the efficient optical control of both amplitude and phase of the feeding current. After presenting the most important solutions found in the literature, we analyze the impact of the different noise sources on the PAA performance, giving some guidelines for the design of optically fed PAAs.

The Design of a Chain of Spherical Stephenson Mechanisms for a Gearless Robotic Pitch-Roll Wrist

2005 ◽  
Vol 128 (2) ◽  
pp. 422-429 ◽  
Author(s):  
S. Hernandez ◽  
S. Bai ◽  
J. Angeles
Keyword(s):  
Unmodeled Dynamics ◽  
Manufacturing Cost ◽  
Interference Avoidance ◽  
Dimensional Synthesis ◽  
Bevel Gears ◽  
Industrial Manipulators ◽  
Differential Mechanism ◽  
Gear Trains ◽  
Robot Performance ◽  
A Chain

Although bevel-gear robotic wrists are widely used in industrial manipulators due to their simple kinematics and low manufacturing cost, their gear trains function under rolling and sliding, the latter bringing about noise and vibration. Sliding is inherent to the straight teeth of the bevel gears of these trains. Moreover, unavoidable backlash introduces unmodeled dynamics, which mars robot performance. To alleviate these drawbacks, a gearless pitch-roll wrist is currently under development for low backlash and high stiffness. The wrist consists of spherical cam-rollers and spherical Stephenson linkages, besides two roller-carrying disks that drive a combination of cams and Stephenson mechanisms, the whole system rotating as a differential mechanism. The paper focuses on the design of the chain of spherical Stephenson mechanisms. The problem of the dimensional synthesis is addressed, and interference avoidance is discussed. An embodiment of the concept is also included.

Application of Convex Hull for Tool Interference Avoidance in 5-Axis CNC Machining

1996 ◽  
Author(s):  
Yuan-Shin Lee ◽  
Tien-Chien Chang
Keyword(s):  
Convex Hull ◽  
Tool Path ◽  
Correction Method ◽  
Nc Machining ◽  
Cnc Machining ◽  
Free Form ◽  
Interference Avoidance ◽  
Tool Interference ◽  
Free Form Surface ◽  
Free Form Surfaces

Abstract In this paper, a methodology of applying convex hull property in solving the tool interference problem is presented for 5-axis NC machining of free-form surfaces. Instead of exhausted point-by-point checking for possible tool interference, a quick checking can be done by using the convex hull constructed from the control polygon of free-form surface modeling. Global tool interference in 5-axis NC machining is detected using the convex hull of the free-form surface. A correction method for removing tool interference has also been developed to generate correct tool path for 5-axis NC machining. The inter-surface tool interference can be avoided by using the developed technique.

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