45° aligned dual-polarizer for the suppression of signal fading in polarization OTDR

2021 ◽  
Vol 60 (6) ◽  
pp. 1603
Author(s):  
Xuefeng Wang ◽  
Can Zhao ◽  
Hao Wu ◽  
Ruolin Liao ◽  
Li Shen ◽  
...  
Keyword(s):  
Signal Fading

scholarly journals Spectral characteristics of spring arctic mesosphere dynamics

1998 ◽  
Vol 16 (12) ◽  
pp. 1607-1618 ◽  
Author(s):  
C. M. Hall ◽  
A. H. Manson ◽  
C. E. Meek
Keyword(s):  
Energy Dissipation ◽  
Middle Atmosphere ◽  
Spectral Characteristics ◽  
Turbulent Energy ◽  
Energy Dissipation Rate ◽  
Spectral Signature ◽  
Upper Limits ◽  
Waves And Tides ◽  
Signal Fading ◽  
Mf Radar

Abstract. The spring of 1997 has represented a stable period of operation for the joint University of Tromsø / University of Saskatchewan MF radar, being between refurbishment and upgrades. We examine the horizontal winds from the February to June inclusive and also include estimates of energy dissipation rates derived from signal fading times and presented as upper limits on the turbulent energy dissipation rate, ε. Here we address the periodicity in the dynamics of the upper mesosphere for time scales from hours to one month. Thus, we are able to examine the changes in the spectral signature of the mesospheric dynamics during the transition from winter to summer states.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; turbulence; waves and tides).

Wireless Networks

2017 ◽  
pp. 80-94
Author(s):  
Monika Rani ◽  
Harish Kumar
Keyword(s):  
Ad Hoc ◽  
Mobile Ad Hoc Network ◽  
Propagation Model ◽  
Wireless Devices ◽  
Limited Bandwidth ◽  
Intermittent Connectivity ◽  
Greedy Forwarding ◽  
Moving Vehicles ◽  
Signal Fading ◽  
Wireless Infrastructure

VANET is a type of Mobile Ad-hoc network (MANET) that provides wireless communication between close by moving vehicles as well as between vehicles and road side fixed equipment. It requires the vehicles to be equipped with sensors and wireless devices and fixed roadside wireless infrastructure. There are number of research issues like Highly Dynamic Topology, Signal fading, Limited Bandwidth, Intermittent Connectivity, Mobility Modelling, Propagation Model, Routing which needs attention. The scope of this chapter is focused on various advances in Greedy Forwarding routing techniques. Various VANET routing protocols are reviewed and compared in this chapter.

Short term characteristics of ion-acoustic type radio auroral echoes

1978 ◽  
Vol 56 (2) ◽  
pp. 292-301 ◽  
Author(s):  
Christos Haldoupis ◽  
George Sofko
Keyword(s):  
Signal Amplitude ◽  
Acoustic Velocity ◽  
Velocity Range ◽  
Short Term ◽  
Backscatter Signal ◽  
Ion Acoustic ◽  
Longitudinal Plasma ◽  
Digital Demodulation ◽  
Signal Fading ◽  
Time Sequences

Digital demodulation techniques and spectral analysis are used to study the short term (<1 s) characteristics of the ion-acoustic radio auroral echoes. Examination of 0.4 s time sequences indicates that the signal amplitude undergoes a deep and quasi-periodic fading with strongly marked periodicities in the 2–10 Hz range. Evidence shows that the fading is not due to interference but to the appearance and disappearance of independent scatterers, causing a sequence of backscatter signal bursts. If the assumption is made that these scatterers are longitudinal plasma density waves, the observed signal fading can be interpreted in terms of the growth and decay of individual regions of plasma instability rather than as interference between signals from separated coexisting scattering regions. Investigation of a large number of records suggests the following features for the irregularities associated with the ion-acoustic echoes: (1) their lifetime is in the 0.05–0.25 s range. (2) their growth (or decay) rate is in the 10–60 s−1 range, (3) their velocity remains fairly constant, even during growth and decay, and is always within the ion-acoustic velocity range in the medium.

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