Aberration of a microwave holographic imaging system over a line-of-sight propagation path

1977 ◽  
Vol 25 (6) ◽  
pp. 860-863
Author(s):  
Y. Ja
Author(s):  
Kuniyuki Motojima ◽  
Kousuke Tanigawa ◽  
Nozomi Haga

Abstract. Research of the geophysical electromagnetic phenomena with seismic activity is important for hazard-resistant strategy. Many papers which indicate the existence of geophysical electromagnetic phenomena associated with earthquakes are reported frequently. Anomalous propagation in the radio waves is sometimes related with earthquakes. In previous paper, authors proposed a new concept to estimate the relation between earthquakes and anomalous line-of-sight propagation in VHF band by statistical approach. Event probability of the anomalous line-of-sight propagation increased just a few days prior to earthquakes. In this paper, we investigated a new relationship between anomalous fluctuations in the radio waves, which propagated from line-of-sight region, and occurrences of earthquake by using statistical analysis. Monitoring the strength of radio waves and detecting the anomalous fluctuations by using a new original method, we can obtain the high probability which indicates strong relation between the anomalous propagation and occurrences of earthquake. After the stochastic consideration, we can find out the anomalous fluctuations, which appear one day prior to earthquakes near the wave propagation path.


Author(s):  
Vyacheslav Begishev ◽  
Edward Sopin ◽  
Dmitri Moltchanov ◽  
Andrey Samuylov ◽  
Yuliya Gaidamaka ◽  
...  

Introduction: In 3GPP New Radio (NR) systems, frequent radio propagation path blockages can lead to the disconnection of ongoingsessions already accepted into the system, reducing the quality of service in the network. Controlling access to system resource byprioritizing for the ongoing sessions can increase the session continuity. In this paper, we propose resource allocation with a reservationmechanism. Purpose: Development of a mathematical model for analyzing the effect of this mechanism on other system performanceindicators – dropping probabilities for new and ongoing sessions and system utilization. The model takes into account the key featuresof the 3GPP NR technology, including the height of the interacting objects, the spatial distribution and mobility of the blockers, as wellas the line-of-sight propagation properties between the transceivers for mmWave NR technology. Results: We analyzed the reservationmechanism with the help of a developed model in the form of a resource queueing system with signals, where the base station bandwidthcorresponds to the resource, and the signals model a change in the line-of-sight conditions between the receiving and transmittingdevices. Creating a priority for ongoing sessions whose service has not yet been completed provides a considerable flexibility forbalancing the session continuity and dropping of a new session, with a slight decrease in the efficiency of the radio resource utility. Withthe developed model, we showed that reserving even a small bandwidth (less than 10% of the total resources) to maintain the ongoingsessions has a positive effect on their continuity, as it increases the probability of their successful completion. Practical relevance: The proposed mechanism works more efficiently in overload conditions and with sessions which have a high data transfer raterequirements. This increases the demand for the proposed mechanism in 5G NR communication systems.


2020 ◽  
Author(s):  
Florian Willomitzer ◽  
Prasanna Rangarajan ◽  
Fengqiang Li ◽  
Muralidhar Balaji ◽  
Marc Christensen ◽  
...  

Abstract The presence of a scattering medium in the imaging path between an object and an observer is known to severely limit the visual acuity of the imaging system. We present an approach to circumvent the deleterious effects of scattering, by exploiting spectral correlations in scattered wavefronts. Our Synthetic Wavelength Holography (SWH) method is able to recover a holographic representation of hidden targets with high resolution over a wide field of view. The complete object field is recorded in a snapshot-fashion, by monitoring the scattered light return in a small probe area. This unique combination of attributes opens up a plethora of new Non-Line-of-Sight imaging applications ranging from medical imaging and forensics, to early-warning navigation systems and reconnaissance. Adapting the findings of this work to other wave phenomena will help unlock a wider gamut of applications beyond those envisioned in this paper.


2020 ◽  
Vol 10 (20) ◽  
pp. 7119
Author(s):  
Jihong Xiu ◽  
Pu Huang ◽  
Jun Li ◽  
Hongwen Zhang ◽  
Youyi Li

In recent years, applications such as marine search and rescue, border patrol, etc. require electro-optical equipment to have both high resolution and precise geographic positioning abilities. The step and stare working based on a composite control system is a preferred solution. This paper proposed a step and stare system composed of two single-axis fast steering mirrors and a two-axis gimbal. The fast steering mirrors (FSMs) realize image motion compensation and the gimbal completes pointing control. The working principle and the working mode of the system are described first. According to the imaging optical path, the algorithm and control flow of the line of sight (LOS) and image motion compensation are developed. The proposed method is verified through ground imaging and flight tests. Under the condition of flight, the pointing accuracy of the target can be controlled within 15 m. The proposed algorithm can achieve effective motion compensation and get high-resolution images. This achieves high resolution and accurate LOS simultaneously.


1993 ◽  
Vol 32 (22) ◽  
pp. 4128
Author(s):  
F. Carreño ◽  
J. L. Ruiz ◽  
J. M. Vázquez ◽  
R. Benárdez ◽  
J. L. Hernández ◽  
...  

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