A phase correction technique based on spatial movements of antennas in real-time for designing self-adapting conformal array antennas

2017 ◽  
Vol 59 (12) ◽  
pp. 3002-3010 ◽  
Author(s):  
Sayan Roy ◽  
Sayeed Sajal ◽  
Benjamin D. Braaten
Keyword(s):  
Real Time ◽  
Phase Correction ◽  
Conformal Array ◽  
Array Antennas ◽  
Correction Technique

scholarly journals Shape and excitation optimization for conformal array antennas

Radio Science ◽  
2008 ◽  
Vol 43 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
T. Halleröd ◽  
T. Rylander
Keyword(s):  
Conformal Array ◽  
Array Antennas

Fourier-Domain Analysis of Complex Line Shapes

1989 ◽  
Vol 43 (1) ◽  
pp. 38-44 ◽  
Author(s):  
J. M. Bostick ◽  
L. A. Carreira
Keyword(s):  
Phase Correction ◽  
Fourier Domain ◽  
Phase Information ◽  
Line Shapes ◽  
Target Spectrum ◽  
Correction Technique ◽  
Subsequent Phase ◽  
Domain Phase ◽  
Anti Stokes ◽  
Previous Phase

The development of a method of phase correction is discussed. Previous phase-correction methods have often required the input of an operator in order to extract phase information from the target spectrum. The use of this Fourier-domain phase-correction technique is discussed specifically in terms of its application to coherent anti-Stokes Raman spectra. The extraction of phase information and subsequent phase correction are discussed.

scholarly journals A Novel Tilt Correction Technique for Irradiance Sensors and Spectrometers On-Board Unmanned Aerial Vehicles

2018 ◽  
Vol 10 (12) ◽  
pp. 2068 ◽  
Author(s):  
Juha Suomalainen ◽  
Teemu Hakala ◽  
Raquel Alves de Oliveira ◽  
Lauri Markelin ◽  
Niko Viljanen ◽  
...  
Keyword(s):  
Real Time ◽  
Remote Sensing Data ◽  
Correction Method ◽  
Aerial Images ◽  
Aerial Image ◽  
Optical Remote Sensing ◽  
Processing Unit ◽  
Atmospheric Conditions ◽  
Tilt Correction ◽  
Correction Technique

In unstable atmospheric conditions, using on-board irradiance sensors is one of the only robust methods to convert unmanned aerial vehicle (UAV)-based optical remote sensing data to reflectance factors. Normally, such sensors experience significant errors due to tilting of the UAV, if not installed on a stabilizing gimbal. Unfortunately, such gimbals of sufficient accuracy are heavy, cumbersome, and cannot be installed on all UAV platforms. In this paper, we present the FGI Aerial Image Reference System (FGI AIRS) developed at the Finnish Geospatial Research Institute (FGI) and a novel method for optical and mathematical tilt correction of the irradiance measurements. The FGI AIRS is a sensor unit for UAVs that provides the irradiance spectrum, Real Time Kinematic (RTK)/Post Processed Kinematic (PPK) GNSS position, and orientation for the attached cameras. The FGI AIRS processes the reference data in real time for each acquired image and can send it to an on-board or on-cloud processing unit. The novel correction method is based on three RGB photodiodes that are tilted 10° in opposite directions. These photodiodes sample the irradiance readings at different sensor tilts, from which reading of a virtual horizontal irradiance sensor is calculated. The FGI AIRS was tested, and the method was shown to allow on-board measurement of irradiance at an accuracy better than ±0.8% at UAV tilts up to 10° and ±1.2% at tilts up to 15°. In addition, the accuracy of FGI AIRS to produce reflectance-factor-calibrated aerial images was compared against the traditional methods. In the unstable weather conditions of the experiment, both the FGI AIRS and the on-ground spectrometer were able to produce radiometrically accurate and visually pleasing orthomosaics, while the reflectance reference panels and the on-board irradiance sensor without stabilization or tilt correction both failed to do so. The authors recommend the implementation of the proposed tilt correction method in all future UAV irradiance sensors if they are not to be installed on a gimbal.

Phase Aberration Correction in Two Dimensions Using a Deformable Array Transducer

1995 ◽  
Vol 17 (3) ◽  
pp. 227-247
Author(s):  
Loriann L. Ries ◽  
Stephen W. Smith
Keyword(s):  
Adaptive Optics ◽  
Ultrasonic Transducer ◽  
Phase Correction ◽  
Two Dimensions ◽  
Ultrasound Images ◽  
Two Dimensional ◽  
Ultrasound Beam ◽  
Dimensional Array ◽  
Electronic Phase ◽  
Correction Technique

Phase aberrations due to tissue inhomogeneities degrade medical ultrasound images by disrupting the ultrasound beam focus. Currently, phase correction algorithms are implemented by adjusting the electronic phase delays used to steer and focus the ultrasound beam. This means that a two-dimensional array is necessary to completely correct two-dimensional aberrations in tissue. However, two-dimensional arrays are a complex option due to their large number of elements and poor sensitivity. Instead of using a full two-dimensional array, a new technique is proposed, similar to one used in adaptive optics, which uses a deformable transducer of significantly fewer channels for two-dimensional phase correction. Phase correction in azimuth is achieved by altering the electronic phase delay of the element. However, phase correction in elevation is achieved by tilting the element in elevation with a piezoelectric actuator. Comparison of simulations of the new phase correction transducer versus the conventional phase correction technique have shown that a deformable 1 × N or 2 × N transducer can approach the image quality of a 4 × N two-dimensional array or greater. A prototype 1 times 32 array with eight low frequency piezoelectric actuators has been constructed such that every four ultrasonic transducer elements in azimuth are mounted on one independently controlled actuator. This prototype transducer was used to test the ability of a deformable array to produce real time phased array scans and to simulate on-line phase correction by tilting the elements in the elevation direction.

The Research of DOA Estimation Algorithms in the Conformal Array Antenna

2015 ◽  
Vol 743 ◽  
pp. 471-473
Author(s):  
C.Z. Sun
Keyword(s):  
Doa Estimation ◽  
Array Antenna ◽  
Signal Subspace ◽  
Music Algorithm ◽  
Estimation Algorithms ◽  
Conformal Array ◽  
Array Antennas ◽  
Peak Search ◽  
Simulation Results ◽  
Rayleigh Limit

To the conformal array antennas, the conventional DOA estimation algorithms will be affected by the Rayleigh limit. While, the MUSIC algorithm can solve this problem, it fully utilizes the orthogonality of noise subspace and signal subspace. It can achieve the DOA estimation through the spectrum peak search. The MUSIC algorithm is analyzed. Based on the cylindrical and conical array antenna, the algorithms are simulated. The simulation results show that the array arrangement mode can exert an important influence on the DOA estimation.

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