Multiple target DOA estimation by exploiting knowledge of the antenna main beam pattern

2003 ◽  
Author(s):  
A. Farina ◽  
F. Gini ◽  
M. Greco
Keyword(s):  
Doa Estimation ◽  
Beam Pattern ◽  
Main Beam ◽  
Multiple Target

scholarly journals Synthesis of Steered Flat-top Beam Pattern Using Evolutionary Algorithm

2016 ◽  
Vol 5 (3) ◽  
pp. 86 ◽  
Author(s):  
D. Mandal ◽  
K. S. Kola ◽  
J. Tewary ◽  
V. P. Roy ◽  
A. K. Bhattacharjee
Keyword(s):  
Evolutionary Algorithm ◽  
Dynamic Range ◽  
Synthesis Method ◽  
Elevation Angle ◽  
Differential Evolution Algorithm ◽  
Beam Pattern ◽  
Main Beam ◽  
Pattern Synthesis ◽  
Feed Networks ◽  
Flat Top Beam

In this paper a pattern synthesis method based on Evolutionary Algorithm is presented. A Flat-top beam pattern has been generated from a concentric ring array of isotropic elements by finding out the optimum set of elements amplitudes and phases using Differential Evolution algorithm. The said pattern is generated in three predefined azimuth planes instate of a single phi plane and also verified for a range of azimuth plane for the same optimum excitations. The main beam is steered to an elevation angle of 30 degree with lower peak SLL and ripple. Dynamic range ratio (DRR) is also being improved by eliminating the weakly excited array elements, which simplify the design complexity of feed networks.

scholarly journals Calibration and performance of the NIKA2 camera at the IRAM 30-m Telescope

2020 ◽  
Vol 637 ◽  
pp. A71 ◽  
Author(s):  
L. Perotto ◽  
N. Ponthieu ◽  
J. F. Macías-Pérez ◽  
R. Adam ◽  
P. Ade ◽  
...  
Keyword(s):  
Flux Density ◽  
Calibration Method ◽  
Beam Pattern ◽  
Alternative Methods ◽  
Dual Band ◽  
Main Beam ◽  
Kinetic Inductance ◽  
Baseline Method ◽  
Data Set ◽  
Wide Range

Context. NIKA2 is a dual-band millimetre continuum camera of 2 900 kinetic inductance detectors, operating at 150 and 260 GHz, installed at the IRAM 30-m telescope in Spain. Open to the scientific community since October 2017, NIKA2 will provide key observations for the next decade to address a wide range of open questions in astrophysics and cosmology. Aims. Our aim is to present the calibration method and the performance assessment of NIKA2 after one year of observation. Methods. We used a large data set acquired between January 2017 and February 2018 including observations of primary and secondary calibrators and faint sources that span the whole range of observing elevations and atmospheric conditions encountered by the IRAM 30-m telescope. This allowed us to test the stability of the performance parameters against time evolution and observing conditions. We describe a standard calibration method, referred to as the “Baseline” method, to translate raw data into flux density measurements. This includes the determination of the detector positions in the sky, the selection of the detectors, the measurement of the beam pattern, the estimation of the atmospheric opacity, the calibration of absolute flux density scale, the flat fielding, and the photometry. We assessed the robustness of the performance results using the Baseline method against systematic effects by comparing results using alternative methods. Results. We report an instantaneous field of view of 6.5′ in diameter, filled with an average fraction of 84%, and 90% of valid detectors at 150 and 260 GHz, respectively. The beam pattern is characterised by a FWHM of 17.6″ ± 0.1″ and 11.1″ ± 0.2″, and a main-beam efficiency of 47%±3%, and 64%±3% at 150 and 260 GHz, respectively. The point-source rms calibration uncertainties are about 3% at 150 GHz and 6% at 260 GHz. This demonstrates the accuracy of the methods that we deployed to correct for atmospheric attenuation. The absolute calibration uncertainties are of 5%, and the systematic calibration uncertainties evaluated at the IRAM 30-m reference Winter observing conditions are below 1% in both channels. The noise equivalent flux density at 150 and 260 GHz are of 9 ± 1 mJy s1/2 and 30 ± 3 mJy s1/2. This state-of-the-art performance confers NIKA2 with mapping speeds of 1388 ± 174 and 111 ± 11 arcmin2 mJy−2 h−1 at 150 and 260 GHz. Conclusions. With these unique capabilities of fast dual-band mapping at high (better that 18″) angular resolution, NIKA2 is providing an unprecedented view of the millimetre Universe.

scholarly journals Constant-Modulus-Waveform Design for Multiple-Target Detection in Colocated MIMO Radar

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 4040 ◽  
Author(s):  
Bingfan Liu ◽  
Baixiao Chen ◽  
Minglei Yang
Keyword(s):  
Target Detection ◽  
Optimization Problems ◽  
Design Method ◽  
Waveform Design ◽  
Mimo Radar ◽  
Beam Pattern ◽  
Constant Modulus ◽  
Multiple Target ◽  
Beam Design ◽  
Detection Probabilities

For improving the performance of multiple-target detection in a colocated multiple-input multiple-output (MIMO) radar system, a constant-modulus-waveform design method is presented in this paper. The proposed method consists of two steps: simultaneous multiple-transmit-beam design and constant-modulus-waveform design. In the first step, each transmit beam is controlled by an ideal orthogonal waveform and a weight vector. We optimized the weight vectors to maximize the detection probabilities of all targets or minimize the transmit power for the purpose of low intercept probability in the case of predefined worst detection probabilities. Various targets’ radar cross-section (RCS) fluctuation models were also considered in two optimization problems. Then, the optimal weight vectors multiplied by ideal orthogonal waveforms were a set of transmitted waveforms. However, those transmitted waveforms were not constant-modulus waveforms. In the second step, the transmitted waveforms obtained in the first step were mapped to constant-modulus waveforms by cyclic algorithm. Numerical examples are provided to show that the proposed constant-waveform design method could effectively achieve the desired transmit-beam pattern, and that the transmit-beam pattern could be adaptively adjusted according to prior information.

scholarly journals Direction of Arrival Estimation using Conventional Subspace Algorithms

2019 ◽  
Vol 8 (9) ◽  
pp. 815-819
Keyword(s):  
Array Signal Processing ◽  
Direction Of Arrival ◽  
Doa Estimation ◽  
Research Area ◽  
Minimum Variance ◽  
Spatial Spectrum ◽  
Basic Knowledge ◽  
Main Beam ◽  
Spectrum Estimation ◽  
Minimum Variance Distortionless Response

In recent times, Direction of Arrival (DOA) Estimation study earns attention in array signal processing and it develops rapidly in several application such as sonar, radar, communication, biomedicine and seismology measurements. The self adaption and spatial spectrum are the broad research area in array processing. The spatial spectrum estimation focused on the signal distribution in the space is received from all direction to receiver. To maintain accuracy in DOA estimation for the antenna array the basic knowledge is required for main beam, and side lobes pattern must be small to suppress signal from other direction. This paper discussed the overview of the Direction of Arrival (DOA) estimation based on classical Sum and delay beamformer, Minimum Variance Distortionless Response (MVDR) technique, Min Norm technique and Multiple Signal Classification(MUSIC) by using the spatial spectrum parameters.

scholarly journals Characterisation of the Mopra Radio Telescope at 16–50 GHz

2010 ◽  
Vol 27 (3) ◽  
pp. 321-330 ◽  
Author(s):  
J. S. Urquhart ◽  
M. G. Hoare ◽  
C. R. Purcell ◽  
K. J. Brooks ◽  
M. A. Voronkov ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Full Width Half Maximum ◽  
Beam Pattern ◽  
Main Beam ◽  
Beam Power ◽  
Beam Size ◽  
Frequency Range ◽  
Beam Shape ◽  
Radial Beam ◽  
Power Pattern

AbstractWe present the results of a programme of scanning and mapping observations of astronomical masers and Jupiter designed to characterise the performance of the Mopra Radio Telescope at frequencies between 16 and 50 GHz using the 12-mm and 7-mm receivers. We use these observations to determine the telescope beam size, beam shape, and overall telescope beam efficiency as a function of frequency. We find that the beam size is well fit by λ/D over the frequency range with a correlation coefficient of ∼90%. We determine the telescope main beam efficiencies are between ∼48 and 64% for the 12-mm receiver and reasonably flat at ∼50% for the 7-mm receiver. Beam maps of strong H2O (22 GHz) and SiO masers (43 GHz) provide a means to examine the radial beam pattern of the telescope. At both frequencies, the radial beam pattern reveals the presence of three components: a central ‘core’, which is well fit by a Gaussian and constitutes the telescopes main beam; and inner and outer error beams. At both frequencies, the inner and outer error beams extend out to ∼2 and ∼3.4 times the full-width half maximum of the main beam, respectively. Sources with angular sizes of a factor of two or more larger than the telescope main beam will couple to the main and error beams, and therefore the power contributed by the error beams needs to be considered. From measurements of the radial beam power pattern we estimate the amount of power contained in the inner and outer error beams is of order one-fifth at 22 GHz, rising slightly to one-third at 43 GHz.

scholarly journals Optimization of array geometry for direction-of-arrival estimation using a priori information

2010 ◽  
Vol 8 ◽  
pp. 87-94 ◽  
Author(s):  
O. Lange ◽  
B. Yang
Keyword(s):  
Mean Squared Error ◽  
A Priori ◽  
Geometry Optimization ◽  
Direction Of Arrival ◽  
Doa Estimation ◽  
Beam Pattern ◽  
Side Lobe Level ◽  
Estimation Errors ◽  
Estimation Performance ◽  
Array Geometry

Abstract. This paper focuses on the estimation of the direction-of-arrival (DOA) of signals impinging on a sensor array. A novel method of array geometry optimization is presented that improves the DOA estimation performance compared to the standard uniform linear array (ULA) with half wavelength element spacing. Typically, array optimization only affects the beam pattern of a specific steering direction. In this work, the proposed objective function incorporates, on the one hand, a priori knowledge about the signal's DOA in terms of a probability density function. By this means, the array can be adjusted to external conditions. On the other hand, a modified beam pattern expression that is valid for all possible signal directions is taken into account. By controlling the side lobe level and the beam width of this new function, DOA ambiguities, which lead to large DOA estimation errors, can be avoided. In addition, the DOA fine error variance is minimized. Using a globally convergent evolution strategy, the geometry optimization provides array geometries that significantly outperform the standard ULA with respect to DOA estimation performance. To show the quality of the algorithm, four optimum geometries are presented. Their DOA mean squared error is evaluated using the well known deterministic Maximum Likelihood estimator and compared to the standard ULA and theoretical lower bounds.

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