• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2010.05a
• /
• pp.535-539
• /
• 2010

This paper include to study DoA(Direction of Arrival) for radio collection and monitoring system. The direction finding calculated by applying the CVDF (Correlation Vector Direction Finding) algorithm for the five circular dipole antenna over V / UHF band. To improve the accuracy of direction finding by applying CVDF algorithm needs to obtain ideal phase difference each antennas. However, a circular array antenna phase difference pattern may be distorted on a specific frequency band or to particular direction. The effect of installing each array antennas circularly and the effect of the interference of center pole (located in the center of a circular array antenna mount) may make the distortion of phase pattern. If you use an active antenna instead of passive antenna to obtain good sensitivity, you would measure the more distortion. This paper propose how to change combination of antennas to measure the phase in real-time and how to use antenna beam patterns for minimizing the degradation phenomena at applying simple CVDF algorithm and increasing the direction finding capability.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.16 no.5
• /
• pp.613-621
• /
• 2013

This paper presents the direction finding proximity fuze sensor using the clutter rejection method and the adaptive target detection algorithm for anti-air missiles. To remove effects by clutter and detect a target accurately, the clutter rejection method of Legendre sequence with BPSK(Bi phase Shift Keying) modulation has been proposed and the Doppler signal which has cross correlation characteristics is obtained from reflected target signals. Considering the change of the Doppler signal, the adaptive target detection algorithm has been developed and the direction finding algorithm has been fulfilled by comparing received powers from adjacent three receiving antennas. The encounter simulation test apparatus was made to collect and analyze reflected signal and test results showed that the -10 dBsm target was detected over 10 meters and the target with mesh clutter was detected and direction was distinguished definitely.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.12 no.1
• /
• pp.97-105
• /
• 2009

In this paper, the performance of AP(Alternating Projection) and EM(Expectation Maximization) algorithms is investigated in terms of detection of multiple signals, resolvability of coherent signals and the efficiency of sensor array processing. The basic idea of these algorithms is utilization of relaxation technique of successive 1D maximization to solve a direction finding problem by maximizing the multidimensional likelihood function. It means that the function is maximized over only for a single parameter while the other parameters are fixed at each step of the iteration. According to simulation results, the algorithms showed good performance for both incoherent and coherent multiple signals. Moreover, some advantages are identified for direction finding with very small samples and fast convergence. The performance of AP algorithm is compared with that of EM using multiple criteria such as the number of sensor, SNR, the number of samples, and convergence speed over uniform circular array. It is resulted AP algorithm is superior to EM overally except for one criterion, convergence speed. Especially, for EM algorithm there is no performance difference between incoherent and coherent case. In conclusion, AP and EM are viable and practical alternatives, which can be applied to a direction under due to the resolvability of multi-path signals, reliable performance and no troublesome eigen-decomposition of the sample-covariance matrix.

• Journal of the Korea Convergence Society
• /
• v.10 no.1
• /
• pp.1-6
• /
• 2019

In this paper, we have studied a direction finding method of the radio signal by comparing the phase difference and its pattern from the uniform circular array antenna. In the phase comparison direction finding, if the length of the antenna baseline is longer than 0.5 wavelength of the incident signal, azimuth ambiguity occurs in which two or more azimuth angles are calculated in the same phase difference. The azimuthal ambiguity is removed by fusing the phase difference of the 5 antennas. The developed ambiguity elimination technology reduces the azimuth error where the antenna baseline is shorter than 1.236 wavelength in the uniform circular array with five antennas. This algorithm is very useful for the design of direction finder of an electronic information system.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.25 no.2
• /
• pp.117-124
• /
• 2022

Single-ring circular array antennas can be applied to direction finding systems in order to use nose-section in other purposes, and the interferometry is a proper direction finding method to those systems. We usually make the interferometer baseline long enough to achieve good angular accuracy. However, an interferometer with baseline longer than a half-wavelength has the ambiguity problem. In this paper, we present a novel method for solving the ambiguity problem in interferometry systems. This technique is based on the amplitude comparison method and the space division table, and it can place a target within the angular region in which the ambiguity problem does not occur by roughly estimating direction-of-arrival. The Monte Carlo simulation results show that proposed method can effectively remove the ambiguity problem in the system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.17 no.4
• /
• pp.379-386
• /
• 1992

In this paper a direction finding method which can which can estimate the direction angles of source signals impinging on the sensor array in which sensor noises are correlated is studied. This method performs the estimation of source direction angles form sensors, regardless of sensor noise correlation, by eliminating the sensor noise correlation coefficient which can be accurately estimated. Finally, this paper shows, through the computer simulation, that the proposed, method is extremely useful and superior when there exists the noise correlation between sensors, .

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.6
• /
• pp.567-575
• /
• 2017

The direction finder is an important device for an electronic support(ES) system because it is responsible for finding the direction of an emitter. The higher the accuracy of the direction finding, the higher the vitality of the weapon system with the ES system. Recently, the direction error occurred in the operating shipboard ES system when direction finding was performed for the signal with a pulse width of 200 ns. Therefore, this paper proposes, an improved method to reduce the direction error for shipboard ES systems. The proposed method was applied to the operating shipboard ES system and a field test was performed. The results of the field test showed that the direction error was reduced significantly for the signal with a pulse width of 200 ns.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.6 s.97
• /
• pp.549-555
• /
• 2005

This paper describes a microwave direction finding technology which is used for RF signal acquisition and monitoring systems. This paper suggests a direction finding method which use a combination of the amplitude-comparison technology and the phase-comparison technology. The amplitude-comparison technology uses the amplitude difference of the RF signals received from the array antennas of direction finding system and removes the ambiguity of wave incident bearing. The phase-comparison technology uses the phase difference of the RF signals received from the same nay antennas and makes a good direction finding accuracy. The suggested direction finding technology is designed to place 8 array antennas in a $45^{\circ}$ distance around the circle for $360^{\circ}$ azimuth angle. Also it is designed to use the phase difference of the received signals ken two nearby antennas to measure the signal incident direction accurately and to use the amplitude difference to remove the ambiguity of wave incident bearing. The simulation and measurement results are under $0.5^{\circ}$ bearing error in $2.0\~6.0$ GHz when SNR is 30 dB.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.9
• /
• pp.2157-2163
• /
• 2010

This paper includes the study of DOA(Direction of Arrival). CVDF(Correlative Vector Direction Finding) algorithm using at the phase difference each antenna needs to obtain ideal sinusoidal phase difference patterns. However, the phase difference patterns of circular array antennas may be interfered on a specific frequency band and to particular angle. The effect of installing each array antenna circularly and the effect of the interference by center pole (located in the center of a circular array antennas) may distort the phase difference patterns. This paper propose how to change the combination of antennas to measure phase difference patterns in real-time and how to use antenna beam patterns for minimizing the degradation phenomena with old CVDF algorithm. According to the test result, the capability of direction finding is improved.

• Journal of the Korea Convergence Society
• /
• v.6 no.5
• /
• pp.249-255
• /
• 2015

In this paper, we present an azimuth error analysis for the correlative interferometer direction finding. The correlative interferometer is a direction finding method that compares the theoretical and measured phase differences. The direction of the radio transmitter can be estimated by obtaining the maximum correlation between two data sets. We used a 5-element circular array antennas arranged in a circle. To derive the correlation function between antenna elements, we assume that the incident plane wave arrives from a certain angle and the phase difference of each antenna can be derived by comparing with the reference. The suggested direction finding gives a relatively accurate result even if the radio transmitter is located in the higher altitude.