RU-2861599-C1 - METHOD FOR AMPLITUDE DIRECTION FINDING BY LINEAR ANTENNA

Abstract

FIELD: hydroacoustics. SUBSTANCE: invention can be used in the design of a receiving path of a hydroacoustic station with a linear extended antenna. The essence: in a method for amplitude direction finding by a linear antenna consisting of N omnidirectional receivers with the formation of a fan of directional responses (DR) in a 360° viewing sector, wherein the received signals in each DR are processed in receiving channels, at the output of which the level of the output signal is formed, the signal levels in the channels are determined and the channel with the maximum signal value and two other channels are selected, and based on the ratio of signal levels in the selected channels based on interpolation, the bearing of the received signal is determined, wherein a fan of 2N+1 directional responses is formed in the compensation angle sector of ±90° relative to the plane passing through the centre of the antenna perpendicular to its axis, with the intersection of each (m-1)-th DR with the (m+1)-th DR at a level of at least 0.7 at the upper frequency of the signal reception band, to determine the bearing angle of the received signal based on interpolation for the bow and stern channels, two adjacent channels are selected on one side of the channel with the maximum signal, and for the remaining channels, adjacent channels are selected on each side of the channel with the maximum signal level, based on the ratio of signal levels in the three selected receiving channels, the bearing angle of the signal is calculated by interpolation, the systematic error of determining the bearing angle of the received signal is approximated based on the calculated DR within the selected bearing angle sector, and the refined value of the bearing angle and the signal bearing is determined by compensating for the calculated systematic error. EFFECT: increasing noise immunity and reducing the error of amplitude direction finding for linear antennas, including near the bow (bearing=0°) and stern (bearing=180°) receiving channels due to a reduction in systematic error. 2 cl, 4 dwg

Inventors

• MAKAROV NIKOLAJ ALEKSANDROVICH
• Mnatsakanyan Aleksandr Ashetovich
• KULAKOV ANTON KHAKIMOVICH

Dates

Publication Date

20260506

Application Date

20250303

Claims (2)

1. 1. A method of amplitude direction finding, including receiving a signal by N receivers with the formation of a fan of directivity characteristics (DC) in a 360° viewing sector, in which the received signals in each DC are processed in receiving channels, at the output of which the output signal level is formed, the signal levels in the channels are determined and the channel with the maximum signal value and two more channels are selected, and based on the ratio of the signal levels in the selected channels, the bearing of the received signal is determined based on interpolation, characterized in that on a linear antenna consisting of N non-directional receivers, a fan of 2N+1 directivity characteristics is formed in a sector of compensation angles of ±90° relative to a plane passing through the center of the antenna perpendicular to its axis, with the intersection of each (m-1)-th DC with the (m+1)-th DC at a level of at least 0.7 at the upper frequency of the signal reception band, to determine the heading angle of the received signal based on interpolation for the bow and stern channels, two adjacent channels are selected with on one side of the channel with the maximum signal, and for the remaining channels, adjacent channels are selected on each side of the channel with the maximum signal level, the course angle of the signal is calculated based on the ratio of signal levels in the three selected receiving channels, the systematic error in determining the course angle of the received signal is approximated based on the calculated HC within the selected sector of course angles, and the refined value of the course angle and bearing of the signal is determined by compensating for the calculated systematic error.
2. 2. The method according to paragraph 1, characterized in that for the bow and stern channels, for the channel most distant from the channel with the maximum signal level, an additional shift of the XH axis is introduced towards the maximum signal in such a way that the minimum value of the normalized XH within the selected sector of course angles at the upper frequency of the signal reception band is not less than 0.5.

Description

The invention relates to the field of hydroacoustics and can be used in the design of a receiving path for a hydroacoustic station (HAS) with a linear extended antenna. Hydroacoustic stations with linear extended antennas are widely used on surface ships and submarines in the form of towed means of detecting underwater objects [Simonenko S, Andreev M, Klishin V, Okhrimenko S. New generation of hydroacoustic stations with flexible extended towed antennas for surface ships // Marine collection. - No. 9 (1905). - 2005. - P. 44-46]. The feasibility of using flexible extended towed antennas (FLTA) stems from their ability to provide 360° coverage by forming a fan-shaped pattern of directivity characteristics (RCCs). Furthermore, large-wavelength antennas can achieve high antenna directivity, resulting in a sufficiently high concentration coefficient in the low-frequency range and low direction-finding error. Traditional formation of the XN fan of linear antennas [Smaryshev M.D. Directivity of hydroacoustic antennas //L.: Sudostroenie. - 1973. - P. 140], is carried out by introducing phase delays of signals at the antenna receivers, providing a shift of the XN axes by a given angle relative to the plane perpendicular to the antenna axis and passing through its center. In this case, it is considered that the antenna axis, in particular for towed antennas, coincides with the antenna heading and the towing ship heading. In some cases, the heading sensor is built directly into the antenna and the antenna heading coincides with the antenna axis and the towing direction. In the receiving path, a fan of spatial channels (SC) is formed on the basis of the XN fan, to which heading angles (CA) are assigned. By analogy with ship (hull) antennas, CA = 0° coincides with the antenna heading. The starboard antenna gain is positive (from 0° to 180°), while the port antenna gain is negative (from 0° to -180°). When a target is detected in the receiving path, its gain is determined, and the target's bearing is calculated as the sum of the target's gain and the antenna heading. In the following description of the linear antenna direction finding method, it is assumed that the antenna heading is known, and determining the target's gain allows one to calculate its bearing. Among the main requirements that a sonar with a gas-powered sonar must satisfy is the formation of the required characterization pattern in the operating frequency range, ensuring the required target detection quality and spatial resolution. However, as noted in [Koryakin Yu.A., Smirnov S.A., Yakovlev G.V. Shipborne hydroacoustic equipment: status and current issues. - St. Petersburg: Nauka. - P. 66], direction finding accuracy (DF) is one of the "bottlenecks" of a sonar with a gas-powered sonar. According to optimistic estimates, the DF of a sonar with a gas-powered sonar is 1° - 2° at abeam heading angles (CU) and 5° at bow and stern CU. As follows from [Smaryshev M.D. Directivity of hydroacoustic antennas //L.: Sudostroenie. - 1973. - P.110], at compensation angles of the XH of a linear antenna α 0 = ±90°, the width of the XH Δθ increases to a value approximately equal to Δθ = 108°√(λ/L), where λ is the wavelength, L is the linear dimension of the antenna. For antenna wave dimensions L≈20λ, the width of the XH for KU=180° will be about 24°. As indicated in [Ryzhikov A.V., Barsukov Yu.V. Systems and Means of Signal Processing in Hydroacoustics: Textbook. SPb.: ETU "LETI". - 2007. - P.88], it is generally accepted that the accuracy of bearing measurement based on the maximum value of the directivity characteristic is determined by the width of the directivity characteristic. The use of phase or correlation methods of direction finding in some cases allows to increase the accuracy of direction finding by 3-5 times [Maly V.V., Maksimov M.S. Modeling of Working Zones of a Given Accuracy of Target Location Determination by the Direction Finding Method for Hydroacoustic Equipment with Linear Extended Antennas // Hydroacoustics. - No. 57 (1). - 2024. - P.80], however, for linear antennas near KU=0° and KU=180°, phase and correlation methods do not work, since the projection of the base between receivers implementing correlation direction finding methods onto the direction along the antenna axis is close to zero. A known [Tynyankin S.I., Apultsyna I.V., Burtsev S.Yu.; Military Unit 11135. Method for Signal Source Direction Finding. Russian Federation Patent No. 2192651, IPC G01S 3/00, 3/14. No. 98113047/09; Claimed 02.07.1998; Published 10.11.2002, Bulletin No. 31] method for increasing the efficiency of direction finding of the receiving path of a hydroacoustic station with a linear equidistant antenna array (LEAR) when the signal source is positioned along the antenna axis by using a second LEAR located perpendicular to the first LEAR. However, this method requires at least a doubling of the equipment and is unacceptable for towed hydroacoustic systems. A method for am