Vector Marine Electronics Ltd. took part in the 6th Russian scientific conference "Ecology 2011 – The Sea and the Man" held in Taganrog Technological Institute of SFedU in September, 21-23. A.N.Dolgov, Director-Chief designer, and M.A.Raskita, senior research assistant, made a report at the conference «Sonar signal simulator designed for debugging research sonar equipment used for aquatic bioresourses monitoring».
A.N. Dolgov, M.A. Raskita
SONAR SIGNAL SIMULATOR DESIGNED FOR DEBUGGING RESEARCH SONAR EQUIPMENT USED FOR AQUATIC BIORESOURSES MONITORING
The paper offers the description of the Sonar Signal Simulator software developed by Vector Marine Electronics, Ltd. specialists. The Simulator is intended for system debugging the control and display console as a part of the research sonar system used for aquatic bioresourses monitoring. Single fishes behavior, vessel-carrier movement and pitching, sea surface state and sea bottom type are modeled in simulator. Fish reflecting properties and transmitting-receiving parameters of sonar are taken into consideration. Hydroacoustic signal envelope data array is formed in the output of simulator for each beam of multybeam receiving antenna of a sonar system.
Aquatic bioresourses monitoring, software simulator, sonar signal, calculation of fish, sonar system.
Today, the task of assessing aquatic biological resources (FBG) lies in the field of public interest, both when conducting marine and ocean research and monitoring aquaculture facilities [1]. In this regard, in the framework of the Federal target program "Development of civilian marine equipment" for 2009-2016. The enterprises of the Vector Marine Electronics, Ltd, ZAO NPP Nelaks and OAO NIIP conducted joint development of a scientific hydro-acoustic complex (NGAK) for counting and monitoring fish of valuable species living in the subsurface layer and in shallow water [2].
To solve the problem of detecting and reliably counting fish in the near-surface layer in a wide lane of view, with the help of NGAK, a fan of narrow beam reception directivity characteristics (HN) in the 2 × 90 degrees sector is formed (channels of the left and right sides, 128 rays in each channel ). The selection of useful signals against the background of noise, the localization of individual fish in space, the construction of tracks of fish movement and their calculation, the calculation of the distribution density of fish in the surveyed water space is carried out using software (software) of the control and display instrument (ISP).
At the software development stage of the ISP, it was necessary to have a tool that allows for complex software debugging without resorting to costly and long-term field testing of the equipment. The only solution to this problem, which allows such work in the laboratory, is the development of a signal simulator. In this regard, for successful implementation of the development and debugging of the software of the ISP, the specialists of KBME "Vector" developed a software simulator of hydroacoustic signals.
The signal simulator generates the following data:
- The array of amplitudes of the hydroacoustic signal envelope along each beam of the XN fan depending on the distance, including the following components [3]:
- probe pulse;
- echo signals from fish, (coordinates of fish location are randomly generated in a given space);
- echoes of the reverberation of the surface layer and volume reverberation;
- coherent and incoherent components of the bottom echo signal, depending on the topography of the bottom surface and its type;
- noise component depending on the speed of movement of the carrier vessel NGAK;
- the current values of the coordinates of the vessel, the values of the side and pitching, yaw, vertical and horizontal displacement of the carrier vessel NGAK.
The hardware part of the signal simulator consists of a system unit and two monitors for displaying the user interface of the signal simulator, the script editor and the three-dimensional display of the simulated underwater situation.
The screen form of the main window of the signal simulator is shown in Figure 1. An example of displaying the underwater situation of the three-dimensional visualization module is shown in Figure 2.
Figure 1 - Screen form of the main window of the signal simulator
The structure of the hydroacoustic signal simulator software, shown in Figure 3, includes the following software modules:
- script editor;
- system model;
- ship control module;
- module for calculating geometric and acoustic components;
- NMEA message generator;
- hydroacoustic signal generation module;
- visualization module.
Figure 2 - Display of underwater 3D visualization
Figure 3 - Structure of the signal simulator software
The system model performs the following functions:
1. Creates a kinematic model of ship motion with 6 degrees of freedom (uniform motion with an instantaneous response to the change in speed and course by the operator):
a) forward movement;
b) rolling;
c) pitching;
d) yaw;
e) vertical movement;
e) transverse-horizontal movement.
2. Forms a parallelepiped moving in space with a three-layer model of distribution of single fish in a water volume of 800 × 400 × 100 m3 (width × depth × length) with different density of fish distribution in the layers. In all layers, the fish are randomly distributed and move in the same direction with the same speed. When a vessel and fish approach each other, fish “run away” from the zone of fright with a given radius in radial directions.
Script Editor provides:
1. setting the parameters of movement and pitching of the vessel (course, speed, amplitude values of yaw, pitching and side pitching, vertical displacement);
2. setting parameters of the aquatic environment: a) the speed of sound, salinity and water temperature;
b) the power of volume reverberation;
c) the state of the sea surface;
d) the nature of the bottom;
e) the sailing area of the vessel (selected in accordance with the nautical charts or a flat bottom is set with a fixed depth);
3. parameters of the distribution of fish in water layers (distribution density, fish size);
4. setting the fright radius around the vessel;
5. setting the fish movement parameters (course, cruising speed, speed of throwing from the zone of fright, rest time, yaw parameters);
7. setting the time of movement of fish when frightened.
8. setting the parameters of the FGBO:
a) the range of the FGBO (up to 400 m);
b) the gain of the receiving path;
c) the type of temporal automatic gain control (VARU);
d) parameters of the directivity characteristic;
e) the position of sonar antennas relative to the center of mass of the vessel.
The ship control module controls the movement of the ship in a given simulation area and allows you to change the course and speed of the ship in real-time mode.
The module for generating NMEA messages generates an array of data containing information about the geographical position of the vessel, the parameters of the vessel’s pitching and the course of the vessel.
The module for calculating the geometric parameters and acoustic components calculates the values of the echo envelope along each beam of the XN fan FSBBO depending on the current spatial position of the XN fan relative to the surface, bottom, fish, and forms the resulting signal as the sum of the energies of the elementary echo components (probe pulse, reverberation of the surface layer , volume reverberation, noise component of a hydroacoustic signal, echo signals from fish, coherent and incoherent components of the bottom th reverb). After calculating the values of the echo envelope, depending on the distance, the signals are recalculated from the acoustic values to the electrical ones and the VAU is applied.
The signal conditioner of the FSBI structures the data obtained as a result of the calculation of acoustic components, and the data of the NMEA message generator in accordance with the FSGB and ISP data exchange protocol. Thus, at the entrance of the ISP there are simulated hydroacoustic signals from the FSBR, allowing for a comprehensive debugging of the algorithms and software of the ISP to calculate single fish.
The FSBBO signal simulator visualization module serves to control the generated source data and implements an indication of the amplitude sweep of the signal in the selected XN fan beam, an indication of the echogram of this beam and three-dimensional visualization of the underwater situation in accordance with the settings of the script editor and the results of modeling the movement of the vessel and fish movement.
Thanks to the developed simulator of hydroacoustic signals, the software of the control and indication instrument of the scientific hydroacoustic complex for calculating and monitoring fish of valuable breeds was debugged on the basis of a side-scan sonar with phase signal processing.
Bibliographic list
The aquaculture law passed the first reading. RIA Fishnews.ru. http://www.fishnews.ru/rubric/zakon-ob-akvakulture/3564
Dolgov A.N., Raskita M.A. Development of the structure of the SJC and requirements for the algorithms of secondary and tertiary signal processing for the detection and counting of single fish in the surface layer. - Proceedings of the X All-Russian Conference "Applied technologies of hydroacoustics and hydrophysics". - SPb .: Science, 2010. - p.134-136.
Dolgov A.N. Theory and practice of designing hydroacoustic equipment for simulators. –– Rostov n / D: Rosizdat, 2009. –400 p.
Information about authors
Dolgov Alexander Nikolaevich, Vector marine electronics, Ltd, This email address is being protected from spambots. You need JavaScript enabled to view it., This email address is being protected from spambots. You need JavaScript enabled to view it., Mendeleev, str. 6, Taganrog, 347913, Russia, tel./fax (8634) 333-900, director general, Ph.D.
Raskita Maxim Anatolievich, Vector marine electronics, Ltd, This email address is being protected from spambots. You need JavaScript enabled to view it., Mendeleev, str. 6, Taganrog, 347913, Russia, tel./fax (8634) 333-900, senior researcher, Ph.D.