TOPAS PS 18 shallow formation profiler

タイトルまたは説明

TOPAS PS 18 is a hull-mounted shallow formation profiler system with very high performance and adaptability. Its penetration is better than that of other surface towed buzzers, and its resolution is considerably higher. Using Ricker wave and non-envelope detection, the resolution can reach 0.1 ~ 0.2m. There is no ringing and thus silent masking near the reflector, especially near the sea floor.

The TOPAS PS 18 is designed to be used in sync with other echo detection systems, with launch intervals exceeding 2 seconds. The higher the speed, the stronger the water noise. The TOPAS PS 18 provides high quality shallow profile data at speeds of more than 10 knots and penetrations to depths of more than 200 m.

System highlight:
TOPAS PS 18 is a high frequency width, high sound source level, compact design with real-time processing capability.
 Bottom installation, working water depth from 20m to full ocean depth
 Narrow beam, wide band, with extremely high spatial resolution
 There is no obvious sidelobe, and clear shallow profile images can be obtained under harsh environmental conditions
 Penetration decreases linearly with range/water depth
 Operators can select transmit waveforms to optimize performance according to different application requirements
 Monopulse (Ricker), CW, and Chirp are standard waveforms. Interfaces to user-designed waveforms can be provided through files
 no ringing, making the thin layer reflect clearly
 has a complete interface for sensor signal , data processing, data display and data storage
 Roll, pitch, and heave beam stabilization
 Scanning beam steering (optional)
 receiver array with beamformers
 Slope function (from multi-beam systems)
 main frequency/resonant receiver (optional)
 off-line post-processing software
 Java software is portable
 Windows or Linux
 I/O and live data logging to SEG-Y format (rev 1)
 Raw data that can be distributed over a local area network (LAN) for simultaneous online processing in multiple locations
 Worldwide technical support

Main feature:
TOPAS PS 18 parametric sound source Shallow formation profiler is suitable for high-resolution shallow formation profiling and underwater target detection, operating water depths from 20m to full sea depth. The ship's bottom mount, with roll, pitch and heave beam stabilization, makes it an effective tool for a variety of fine, high-resolution surveys. Since no towing operation is required, survey ship speeds can reach more than 15 knots (depending on the ship noise level).

Thanks to the use of electronic beam steering technology, the operator can fully control the Angle of incidence of the beam on the seabed. As a result, the "footprint" position can be precisely positioned and the best penetration depth can be obtained. In addition, this technology makes three-dimensional shallow strata profiles a reality.

The TOPAS PS 18 Shallow Formation Profiler consists of three basic units:

 Transducers
− Eight modules have 128 channels, with each module having 16 channels
− Special transducer cable with connector, length 20 m

 Transmitting and receiving unit
− Switching linear power amplifier
− Built-in T/R-switch − Data acquisition circuit

 Operator workstation
− 19-inch LCD color monitor
− Keyboard
− Mouse
− 2 GB Memory (RAM)
− >250 GB Hard disk (Raid 10)
− Read and write DVD drives

 Complete system working software

 User Manual (Installation, operation, maintenance)

The information sources necessary for the TOPAS PS 18 to work include: ship motion sensors and GPS.

System working principle
The core of TOPAS PS 18 shallow formation profiler is the "parametric sound source". Parametric sound source is an acoustic emission device which utilizes the nonlinear characteristics of the medium and uses two high-frequency initial waves propagating in the same direction to obtain the difference frequency and the sum frequency wave in the far field. Parametric array sonar simultaneously transmits two high-frequency acoustic signals with similar frequencies f1 and f2 to the media under high pressure as the main frequency. When the acoustic wave propagates in the medium, it forms a difference frequency wave due to the nonlinear effect of the medium, and a series of secondary frequencies will be generated in the transmitting direction of the transducer. For example, the acoustic signal of f1, f2, f1+f2, F1-F2, 2f1, 2f2 can control the frequency of the difference wave by changing the two main frequencies. Because the frequencies of f1 and f2 are very close, the frequency of F1-F2 is very low, and it has a strong penetration of sedimentary layer, which can be used to detect the shallow formation structure of the seabed, and the reflected main frequency acoustic signal is used for accurate water depth measurement.

The main advantages of the TOPAS PS 18 parameter sound source are as follows:
 The difference frequency acoustic signal is very close to the beam Angle at high frequency, and there is almost no sidelobe, so the beam directivity is good and the resolution is high, avoiding the interference caused by the boundary inhomogeneity in the process of sediment detection and the complexity of signal processing. Controllable difference frequency acoustic signal can carry more sediment information. It is easy to classify and identify the objects buried in the sedimentary layer. The two high frequency waves emitted by TOPAS PS 18 are around 18 kHz, and the difference frequency of these two waves is used as its operating frequency.
 Because of the high frequency of the main frequency, the transducer can be made very small to achieve narrow beam shallow formation profile measurement. For example, a conventional transducer array with an operating frequency of 1 kHz has an area of about 225 m2 to obtain a beamwidth of 5°, while a parametric array transducer with the same beamwidth has an area of only 1.4m2. TOPAS PS 18 can not only compensate the ship's roll, pitch and heave, but also scan beam steering in the 80° scanning sector to obtain a shallow strip result, achieving a three-dimensional display of shallow strata profile measurement.
Operator workstation:
An operator workstation is a PC workstation used for system control, data acquisition and storage, data output, and data post-processing. The workstation is equipped with Windows operating system, Linux operating system is optional, and other systems supporting JAVA Virtual machine can also be used. Workstation with printer, plotter interface and serial interface. The digitally processed data is sent from the transmitting and receiving unit to the workstation through Ethernet cables. The MMI operation interface of the system work software is shown below.

Controls
All parameters related to the operation of the system can be entered in the operator workstation, including installation parameters, and important parameters can be password protected. System Settings for a particular application or an operator can be stored to a hard disk for future calls. Under normal circumstances, operator intervention in the system is limited. However, manual gain setting and range setting based on delay time is something the operator needs to do.

Although there is a wide selection range of all system operating parameters, working experience and practical application requirements will greatly simplify the selection process for operators. The working software provides two sets of default Settings, which can be called from the Settings menu (set-up). One set of parameters is used for high-resolution measurements (monopulse Ricker waves) and the other for high penetration measurements (chirp).

Information such as real-time data quality control, sound source level, processing results, ship attitude data and associated signal strength can be displayed on a color LCD monitor. The measurement results can be recorded to the hard disk, including: data digitally processed by the transmitting and receiving unit, beam pointing Angle, ship attitude data, position, time, date and all system working parameters required for post-processing. The data format is customized according to post-processing needs.

Emission performance
Primary frequency: 15 ~ 21 kHz
Primary beam Angle: 4°
Primary sound source level (Max) : 243 dB re µ*@********************equency: 0.5~6.0 kHz
Secondary beam Angle: < 5.5°
Secondary sound source level: 185~208 dB re µPa