|RWLT - Underwater acoustic tracking system
Underwater Acoustic Tracking System RWLT is designed for:
The RWLT system uses state-of-the-art digital broadband noise-immune hydroacoustic communication, and the applied signal is specially designed for difficult hydrological conditions, including those found in shallow waters.
The RWLT System is the Easiest to Use yet Accurate Subsea Tracking Solution. The system does not require any calibrations and integration: it is enough to place an autonomous pinger RWLT Pinger on an underwater object (ROV, AUV, diver, etc.), and four navigation buoys on the water surface RWLT GIB. This configuration allows you to monitor the movement of an underwater object in real time in 3D: absolute geographic coordinates + depth. A distinctive feature of the system is the ability to work with wireless diver’s telephones RedPhone-DX as a pinger, thus combining two-way voice communication and navigation.
The minimum composition of the system includes:
Navigation sonobuoy receiver
|RWLT RF Dongle
And, depending on the user task:
Wireless voice communication diver’s station
In this configuration, divers will be located at the moment they release the PTT button, i.e. completing the transmission of the voice message; the transmission of voice messages must take place in turn.
Depending on whether you are working with a pinger or tracking divers, you will need different versions of specialized software.
Download the necessary software in advance. Installation is not required - just unzip the contents of the archive to a location convenient for you.
Whether you are using underwater equipment such as wireless voice communication diving stations or a stand-alone pinger beacon, make sure that all equipment is fully charged before entering the water and charge all devices if necessary.
Particular attention should be paid to wireless voice communication diving stations and pinger beacons: in view of the fact that these devices have built-in power supplies based on LiFePO4, they have a very flat discharge characteristic and it is difficult to determine the state of charge of the built-in power source. Therefore, it is recommended to charge all devices no earlier than 1-2 days before use.
We use LiFePO4 based batteries as they are the most durable and withstand the maximum number of charge-discharge cycles compared to Li-ion and Li-Po batteries, and can also operate at low temperatures. temperatures.
Select the location where the system operator’s station will be located. Since the receiving antenna of the radio modem is located in this place, there must be a direct line of sight to each of the buoys from this place. For normal operation of the system, the operator’s console must be able to receive navigation data via radio from all four buoys. Place the radio modem at the highest possible height away from any bulky objects that shield radio waves (metal, reinforced concrete, etc.).
Connect the radio modem to the USB port of the PC. Launch the application appropriate for your task and press the 🔌 LINK button in the top toolbar - the application will start searching for a port for communication with the radio modem, which will be reflected in the status bar.
WARNING! Almost all known buoy failures are due to the user using a buoy with an unscrewed cap of the charging connector! Operation of buoys with an unscrewed cap of the connector is prohibited and may result in water ingress into the device. Failure of buoys due to water ingress through an open charging port is out of warranty!
The location of the controls and indications on the buoy cover is shown below.
|Location of controls and indications on the cover of the buoy
|1 - power switch, 2 - light indication lamps, 3 - charging connector (Radio antenna not shown)
The buoys in each set have different addresses from 1 to 4. When the buoy is turned on using toggle switch 1, the buoy reports its number in the set using indicator 2: the number of flashes corresponds to the buoy number.
After reporting its number, the buoy goes into operation mode. If the buoy’s battery is charged, the indicator will remain lit until the built-in GNSS receiver detects signals from the satellites of the global navigation satellite system. After that, it will flash 1 time in 4 seconds. The number of flashes in this case also corresponds to the number of the buoy in the set.
If the battery of the buoy is in a state where the charge is less than 20%, the indicator will flash 1 time per second. The number of flashes in this case also corresponds to the number of the buoy in the set.
If the user notices flashes 1 time per second, the buoy should be turned off and put on charge as soon as possible. Long-term operation with a discharged power supply is not permitted.
If the battery is in a state of critical discharge, then after reporting its number, the buoy will automatically turn off, in this case the indicator will also be off. The buoy must be immediately put on charge to avoid failure of the built-in power source.
If everything is done correctly, and the tops of the buoys have a good view of the celestial hemisphere, then after a while (usually no more than 1-2 minutes) you will be able to see the positions of the buoys in the main application window.
After that, you can place the buoys on the surface of the water.
If you need a significant amount of time to equip the buoys with anchor lines and place them on the surface of the water, you can turn off the buoys to save power and turn them on just before placing them on the water.
The buoys are placed in the water area on the surface of the water, their position is fixed with the help of anchors.
It is worth remembering that although the buoys have a slight positive buoyancy, they are not intended for direct attachment to an anchor line. To unload the buoy from the weight of the anchor rope, fenders (or floats) corresponding to the weight of the rope should be used.
The figure below1 shows the recommended scheme for installing a buoy on a body of water.
|Recommended buoy installation scheme
|1 - sonobuoy, 2 - extra weight2, 3 - float, 4 - anchor line, 5 - anchor
1 Images may vary slightly from actual product, as the manufacturer is constantly working to improve performance and make changes to the design. 2 The extra weight is only applied to the underloaded version.
The buoys should be located in a convex quadrilateral covering the entire proposed work area with a small margin. It is important to observe a few simple conditions for the effective operation of the system:
WARNING! Buoys are not underwater devices and are designed to operate on the surface of the water. Although the protection class implies a short-term overlap of the device with a wave, it is worth remembering that the built-in radio equipment (GNSS module and radio modem) cannot work in such conditions!
It is not recommended to throw buoys overboard. It is necessary to carefully lower them to the surface of the water, at the same time making sure that the length of the anchor rope is sufficient and its weight is perceived by the unloading fender, and the buoy is located vertically on the surface of the water and does not experience any additional loads.
Subsea equipment preparation varies for different system configurations:
The pinger beacon turns on automatically when it gets into the water (contacts for switching on from water are located on the battery pack). It should be remembered that immediately after switching on, the pinger beacon determines atmospheric pressure for 5 seconds for more accurate depth measurement. Therefore, it is recommended to submerge the battery pack first and wait 5 seconds before submerging the pinger beacon itself.
The pinger beacon must be fastened only to a special groove with a soft clamp in such a way as to exclude any uneven loading of the beacon body, excessive squeezing and shading/shielding of the beacon body. The figure below shows the basic requirements for mounting the acoustic part of the pinger beacon on the vessel:
|Requirements for mounting the acoustic part of the pinger beacon on the vessel
|It is not allowed to shield the spatial hemisphere or parts of the antenna located above the mounting groove; the pressure in the area under the fastening must be balanced with the external pressure
The performance of the pinger beacon is easy to check by lowering it into the water: when submerged more than 1 meter, it starts emitting a navigation signal with a period of 2 seconds.
We propose to start acquaintance with the application with its settings. The figure below shows a general view of the settings window, it can be opened by pressing the ‘⚙ SETTINGS’ button on the main toolbar of the main application window.
|Settings window controls
|1 - Checkbox for using an additional source of navigation data (GNSS receiver), 2 - Combo box of port speed of an additional source of navigation data, 3 - Checkbox for using the first buoy as an additional source of navigation data, 4 - List of map tile source servers, 5 - Button for reset the settings to default settings, 6 - Checkbox of automatic salinity selection (from the database), 7 - Salinity input field, 8 - Sound speed auto calculation flag, 9 - Sound speed input field, 10 - Water temperature input field, 11 - Number of points track to display, 12 - Radial error threshold input field, 13 - Drop-down list for selecting the size of map tiles, 14 - Buttons for accepting settings and canceling
The receiving radio modem is connected to the PC via the USB port. The application itself searches for the serial port and this does not require the user to set any settings.
In some situations it is convenient for the operator to see his own location on the map, this can be achieved in two ways: the first is to connect an additional GNSS receiver to the PC. In this case, the application needs to indicate that this method is being used by checking the check box 1 Use AUX GNSS. Also in this case, you need to specify the serial port speed at which the external GNSS receiver operates. The port itself does not need to be specified, the application will detect it itself.
If there is no external GNSS receiver, but the operator would like to see his own location on the map, you can use the second method: buoy #1 can be used as an external GNSS. This method has some limitations, for example, it is not always possible to locate the operator next to the buoy, the buoys provide a limited set of navigation information compared to an external GNSS receiver. If this method is applicable in the current task, then check the check box 3 Base 1 as AUX GNSS Source. In this case, the checkbox in box 1 will be automatically unchecked.
The application allows you to display tracks on top of the map, the tiles of which can be downloaded via the HTTPS protocol (this needs the Internet connection). Currently, the Open Street Maps service is supported. Field 4 Tile servers specifies server addresses, and field 13 Tile size specifies the size of tiles in pixels. To download tiles, the application needs access to the Internet.
Button 5 SET DEFAULTS allows you to reset the settings to the default state.
Check box 6 Auto salinity means that the application will try to determine the salinity from the database using the current geographic coordinates. The application contains a base of salinity of the surface of the world’s oceans with a step of 1 degree in latitude and longitude. Use this setting only in large bodies of water: seas and oceans. If you work in small inland waters, it is recommended to uncheck 6 and set the appropriate water salinity value in field 7 Salinity, PSU. In most cases, for inland fresh waters, a value of 0 PSU is adequate. If you have accurate data on the salinity of the body of water, or it can be measured directly, you can also enter it in field 7. The salinity value is used to calculate the speed of sound.
With the check box 7 Auto speed of sound unchecked and the corresponding field 9 Speed of sound, m/s allows you to set a known sound speed value. Use this option if you have a direct measurement, otherwise it is recommended to check the check box 7.
Field 10 Water temperature, °C allows to specify the relevant water temperature value. The water temperature is used in the calculation of the speed of sound, if the check box 9 Auto speed of sound is checked. If you are measuring water temperature, it is recommended to take samples some distance from the surface.
Field 11 Track points to show tells the application how many points (calculated positions) for each track should be displayed at the same time. This setting only affects the display. The application additionally stores all received points, which can then be saved.
Field 12 Radial error threshold, m specifies the radial error threshold (residual function values at the end of the navigation problem solution), above which the computed position is considered erroneous and discarded. It is recommended to set this value within 10 meters.
Buttons 14 OK and CANCEL are responsible for saving the settings and canceling the changes, respectively. After changing and saving the settings, the application will request a restart for the settings to take effect.
Consider now the main window of the application. Its general view with indication of the main controls is shown in the figure below.
|Basic elements of the main application window
|1 - Main toolbar, 2 - Map toolbar, 3 - Map panel, 4 - Additional information panel, 5 - Log panel, 6 - Divers list toolbar, 7 - Divers list, 8 - Track legend panel, 9 - Scale bar , 10 - Panel of switches for displayed parameters of divers, 11 - Status line
|Heading according to external GNSS
|0 .. 360
|Speed according to external GNSS
|Latitude according to external GNSS
|-90 .. 90
|Longitude according to external GNSS
|-180 .. 180
|Salinity (from settings or from database)
|0 .. 40
|Water temperature (from settings)
|-10 .. +40
|Sound speed (from settings or calculated)
|1300 .. 1600
|Built-in battery voltage of buoy 1
|10 .. 13
|Built-in battery voltage of buoy 2
|10 .. 13
|Built-in battery voltage of buoy 3
|10 .. 13
|Built-in battery voltage of buoy 4
|10 .. 13
|Signal level on buoy 1
|14 .. 36
|Signal level on buoy 2
|14 .. 36
|Signal level on buoy 3
|14 .. 36
|Signal level on buoy 4
|14 .. 36
|-90 .. 90
|-180 .. 180
|0 .. 99
|Geometric dilution of precision factor
|The quality of the relative position of the positioned object and reference points
|Distance to diver from external GNSS position
|0 .. 1500
|Direction (course) to the diver from the position according to external GNSS
|0 .. 360
|Reverse direction (course) from diver to external GNSS position
|0 .. 360
The most important parameters here are AZM, DST and RAZ: by azimuth and distance, the operator can always understand where this or that diver is located relative to him, and he can report the RAZ parameter to the diver via voice communication, so that he, adhering to this course, can perform homing task.
The display of various parameters is switched by the buttons on the panel (10). It should be understood that the parameters associated with the relative position of the diver and the surface point (range, forward and reverse course) can only be determined if there is an external source of navigation data - an external GNSS receiver that sets the system the location of the surface point of operator or when the setting is enabled Base 1 as AUX GNSS - when all parameters are determined relative to buoy #1.
Locating divers equipped with RedPhone-DX wireless voice communication stations is possible when the following conditions are met (assuming the stations are properly configured to work with the RWLT system, and navigation buoys are properly deployed):
It is necessary to remember the factors that reduce the efficiency of the system:
THIS SECTION IS UNDER DEVELOPMENT
Navigation buoys must be:
Pinger-beacon should be:
Diving Wireless Voice Stations Upon completion of work, it does not require any additional manipulations and turns off automatically in the air. Before packing in a shipping container, it is necessary to rinse and/or desalinate in fresh water, followed by wiping with an absorbent cloth and air drying for at least 30 minutes.
For additional and up-to-date information, refer to the Operating Instructions for RedPhone-DX Wireless Voice Diver Stations.
The manufacturer’s warranty covers only factory defects that appear during the operation of the device in accordance with this manual during the warranty period (2 years from the date of purchase).
The manufacturer guarantees free repair or replacement of faulty equipment from the delivery set that has failed due to a manufacturing defect.
The reasons for refusing free warranty service, free repair and replacement include:
ANY OF THE PARTS OF THE DELIVERY SET, INDIVIDUALLY AND AS A PART OF THE SYSTEM (hereinafter referred to as the “EQUIPMENT SUPPLIED”):
- NOT DEVELOPED AS MEANS OF RESCUE - NOT TESTED AS MEANS OF RESCUE - IS NOT MEANS OF RESCUE - THE MANUFACTURER DECLARES THAT THE EQUIPMENT SUPPLIED IS SAFE WHEN USE ACCORDING TO THESE INSTRUCTIONS AND IS NOT RESPONSIBLE FOR ANY CONSEQUENCES OF THE USE OF THE SUPPLIED EQUIPMENT
THE MANUFACTURER GUARANTEE THAT THE RWLT HYDRO-ACOUSTIC TRACKING SYSTEM (hereinafter referred to as the SYSTEM): - DESIGNED ONLY TO WORK WITH PINGER BEACONS OR DIVING COMMUNICATION STATIONS DESIGNED FOR JOINT OPERATION WITH THE SYSTEM - STRUCTURALLY CANNOT BE USED FOR TRACKING OBJECTS NOT EQUIPPED WITH PINGER BEACONS OR DIVING COMMUNICATION STATIONS NOT DESIGNED FOR JOINT WORK WITH THE SYSTEM - CONTAINS ONLY CIVIL AND UNLICENSED RADIO MODULES: GNSS RECEIVERS AND RADIOS THE ABOVE LIMITATIONS CANNOT BE REMOVED BY ANY MANIPULATION WITH THE SETTINGS AND/OR CONTROLS OF THE SYSTEM DEVICES AND/OR THE SOFTWARE INTENDED TO WORK WITH THE SYSTEM