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www.unavlab.com support@unavlab.com	Zima USBL - underwater acoustic navigation system User’s manual

Zima USBL
User’s manual

1. Introduction
2. System composition
- 2.1. Zima-B: Underwater acoustic direction-finding station
- 2.2. Zima-R: responder-beacon
3. ZHost host software
- 3.1. System requirements
- 3.2. Description of the ZHost software interface
4. Effective use of the Zima USBL navigation system
5. Troubleshooting
6. Obligations and disclaimer
- 6.1. Terms of replacement and free warranty service
- 6.2. Limitation of the manufacturer’s liability

1. Introduction

The underwater acoustic navigation system Zima is designed to determine, in real time, the horizontal angle and the distance to underwater objects equipped with Zima-R underwater acoustic responder-beacons. The responder-beacons (hereinafter, beacons) can be installed on remotely operated underwater vehicles (ROVs), human-occupied vehicles (HOVs), autonomous unmanned underwater vehicles (AUVs), as well as on recreational and technical divers (when the standalone version of the beacon is used).

The Zima navigation system is an ultra-short baseline (USBL) navigation system whose principle of operation is based on the use of a phased antenna array to determine the horizontal angle of arrival of the signal and on determining the distance to the beacon by the “request-response” method. A distinctive feature of this system is the so-called two-way navigation, a patented solution that makes it possible to determine the distance mutually, both at the base station and at the beacon, and also to transmit to the beacon the azimuth angle to the base station. The system also makes it possible to transmit remote control signals to the beacons and to receive telemetry data from the beacons.

2. System composition

2.1. Zima-B: Underwater acoustic direction-finding station

2.1.1. General information

The Zima-B underwater acoustic direction-finding station (hereinafter, the base station) is designed to transmit acoustic control signals to the beacons, to determine the signal propagation time to the beacons, to determine the horizontal angle of arrival of the beacons’ response signals, to transmit remote control commands and to receive telemetry information from the beacons by means of specialized underwater acoustic signals.


Figure 1 - Zima-B base station
external view

The base station is designed as a maintenance-free monoblock on a cable, potted in a high-strength polyurethane compound. The station has a phased antenna array, a transmitting antenna and a built-in depth/temperature sensor. As an additional option, the base station is supplied with a heading and position determination system. In the general case, the base station is mounted on a rigid vertical pole, taking into account the orientation of the antenna - the determined angles of arrival are given in the antenna coordinate system.


Figure 2 - Installation diagram of the Zima-B antenna
1-pole, 2-vessel, 3-water surface, 4-cable, 5-Zima-B antenna, 6-zero direction of the antenna

Figure 3 shows the dimensional drawing of the Zima-B base station. The base station has an entry for the power and data cable and an opening for the pressure/temperature sensor. Structurally, the base station is divided into the following parts: the cable entry (in the upper part of the station) and a mounting groove for securing the station with a clamp. Below it is the cylindrical surface of the transmitting piezoelectric element, under which the receiving phased antenna array is located. During installation, the surfaces of the transmitting element and of the receiving array must not be covered or shielded. For correct operation of the station, a direct line of sight is required between the working surfaces of the station and the transducer of the responder-beacon.


Figure 3 - Zima-B
dimensional drawing

In the standard configuration, Zima-B is supplied with a UART<->RS-422 interface converter and a cable 10 meters long, which is connected to the Bat&Link Box power supply and switching unit. Thus, through the switching unit, the station is connected to the host PC via the USB interface (serial port).

2.1.2. Technical specifications

PARAMETER	VALUE
DIMENSIONS (Ø x h)	64 x 128 mm
WEIGHT (dry)¹	0.44 kg
MAXIMUM DEPTH	40 m
NOMINAL DEPTH ACCURACY	0.1 m
MAXIMUM COMMUNICATION RANGE	3000 m
NOMINAL HORIZONTAL ANGLE OF ARRIVAL ACCURACY²	1°
MAXIMUM DEVICE TILT RELATIVE TO THE VERTICAL COMPENSATED BY THE BUILT-IN INCLINOMETER (ROLL/PITCH)	+/- 30°
OPERATING CONE (RELATIVE TO THE HORIZONTAL)²	+/-30°
BANDWIDTH	6 .. 18 kHz
BUILT-IN TEMPERATURE SENSOR ACCURACY	0.1°C
BIT ERROR RATE	10^-6
SNR²	-3 dB
MAXIMUM RELATIVE VELOCITY	+/- 2 m/s
STARTUP TIME	100 ms
OPERATING TEMPERATURE RANGE	-5 .. 50 °C
BATTERY LIFE³ WHEN SUPPLIED FROM BAT&LINK BOX	8 h
INTERFACE	USB (COM) 9600 bit/s
COMMUNICATION PROTOCOL	NMEA 0183 PZMA
CABLE LENGTH⁴	10 m
MULTIPLE ACCESS SCHEME (COMMANDS/SUBSCRIBERS)	32/23

¹ Excluding the weight of the converter and cable.
² The value was obtained in a laboratory static experiment, without taking into account the multipath propagation effect.
³ With the station operating at 1 request per 3 seconds.
⁴ Including the interface converter and extension cable up to the Bat&Link Box device. Optionally, the length can be increased up to 20 m.

2.1.3 Storage and maintenance

There are no special storage and maintenance requirements for the base station, with the exception of the following:

When used in salt and/or heavily polluted water, desalination (soaking and rinsing in fresh water) is necessary
The use of any organic solvents, strong acids, alkalis and other aggressive substances is not allowed
If necessary, the station can be washed in household soap solutions; keep the liquid away from the connector
Impact or significant static loads are not allowed
Strong bending of the cable (with a radius of less than 5 cm) is not allowed

2.2. Zima-R: responder-beacon

2.2.1. General information

The responder-beacon is designed as a maintenance-free monoblock on a cable, potted in a high-strength polyurethane compound. The appearance of the Zima-R responder-beacon is shown in Figure 4. Structurally, the beacon includes a cable entry, a mounting groove, a pressure sensor opening and a working surface. The pressure sensor opening and the working surfaces (the cylinder and the end face of the cylinder opposite the cable entry) must not be covered or shielded. For correct operation of acoustic communication, a direct line of sight is required between the base station and the responder-beacon.


Figure 4 - Zima-R
external view (standalone version)

2.2.2. Technical specifications

PARAMETER	VALUE
DIMENSIONS (Ø x h)	64 x 62 mm
WEIGHT (dry)¹	0.3 kg
MAXIMUM DEPTH	300 m
NOMINAL DEPTH ACCURACY	0.1 m
MAXIMUM COMMUNICATION RANGE	3000 m
BANDWIDTH	6 .. 18 kHz
BUILT-IN TEMPERATURE SENSOR ACCURACY	0.1°C
SUPPLY VOLTAGE	5 .. 12 V
DATA LINE VOLTAGE	0 .. 3.3 V
BIT ERROR RATE	10^-6
SNR²	-3 dB
MAXIMUM RELATIVE VELOCITY	+/- 2 m/s
STARTUP TIME	100 ms
OPERATING TEMPERATURE RANGE	-5 .. 50 °C
INTERFACE³	UART 9600 bit/s
COMMUNICATION PROTOCOL	NMEA 0183 PZMA
CABLE LENGTH³	0.5 m
MULTIPLE ACCESS SCHEME (COMMANDS/SUBSCRIBERS)	32/23
NOMINAL HORIZONTAL ANGLE DETERMINATION ACCURACY⁴	1°
NOMINAL DISTANCE DETERMINATION ACCURACY⁴	0.3 m

Additional parameters of the battery canister⁵

PARAMETER	VALUE
BUILT-IN BATTERY TYPE	Ni-MH
CAPACITY	2.9 A·h
NOMINAL VOLTAGE	12 V
NUMBER OF CELLS IN THE PACK	10 pcs
HOUSING MATERIAL	Delrin
OPERATING TEMPERATURE RANGE	-5 .. 50 °C

¹ Excluding the weight of the battery pack. Standard battery pack Ø50x165 mm, 0.58 kg, 2.9 A·h 12 V. Operating time with the standard battery pack in standby mode - up to 70 hours, with 1 transmission every 3 seconds - up to 8 hours.
² The value was obtained without taking into account the multipath propagation effect.
³ The value can be changed on request.
⁴ Obtained in laboratory conditions in a static experiment.
⁵ Standard delivery set, subject to change without notice.

2.2.3. Configuration options

The Zima-R beacon is a transceiver for underwater acoustic digital wideband communication and can be interfaced with the control system for both power and data. In this case, if the control system has a magnetic compass, it is possible to determine the distance and the relative bearing to the base station, as well as to receive remote control code commands from the base station. In the standalone version, the beacon is supplied with a battery canister, as shown in Figure 4. In this case it is fully autonomous and does not need to be interfaced with the carrier. In the OEM version, the beacon is supplied as a set of electronic boards to be installed by the user in their own one-atmosphere (normobaric) housing. The beacon is supplied with a deep-water underwater acoustic transducer. Routing the transducer cable into the one-atmosphere housing and connecting it to the beacon electronics is, in this case, done by the user.

2.2.4. Working with the device (standalone version)

In the standalone version, the beacon is fully autonomous. For operation, it must be fixed on the carrier in such a way that the working surfaces of the monoblock (the cylindrical surface and the end face) are not covered by the mounting elements (the special groove must be used for mounting) and are not shielded by various structural elements of the carrier. To switch on the responder-beacon, connect it to the battery pack using the connector, as shown in Figure 5.


Figure 5 - Connecting the responder-beacon to the battery pack

In this version, the beacon is supplied with a 10-cell nickel-metal hydride battery pack. The one-atmosphere (normobaric) housing (canister) has a lid with a double seal and a four-start thread, which allows the canister lid to be closed in 3/4 of a turn. Before immersion in water, make sure that the canister lid is screwed on hand-tight. After the beacon connector is connected to the battery pack, the device calibrates the atmospheric pressure during the first ten seconds; therefore, do not apply any pressure (negative or positive) other than atmospheric to it during the first ten seconds after the device is switched on - this will result in incorrect depth measurement by the responder-beacon. In the standalone version, the Tx and Rx wires of the beacon cable are shorted (see Figure 6). This automatically disables the UART module to save power.

CAUTION! Zima-R devices in the standalone version manufactured after October 2020 indicate that they are operational by emitting a signal 1 second after power is applied.


Figure 6a - Zima-R
dimensional drawing


Figure 6b - Zima-R
Cable wire assignment

2.2.5. Working with the device (integrated version)

When interfaced with the carrier for both power and data, the beacon transmits to the carrier the distance to the base station and the azimuth to the beacon (only when a magnetic compass is connected to the base station). In addition, in this case the base station can transmit up to 28 code commands, and the responder-beacon reports them to the carrier in accordance with the communication protocol.

2.2.6. Storage and maintenance

The responder-beacon does not require any special maintenance procedures, except for desalination and rinsing in running fresh water after use in salt and/or contaminated water. Note that the use of any lubricants or solvents, aggressive detergents, etc. to remove contamination from the responder-beacon and its cable is not allowed.

If the beacon is used in the standalone version, additional requirements apply and maintenance measures are prescribed for the battery pack and the canister. In particular:

long-term (more than one day) storage of the battery pack while it is connected to the beacon is not allowed;
long-term storage of the battery pack without scheduled recharging (once a month) is not recommended;
if contaminated, the O-rings and the thread of the battery canister must be cleaned with water, a soft brush and a soap solution, followed by rinsing in running fresh water and lubricating the O-rings with silicone grease;
the canister is stored with the lid closed;
when the device is used in salt and/or contaminated water, it must be desalinated in running fresh water after the work is finished.

3. ZHost host software

3.1. System requirements

The specialized software ZHost (hereinafter, the software) runs under the MS Windows operating system, versions 7, 8 and 10. A monitor with a resolution of at least 1024x768 pixels and a mouse or touchpad are recommended. The software is portable, is distributed as a zip archive (Download the latest version) and does not require any installation other than unpacking it on the user’s PC.

The executable file ZHost.exe, the settings file ZHost.settings and the required libraries are located in the root directory of the application. Localization resources are located in subdirectories corresponding to the localization language (e.g. \ru, \ru-RU, etc.). While running, the application keeps log files. The logs are stored in the \LOG subdirectory, which contains subdirectories named with the current date (for example, \LOG\2020-01-21), which contain .log files with names corresponding to the file creation time (HH-MM-SS). A new log file is created each time the application starts. The log files are in text format and contain all data exchanged between the host software and the connected devices, as well as all errors that occur during the operation of the software.

When the AUTOSNAPSHOT function is enabled, screenshots of the application window are saved in the \SNAPSHOTS directory, which also contains subdirectories named with the creation date; the window screenshot files are named with the current time (HH-MM-SS) and are in PNG (Portable Network Graphics) format.

Since the connection to the base station is made through UART/RS-232/RS-422 to USB interface converters, additional drivers for the specific converter may be required.

3.2. Description of the ZHost software interface

The general view of the application window is shown in Figure 7. It consists of a toolbar (menu) located at the top of the window and a status panel located at the bottom of the window; on the left is the screen that displays the relative position of the responder-beacons (PPI), and on the right is a tree structure containing the properties of the beacons in use (RESPONDERS).
The toolbar consists of an upper subpanel (CONNECTION, STATION, etc.) and a lower subpanel (AUTOQUERY, AUTOSNAPSHOT).


Figure 7 - ZHost host software
main window view during operation

The “CONNECTION” menu item is used to open and close connections on the configured serial ports. These include the port through which information is exchanged with the base station, the AUX ports through which the software can receive (with the appropriate settings) navigation data from a GNSS + GNSS compass or a GNSS + magnetic compass, and also the GNSS emulation port for one of the responder-beacons.

When the “CONNECTION” menu item is clicked, the application tries to open connections on the serial ports according to the specified settings. If no additional navigation data providers (GNSS, compass) are specified and the system operates in relative coordinates, an attempt is made to open the port for communication with the base station. If one or both AUX ports and the GNSS emulation output port are enabled in the settings, the software will try to open them as well.

If the ports are opened successfully, the “CONNECTION” menu item becomes highlighted, and clicking it again closes the connections.

The “STATION” menu item becomes active only after the connection to the base station is open and the device information has been successfully received from it. The item contains the following subitems:

“VIEW INFO” to open a dialog box containing information about the connected base station (device serial number, firmware version, etc.).
“DEPTH CALIBRATION” to open the dialog box for setting the actual depth of the base station.

This menu item becomes active only after the connection to the base station is open and the device information has been successfully received from it, and the “AUTOQUERY” function is not active. The item contains the following subitems:

“SEND A COMMAND…“ to open the remote command dialog box, in which the user can select the address of the responder-beacon to which a user command is to be sent, and the command identifier.
“CHANGE ADDRESS…“ to open the dialog box for changing the address of a remote responder-beacon. In the dialog box, specify the current address of the beacon whose address is to be changed, and the new address. Be careful when using this function. It is intended only for setting beacon addresses before immersion.
“SET CURRENT DEPTH AS ZERO” to open the atmospheric pressure calibration dialog box. In the dialog box, specify the address of the beacon. On receiving the command to calibrate the atmospheric pressure, the responder-beacon will take the current pressure readings of its built-in sensor as atmospheric. Be careful when using this function. It is intended only for setting up beacons before immersion.

The “LOG” menu item contains functions for working with the application log files and contains the following subitems:

“VIEW”. Selecting this subitem opens the current application log file.
“ANALYZE…“. Selecting this subitem displays the dialog for selecting the file to be analyzed. The log file analysis function makes it possible to quickly restore the course of the system’s operation, for example, to restore the tracks of the vessel and/or of the responder-beacons in case of its loss.
“ANALYZE CURRENT”. This function acts like the “ANALYZE…“ function, except that the current log file is selected as the file to be analyzed.
“RESTART CURRENT”. When this subitem is activated, the contents of the current log file are deleted and logging continues.
“CLEAR ALL”. This menu subitem is intended to delete all application logs from the LOG\ directory. Caution! The data from the log files will be lost irretrievably!

The “TRACK” menu item contains functions for working with the tracks generated by the software and contains the following subitems:

“SAVE AS…“ is used to open the dialog box for selecting the file name and format for saving the tracks. The function becomes active only if there is unsaved geographic data in the system. The software supports exporting tracks to the Keyhole Markup Language (KML) and Comma-separated values (CSV) formats.
“CLEAR”. This subitem is used to delete all geographic data accumulated by the software during the current session. Use this function with caution!

The “SETTINGS” menu item is active only when the connection is closed and is used to open the dialog box for changing the software settings.

The settings are saved in the root directory of the application. Keep in mind that, for the changed and saved settings to be used by the application, it must be restarted. If the settings are saved successfully, the software displays the corresponding prompt to the user.

For convenience, the settings in the dialog box are arranged in groups, each group on a separate tab. The “SET DEFAULTS” button is used to restore the default settings.
The “OK” button, used to accept the settings, is active only when the user has entered consistent data (for example, when the AUX ports are enabled, the names of all enabled ports must not coincide with each other).

The “CONNECTION” tab contains the settings of the connection ports. Its appearance is shown in Figure 8.


Figure 8 - Settings window
“CONNECTION” tab

The “ZMA Port” group is always active and is responsible for the settings of the connection to the Zima-B base station. In commercially produced devices, only a baud rate of 9600 bit/s is supported.

The other groups, “AUX1 Port”, “AUX2 Port” and “Output Port”, become active only if the corresponding checkbox is selected.

If the Zima USBL system is used with a GNSS receiver with an azimuth determination function, use only one of the AUX ports, through which the data from this receiver enter the system
If the Zima USBL system is used with a standard GNSS receiver and the direction data are supplied by a magnetic compass, both AUX ports must be used: the GNSS receiver is connected to one of them and the magnetic compass to the other.

If the “Save AUX input to log” checkbox is not selected, the data coming from the AUX ports will not be saved to the log file.

If the system operates in absolute coordinates (i.e., it receives data on the geographic location of the base station and its orientation relative to the cardinal directions) and the absolute geographic coordinates of the responder-beacons are calculated, it becomes possible to emulate GNSS RMC and GGA sentences based on the geographic position of the beacon and transmit them to the output port.

This can be, for example, a virtual COM port, to the other end of which mapping software (for example, SAS.Planet) can be connected to display the location of the beacon on the map in real time. To enable this function, select the “Use output port” checkbox, set the required port settings, and also specify the address of the beacon whose coordinates will be used to emulate the GNSS data.

If the “Save separately” checkbox is selected, the data transmitted to the output port will be saved in a separate log.

The “COMMON” tab contains the settings of the addresses of the beacons in use and some physical parameters. Its appearance is shown in Figure 9.


Figure 9 - Settings window
“COMMON” tab

The “Responders in use” group contains the list of all possible beacon addresses. The system will automatically poll the beacons whose addresses are checked in this list.

The “Timings” group contains the settings:

the data obsolescence threshold (in seconds). If a value has not been updated for longer than the specified time interval, the symbols OBS (Obsolete) are displayed in parentheses next to it, indicating to the operator that this particular parameter (for example, the water temperature or the beacon supply voltage) has not been updated for a long time
Max distance. This parameter tells the system the maximum distance at which the responder-beacon may be located. This parameter determines how long the base station will wait for a beacon response. If for some reason the station does not receive the response signal of the beacon, it waits for it for a certain time, called the timeout. It is advisable to set the smallest possible value based on the requirements of the task, in order to limit the idle time of the system while it waits for a missed beacon response.

The “Salinity” group makes it possible to set the water salinity value (in PSU) either directly or by selecting it from the world ocean salinity database (by opening the salinity selection dialog via the ”. . .” link). It is not recommended to take the salinity from the database for small inland water bodies: rivers, lakes, ponds, etc. In this case, if the exact value is not known, set the salinity to zero (fresh water). The salinity value is used by the system for more accurate determination of the depth and of the speed of sound.

The “Sound speed autocalculation” checkbox and the corresponding group controlled by it determine where the system takes the speed of sound in water from. If this value is known directly from a measurement, disable the automatic calculation function and specify the value directly. In all other cases the checkbox must be selected. In this case, the system calculates the speed of sound from the pressure, temperature and salinity. As a rule, the calculated value is in good agreement with the actual one.

The “Misc.” group contains:

The “Rough depth (faster)” checkbox. If this function is enabled, the beacon transmits the depth with a lower resolution (~40 cm), but the depth is transmitted in a single “request-response” transaction, and the simultaneous navigation function (sending to the beacon the reverse azimuth to the base station and measuring by the beacon the distance to the base station) is unavailable. If the simultaneous navigation function is not required (for example, if the beacon is used in the standalone version) and an accuracy of 40 cm in depth is sufficient, select this checkbox.
The “Antenna heading is fixed” checkbox is intended for the situation when the system operates in relative coordinates and the base station is fixed motionless (for example, on a pier or another stationary facility of the port infrastructure) so that its horizontal axis points to the north. In this mode, the reverse azimuth can be transmitted to the responder-beacons without the need for a GNSS receiver and a compass.

The “MISC.” tab contains the settings of the orientation of the base station relative to the position reference point (the GNSS antenna) and the zero direction of the compass. Its appearance is shown in Figure 10.


Figure 10 - Settings window
“MISC.” tab

The “ΔX” and “ΔY” parameters (in meters) define the location of the base station in a rectangular coordinate system associated with the antenna of the GNSS receiver (according to the figure)
The “δ“ parameter (in degrees) sets the rotation of the zero of the base station antenna relative to the zero of the magnetic or GNSS compass

This menu item controls the “AUTOQUERY” mode. When this mode is enabled, the software automatically polls the responder-beacons at the highest possible rate according to the “Responders in use” list on the “COMMON” tab of the application settings window. The “AUTOQUERY” mode is the main operating mode of the system and should be disabled only when navigation data is not required or when a user command must be sent to one or more beacons (this function is unavailable while the “AUTOQUERY” mode is enabled).

If this function is enabled, the software automatically saves an image of the main window when the data is updated. The files are located in the “\SNAPSHOTS\YYYY-DD-MM" directory, where “YYYY-DD-MM” is the current date. Each file is named according to the current time in the format “HH-MM-SS” and is in the Portable Network Graphics (*.png) format.

3.2.2 PPI panel

On this panel (see Fig. 7), the position of the base station is displayed in the center in the form of a yellow arrow, which points from bottom to top when working in relative coordinates and changes its orientation when heading data is available. In the latter case, the symbol “N” (North) is displayed at the top of the dial. The “PPI” panel displays the position of the beacons relative to the base station. The beacons are displayed as circles with the beacon address inside. When a timeout occurs (the waiting interval for the beacon response is exceeded), the corresponding beacons are displayed with a dashed line.

The current state of the base station is displayed in the upper left corner:

TRX: transceiver state (TX - transmitting, RX - waiting for a response, READY - ready for requests)
DPT: depth (distance from the water surface) of the base station according to the readings of the built-in pressure sensor
TMP: water temperature according to the readings of the built-in temperature sensor

Additional data received by the system via the AUX ports is displayed in the lower left corner:

LAT, LON: geographic latitude and longitude (from RMC sentences)
AZM: azimuth angle (from HDG or HDT sentences)
SPD: speed (from VTG sentences)
VTG: course over ground (from VTG sentences)

3.2.3 RESPONDERS panel

This panel displays the data of the responder-beacons as a tree structure, where the first-level nodes denote the beacons (“RESPONDER #XX”), each of which has a set of nodes denoting various parameters and characteristics of the beacons in the form Parameter identifier: Value. Below is a list of possible parameter identifiers and their descriptions.

Parameter identifier	Units	Description	Source
MSR	dB	Mean lobe-to-sidepeak ratio. Reception quality characteristic. Reception threshold 14, values above 20 - good reception	Determined by the base station when receiving a beacon response
DPL	Hz	Doppler shift of the carrier frequency	Determined by the base station when receiving a beacon response
AZM	°	Azimuth to the beacon	Determined by the base station when receiving a beacon response
DST	m	Slant range to the beacon	Determined by the base station when receiving a beacon response
STY	PSU	Salinity value that was set for the beacon	From the beacon response confirming that the parameter was set
LQR	-	Result of the last service request	Determined by the logic of the ZHost software
TMP	°C	Ambient temperature (water temperature)	From the beacon response, according to the data of the built-in sensor of the beacon
BAT	V	Beacon supply voltage	From the beacon response, as the result of a direct measurement
LAT	°	Geographic latitude of the beacon	Determined by the logic of the ZHost software
LON	°	Geographic longitude of the beacon	Determined by the logic of the ZHost software
DPT	m	Depth (distance from the water surface) of the beacon	From the beacon response, according to the data of the built-in depth sensor of the beacon
DSTP	m	Projection of the slant range onto the water surface	Determined by the logic of the ZHost software

To the right of each value, the age of the data is displayed - the time that has passed since the parameter value was last updated. The age is displayed only if it exceeds 7 seconds.

3.2.3 Status panel

This panel is located at the bottom of the window and displays the state of the corresponding devices:

ZMA: base station
GNSS: geographic position
HDG: azimuth data source

The Zima USBL system is an underwater acoustic ultra-short baseline system that determines the relative location of the responder-beacons from the propagation time of the acoustic signal in water and the angle of arrival of the response signal of the responder-beacons.
Therefore, its effective use requires compliance with the following conditions:

ensuring a stable position of the base station during operation; This condition is ensured by reliably securing the base station on a vertical pole, taking into account the direction of the zero of the direction-finding antenna. Angular deviations of the vertical axis of the station from the vertical, as well as deviations and oscillations of its zero, adversely affect the accuracy of determining the angle of arrival of the response signal;
ensuring a direct line of sight between the base station and the responder-beacon; Since the distance to the responder-beacon is determined from the propagation time of the underwater acoustic signal in water, any obstacles in the signal path strongly distort the measured propagation time and, consequently, the determined distance to the responder-beacon; obstacles include both natural ones, associated with the bottom relief and/or the shore profile, and artificial ones - piers, quay walls, deep-draft vessels, bridge supports and other engineering structures;
the working surfaces must be free of various contaminants (silt, dirt, algae, etc.);

Owing to the specifics of the propagation of sound vibrations in the aquatic environment, the base station should not be located at a depth of less than 2–3 meters and should be at least 1.5 meters from the lowest point of the keel for small boats and not less than 2–3 meters for large boats.

The antenna array of the base station is designed to determine the horizontal angle of arrival of the signal of the responder-beacons, so keep in mind that with such a mutual arrangement of the antenna and the responder-beacon in which they are located practically on the same vertical axis, the accuracy of determining the location of the responder will be minimal. A good mutual arrangement of the antenna and the responder-beacon is one in which the projection of the slant range onto the water surface significantly exceeds its projection onto the vertical axis. The working vertical angles of the Zima-B base station are the angles of +/- 30° from the horizontal plane passing through the antenna array of the base station. This is illustrated in Figure 11:


Figure 11 - Geometric limitations of Zima-B
1 - working zone (+/- 30°), 2 - accuracy reduction zone (30 .. 45°), 3 - shadow zone ( > 45°), 4 - direction-finding antenna. The deviation is measured from the horizontal plane passing through the center of the antenna array

5. Troubleshooting

No.	Symptoms	Possible cause	Remedy
1	Unable to establish a connection between ZHost and Zima-B (error “COM port access denied”)	A peculiarity of the operation of the RS422-USB converter drivers in Win8-10 systems	1. Disconnect power from the Zima-B station 2. Unplug the USB connector 3. Close the ZHost application 4. Plug in the USB connector 5. Launch the ZHost application 6. Click the CONNECTION button in ZHost 7. Apply power to the Zima-B station
2	The station emits a request signal, but the beacon does not respond	Hydrological conditions prevent stable communication	Check that the beacon works at a short distance (0.5–10 meters) with a direct line of sight
		The power connector on the beacon is not connected	Plug in the connector
		The battery pack of the beacon is discharged	Charge or replace the battery pack
		The requested beacon address does not match its actual address	In the ZHost settings, select all available addresses; the station will go through all of them in turn, and thus the beacon address will be determined
		The signal may not be emitted in full because the station does not have enough power	This is possible when the station is powered from power supplies that have a current limit. For normal operation in the transmit mode, the station needs about 3 A
3	There is no communication with the Zima-B station; the port is open, but the station does not transmit data	No power reaches the station	Check the power supply and the connecting cables
		The station is faulty	Replace the station
4	The determined angle of arrival has a static error	The zero directions of the station and of the compass (or of the longitudinal axis of the vessel) are at an angle to each other - the station is rotated in the clamp	Align the zero direction of the station with the longitudinal axis of the vessel and/or the zero direction of the compass, and prevent accidental rotation of the antenna in the clamp
5	The system works, the beacon responds, but the absolute location of the beacon is not calculated (with an external GNSS receiver, compass or GNSS compass connected)	The data on the geographic position and heading of the vessel is not updated	Check that the GNSS receiver and the magnetic/GNSS compass are working, and check the connecting cables and the port settings

6. Obligations and disclaimer

6.1 Terms of replacement and free warranty service

The manufacturer’s warranty covers only factory defects that become apparent during 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 factory defect.

Grounds for refusing free warranty service, free repair and replacement include:

any mechanical damage to the equipment from the delivery set, including damage to the insulation of wires and cables;
any damage caused by exposure to moisture and contamination as a result of improper operation of the equipment from the delivery set;
any electrical damage caused by the use of accessories not included in the delivery set; accessories supplied by the manufacturer or its representative to replace faulty or lost ones are not considered to be outside the delivery set;
any signs of unauthorized repair and/or opening of the equipment from the delivery set.

6.2 Limitation of the manufacturer’s liability

ANY OF THE PARTS OF THE DELIVERY SET, INDIVIDUALLY AND AS PART OF THE SYSTEM, HEREINAFTER REFERRED TO AS THE “SUPPLIED EQUIPMENT”:

- WAS NOT DESIGNED AS RESCUE EQUIPMENT
- WAS NOT TESTED AS RESCUE EQUIPMENT
- IS NOT RESCUE EQUIPMENT
- THE MANUFACTURER DECLARES THAT THE SUPPLIED EQUIPMENT IS SAFE WHEN OPERATED IN ACCORDANCE WITH THESE INSTRUCTIONS, AND THE MANUFACTURER IS NOT RESPONSIBLE FOR ANY CONSEQUENCES OF THE USE OF THE SUPPLIED EQUIPMENT

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Zima USBL
User’s manual

Contents

1. Introduction

2. System composition