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Main ❯ Underwater acoustic modems ❯ uWave devices family: Data brief

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support@unavlab.com		 uWave - family of underwater acoustic digital communication devices
Data brief

uWave devices family
Data brief

1. Devices of the family

The uWave family (pronounced: “mu-wave” or “you-wave”) is specifically designed for applications that are extremely sensitive to weight and size, and is currently represented by three devices:

A more detailed comparison of the characteristics of the family devices can be found in the uWave modems comparison tables.

All devices within the family are fully acoustically compatible and have a common NMEA-like protocol for interfacing.

2. Features of the acoustic protocol and code channels

The uWave acoustic transmission protocol implements code division multiple access (CDMA) and supports 20 isolating code channels. Any device of the uWave family can be configured with any code channels for reception and transmission.

An isolating code channel guarantees that data transmitted in one channel will not be received by a device receiving in any other code channel.

All devices of the uWave family can receive in only one code channel at a time.

2.1. Data rate

The standard mode for uWave devices is the mode with a data rate of 78 bit/s. This mode provides the maximum range and reliability of communication. It is in this mode that the largest number of code channels is available.

All devices of the uWave family support alternative modes providing data rates of 156, 314 and 634 bit/s. The higher the rate, the lower the noise immunity and, accordingly, the reliability and range of communication.

Different data rate modes are not compatible with each other. Switching the modem to another data rate mode is done by replacing its firmware.

3. Device operating modes

All devices of the family can operate in two modes; switching between them is performed by the user:

These modes determine how the modem perceives the data coming from the control system:

3.1. Transparent channel mode

In the transparent channel mode, the devices do not analyze the data coming from the control system and transmit it unchanged to the underwater acoustic channel, where it can be received by any device of the family that is receiving in the same code channel in which the transmission was made.

3.2. Command mode

In command mode, the devices analyze the data coming from the control system, and interaction with them is carried out within a very simple NMEA-like ASCII protocol.
In this mode, the devices can send short code requests to other devices: to request the depth, temperature and supply voltage of a remote modem, and to transmit 9 user commands.
Code requests have fixed lengths of the request and response signals, which allows the requesting system to determine the propagation time (and slant range) to the requested system.

The remote modem receives and processes a code request regardless of the mode it is in, which relieves the user system of the need to monitor the state of the remote modem.

The uWave USBL Modem devices make it possible to determine the horizontal angle of arrival of any incoming message from other devices of the uWave family. This includes user messages transmitted in transparent channel mode.

3.2.1. Packet mode

Packet mode allows transmitting data packets with guaranteed delivery (ALO - At-least-once) and delivery notification to the addressee. In packet mode, logical addressing of up to 254 subscribers is used on top of the code channels (255 is a broadcast address without notification and guaranteed delivery). Packet mode can be used only when the modem is in command mode.

4. Device equipment

The uWave, uWave Max and uWave Max OEM devices have a built-in supply voltage measurement module. The supply voltage of all devices of the family can be requested remotely by any other devices of the family.
Starting from firmware version 1.30, with command mode enabled by default, the SVC/CMD cable wire becomes a digital output. Strobing rectangular pulses synchronized with the moment the emission starts and the moment an incoming message is detected are transmitted to it. This option makes it possible to build navigation systems based on the modems.

The uWave, uWave Max and uWave USBL Modem devices have built-in depth/temperature sensors. Depth and temperature readings can be requested remotely by any device of the family.

The uWave USBL Modem devices additionally have built-in two-axis inclinometers (they measure the roll and pitch angles). The user can configure the output of this data in any ratios, or periodically, with a set period (from 0.5 to 60 seconds), or in tandem - when any data is received from remote devices. Inclinometer readings are available only locally.

All devices equipped with depth/temperature sensors, when switched on in air, automatically calibrate the pressure sensor, which eliminates the depth determination error associated with changes in atmospheric pressure and the zero drift of the sensor. To achieve the maximum accuracy possible for this technology, the device allows setting an appropriate value of the acceleration due to gravity for the place of work (for example, according to the WGS84 Gravity model, thereby eliminating the influence of its variation with geographic latitude).

The devices are designed for a maximum immersion depth of 300 meters.

4.1. Parameters available locally

Parameters that can be obtained from the device locally, i.e. when connected to it by cable.

  uWave uWave Max uWave Max OEM uWave USBL Modem
Pressure ✓ ✓ ✘ ✓
Temperature ✓ ✓ ✘ ✓
Depth ✓ ✓ ✘ ✓
Supply voltage ✓ ✓ ✓ ✘
Roll ✘ ✘ ✘ ✓
Pitch ✘ ✘ ✘ ✓

4.2. Parameters available remotely

Parameters that can be requested from the device remotely, i.e. via the underwater acoustic communication channel, using any other modem of the uWave family.

  uWave uWave Max uWave Max OEM uWave USBL Modem
Temperature ✓ ✓ ✘ ✓
Depth ✓ ✓ ✘ ✓
Supply voltage ✓ ✓ ✓ ✘

4.3. Ranges of measured values

Parameter Min Max Units
of measurement
Pressure 0 30000 mbar
Temperature -4 46 °C
Depth 0 300 m
Supply voltage 0 15 V
Roll -180 180 °
Pitch -180 180 °

4.4. Resolution when transmitting built-in sensor readings

Parameter Resolution
locally		 Resolution
remotely
Pressure 0.1 mbar -
Temperature 0.1 °C 0.1 °C
Depth 0.01 m 0.1 m
Supply voltage 0.1 V 0.1 V
Roll 0.1 ° -
Pitch 0.1 ° -

5. Application and integration

All devices of the uWave family interface with the user system via the 3.3 V UART physical interface and operate in transparent channel mode by default. This requires no additional integration or configuration.

To operate in command mode, a simple NMEA-like ASCII protocol is used.

Open-source examples for interfacing uWave devices are available on our GitHub:

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