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Fast Underwater
Wireless Communication

Trusted by World-Leading Companies


LUMA™ is a line of optical modems that are compact, power efficient, and operate from the splash zones down to 12km depth with a communication speed of up to 10 Mbit/s and the range of up to 75 meters.

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Plug & Play

LUMA is designed with flexibility in mind. In its base configuration, it is a transparent link between your legacy systems, making it very easy to integrate. Plug&Play is not just marketing language when it comes to LUMA.

Fast. Faster…

LUMA modems are lightning fast. They can send data at up to 10 Mbit/s bandwidth enabling truly HD-quality video transfer wirelessly through water in real time.

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LUMA penetrates air to water barrier with no effort, making it a great alternative to cables in extremely unforgiving splash zone conditions. It can wirelessly stream underwater data to the satellite-connected ground systems.

From Splash Zones...

...To 12km Depth

LUMA offers unparalleled connectivity and can be a vital agent for real-time monitoring of structures in digital twin systems. Its unique construction results in extreme portability even at the planet's deepest point - the Mariana Trench. 

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Unmatched Power Efficiency

Our most advanced LUMA modem will consume 1500 times less energy than a fastest acoustic modem on the market per bit of data. It makes LUMA the best alternative for data transfers on battery-powered sensors.


With the small size, low power consumption and high data rates, LUMA opens up new connectivity possibilities underwater in many industries where submerged assets need to be monitored or inspected in real time.

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LUMA enables wireless HD video connection for the resident autonomous underwater vehicles (AUVs) so that the pilots could take control over their AUVs remotely near the assets.

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LUMA will wirelessly transfer high volume of data in a variety of subsea applications during construction, inspection, monitoring and repairs in the offshore energy sector.

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In the science & research sector it will serve as a regular environmental data uplink from an ADCP, a camera or other sensors on the sea floor.


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Ultra-compact and low weight

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Low latency

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Minimal multi-path distortion

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High tolerance to ambient light


Fully transparent link

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Ultra-low power sleep mode with optical wake-up with less than 10mW

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Four transmission power levels: 2 – 5 W

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Ad-hoc networking (on request)

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6000m depth rated

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High speed data transfer up to 10Mbit/s

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Wide supply voltage range

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120-degree beam cone

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Infinitely programmable
for mesh networks (on request)


Plug & play ethernet interface





LUMA X-UV is an optical communication modem specifically designed for the environments with other light sources present around. It offers HD-quality video and 4K image transfer in real-time in a compact titanium housing, even in the presence of ROV lights or other light pollution.


Comparison table

Comparsion table

Use cases

Use Cases


For more videos, please check our YouTube channel!

  • YouTube
  • Can other light sources interfere with the data transmission?
    Yes, any light source can be a possible source of interference. The level of interference however strongly depends on the type and brightness of the light source. Typically, constant light sources (such as sunlight, incandescent lights) cause much less (if any) interference than pulsed light sources (dimmed LEDs, fluorescent tubes with an electronic ballast).
  • What has been done to make the LUMA modem tolerant to ambient light?
    We have worked diligently to achieve the widest possible dynamic range with our optical modems, making them as tolerant as possible to ambient light conditions. While some competing products may only work at depths of 150 meters and below in near darkness, our modems are typically more tolerant to the ambient light. LUMA X UV is the best choice in the environment with a lot of ambient light pollution.
  • Why is it important to protect the modem from sunlight in shallow water?
    The human eye adapts to light on an exponential scale, making differences in light levels less obvious to us. However, for a photosensor like the modem's receiver, even small variations in light can have a significant impact. The best performance for the LUMA modems is achieved at light levels of 1 lux and below, which is quite dark. For comparison, a well-lit office or a trade show floor can have light levels around 500 lux, while direct sunlight can reach up to 40,000 lux, which is approximately 1 million times stronger than the modem's signal. Deploying LUMA modems under direct sunlight, for testing or for data transfer, is not recommended.
  • Are there specific strategies for one-way communication using the LUMA X UV modem in sunlight?
    For one-way communication, such as a camera streaming video via UDP, it can help to position the receiving modem looking down and the transmitting modem looking up. This arrangement reduces the receiving side's exposure to sun and sky. Additionally, placing a plate behind the receiving modem can create a "shadow zone" to further reduce back-scattered sunlight around the modem.
  • What is the recommendation for using the LUMA optical modem in shallow water with sunlight?
    In shallow water with sunlight, we recommend using LUMA X UV, specifically designed for more challenging ambient light conditions as it operates in the UV spectrum. However, while LUMA X UV is robust against visible artificial light sources like halogen and LED lights, natural sunlight still contains a significant amount of UV light. Adding a sunshield to keep the modem receiver in shadow as much as possible would measurably improve the performance. This can be achieved by mounting a larger plate above the modem to block the sky's view or by placing a tube around the LUMA modem, extending it 5-10 cm beyond the front lens. Depending on conditions such as depth, turbidity, and light scattering, this can extend the effective communication range of the modem.
  • How does turbidity affect LUMA's performance?
    The maximum range (and speed) specified in the data sheets of all LUMA modems does assume clear water, as it is typically encountered in deeper waters. Turbidity does decrease the maximum range at which LUMA modems can operate. In turbid waters the maximum communication range for LUMA X and LUMA 500ER is about 3 times the visibility ("Secchi Depth"). A more detailed analysis for LUMA X is available upon request.
  • Do I need a separate unit for transmitting and receiving data?
    No, all LUMA devices are transceivers and can send and receive data (half-duplex).
  • Can different LUMA models communicate between each other? I.e. can a LUMA X modem communicate with a LUMA 500 or LUMA 100?
    No, LUMA modems can typically not communicate between each other as typically one of the following differs between two different models: wavelength, speed, modulation, transmission range (sensitivity).
  • What type of data protocol is implemented in the LUMA devices to ensure error-free packet delivery?
    A number of configurable forward error correction schemes, which increase the reliability of the communication channel, are implemented. Faulty packages are automatically rejected on the receiving side using a checksum which is automatically added on the sending side. In order to maximize the transparency and versatility of the LUMA optical communication nodes, no additional protocol layers (such as TCP) which would ensure data delivery through resending, are implemented.
  • Which communication protocol is used to talk to LUMA modems?
    LUMA modems do not have a communication protocol "per se" like acoustic modems do, as they act as a transparent link replacement for a serial cable (LUMA 100/250LP/500ER) or an Ethernet cable (LUMA X/X-UV). More specifically LUMA X modems act as a transparent link to end devices, similar to a network switch or a wifi router. The LUMA X modem works in the link layer of the IP stack, which means it will forward any Ethernet packet that it sees without the need for an additional protocol. LUMA 100/250LP/500ER modems act like a wireless serial cable. While the modem internally packetizes the continuous serial stream adds a checksum, possibly does forward error correction, do the devices on both ends it looks like the continuous serial stream from a cable. There is however an API for LUMA X/X-UV which allows the user to obtain modem status information and to set parameters. This API is documented in the manual for the LUMA X/X-UV modem.
  • Is there any Software Development Kit? Can we use open source Python programming for communication?
    All LUMA modems provide a fully transparent connection so the devices on both ends are usually not even aware of the modems in between them. So like an Ethernet cable or a serial cable the modems are agnostic to the data sent across them and the operating system of the hosts. LUMA X and LUMA X-UV do have two ways to interface them while they are in operation: 1.) a REST-based API through which you can configure the modem and obtain modem and channel information 2.) a web interface running on a web server inside them modem through which you can configure the modem and obtain modem and channel information The API and web interface are documented in the LUMA X/X-UV manual which can be obtained on our web site. This documentation also contains Python examples for API access.
  • Do the LUMA optical nodes need a line-of-sight connection?
    Not necessarily. While the maximum range indicated in the data sheet requires a direct line of sight, indirect light from reflective surfaces or scattered light from particles in the water will often allow for a communication link even without line-of-sight.
  • What is the purpose of the LUMA power/data cable?
    All LUMA modems come with a Subconn connector which is suitable for underwater operations. However in order to test the modems on the bench or prepare them for deployment we developed adapter boxes for all of our modems which convert the Subconn connector to 1.) a standard barrel plug-style power connector and 2.) a micro-USB connector (with built-in USB to serial conversion) for our LUMA 100/250/500 modems or an RJ45 connector for our LUMA X and LUMA X-UV. We strongly recommend everyone buying their first LUMA modems to get these power/data cables along with the modems.
  • Do I HAVE to buy a power/data cable and a power supply along with my LUMA modem?
    You do not HAVE to buy the power plugs and power/data adapters from Hydromea, but we STRONGLY suggest it. Customer problems while setting up LUMA modems can often be traced back to connectivity issues, so the cables we sell provide a base-line test and development functionality which is very useful when setting up and integrating LUMA modems into your system. They also provide a reliable connection to a PC for firmware updates. We thus recommend every first-time buyer to get a pair of power/data cables along with the power supplies.
  • How can the full performance of the LUMA modems be demonstrated?
    To fully demonstrate the modem's capabilities, it's best to conduct tests in clear water at depths greater than 30 meters, during the evening or night, or indoors with lights off to minimize sunlight exposure. Turbidity in the water can also affect the expected range, with LUMA modems using blue light typically achieving about three times the visibility range in dark conditions compared to twice the range for LUMA X UV. In the environments with some ambient light present, LUMA X UV would work best as it operates in the invisible UV spectrum and is typically not disturbed by the visible light sources such as halogen and LED lights.
  • How do the LUMA modems adapt different environmental conditions such as range between modems, turbidity and ambient light?
    With the release of firmware V1.4, LUMA X as well as LUMA X-UV modems automatically adapt the emitter power (number of transmitting LEDs), the receiver sensitivity and the transmission speed depending to the signal-to-noise ratio (SNR) encountered. This feature can be disabled, allowing for a manual setting of transmitter power, receiver gain and transmission speed. For other LUMA models this feature can be implemented, contact us for further information.

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