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Home / Sensors / Hi-Link 79G Water Level Detection Sensor LD7901B Millimeter Wave Radar Sensing Module Non-Contact

Attributes

Brand -
Category Robotics / STEM Teaching Tools / Sensors
Origin -
Operating Frequency 79 GHz
Detection Principle Millimeter Wave Radar (FMCW)
Sensing Type Non-Contact
Interface Protocol UART / TTL
Supply Voltage 5.0V DC ±5%
Operating Current < 60 mA
Detection Range 0 - 15 meters (adjustable)
Beam Angle Horizontal 10°, Vertical 10°
Operating Temperature -40°C to +85°C
Dimensions 25mm x 25mm x 3mm

6 reviews

A

Anonymous

Mar 31, 2026

Rating: 5/5

Reliable for harsh environments

Deployed three of these units in an outdoor agricultural setup. They have survived rain, dust, and temperature swings without issue. The non-contact nature means zero maintenance so far. Highly recommended for anyone building robust level sensing solutions.

A

Anonymous

Mar 23, 2026

Rating: 5/5

Solved our chemical tank monitoring issue

We needed a sensor that wouldn't react with mild acidic solutions. Since this radar module doesn't touch the liquid, it was the perfect solution. Installation was easy, and the readout is consistent. Will be ordering more for our other production lines.

A

Anonymous

Mar 20, 2026

Rating: 5/5

Compact and powerful

Impressed by the small form factor considering the performance. I am using this for a flood detection project near a riverbank. The ability to detect level changes without touching the water prevents biofouling. Documentation could be slightly more detailed, but the sample code helped get it running quickly.

A

Anonymous

Mar 18, 2026

Rating: 5/5

Excellent precision for industrial tanks

We integrated this LD7901B module into our prototype water storage monitoring system. The non-contact feature is a game changer as it eliminates corrosion issues common with probe sensors. Setup via UART was straightforward, and the data stability is impressive even with surface agitation.

A

Anonymous

Mar 17, 2026

Rating: 4/5

Good value for research projects

Purchased this for a university thesis on fluid dynamics monitoring. The accuracy is sufficient for our needs, and the price point is reasonable compared to industrial-grade alternatives. Just ensure your microcontroller can handle the UART baud rate correctly.

A

Anonymous

Mar 11, 2026

Rating: 4/5

Great module, needs careful calibration

The sensor works very well for detecting water levels in large containers. It took some time to tune the filtering parameters to ignore false positives from splashing, but once configured, it has been rock solid. The 79GHz frequency provides much better resolution than older 24GHz modules I've tested.

5 FAQ

Q: What is the maximum update rate for the distance data?

A: The standard output refresh rate is configurable via the UART command set, typically ranging from 10Hz to 50Hz depending on the selected detection range and filtering settings. Please refer to the AT command manual for specific configuration instructions.

Q: Can this sensor detect water through a plastic tank wall?

A: Yes, the 79GHz millimeter wave radar can penetrate non-metallic materials like plastic or glass. However, the wall thickness and material density may affect signal strength, so we recommend testing with your specific tank material to ensure optimal range.

Q: Does foam on the water surface affect the reading accuracy?

A: Heavy foam can attenuate the radar signal slightly, potentially causing minor fluctuations in the reading. However, the LD7901B includes digital filtering algorithms that help stabilize the output. For thick foam layers, you may need to adjust the sensitivity thresholds.

Q: Is there a library available for Arduino or ESP32?

A: We provide a basic C-language demo code and communication protocol documentation on our GitHub repository. While there is no official pre-compiled Arduino library yet, many users have successfully created their own drivers based on our provided examples.

Q: What is the power consumption in sleep mode?

A: The module supports a low-power sleep mode which reduces current consumption to approximately 10µA. It can be woken up via a specific UART command or a hardware trigger pin, making it suitable for battery-operated applications.

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