I’ve just come across a no-name non-contact, high-precision 80 GHz mmWave radar sensor for liquid level detection with a 40m range, ±5mm accuracy, and Modbus communication over UART.
We had seen 24 GHz and 60 GHz mmWave sensors mostly for precise motion detection, but it’s the first time I’ve seen an 80 GHz mmWave sensor, or more exactly, 79 GHz. It operates on the same principle of Frequency Modulated Continuous Wave (FMCW) radar as most other mmWave sensors and connects to an Arduino or other board over UART. It targets applications such as smart water management, industrial process control, and environmental disaster prevention/monitoring.
Specifications:
- MCU – GigaDevice GD32F405 Arm Cortex-M4F microcontroller @ 168 MHz with 192KB SRAM, 3MB flash, 1MB code-flash
- Transmit frequency – 77–81 GHz (79 GHz mid frequency), 4 GHz bandwidth
- Output power (EIRP) – 13 to 20dBm
- Beamwidth (-3dB)
- Horizontal ±25°, Vertical ±25°
- With external lens: Horizontal ±3°, Vertical ±3°
- Modulation mode – FMCW
- Ranging range – 0.15–40m
- Accuracy – ±5mm
- Resolution – 1mm
- Startup time – 100ms
- Host interface – UART (Modbus protocol)
- Operating voltage – 3.5–5V
- Operating current – 30mA
- Dimensions – 35 x 35 x 1.2mm
- Weight – Module: 5 grams; with lens: 46 grams
- Temperature Range – -45°C to +85°C
The 0.15m to 40m range makes it suitable for monitoring large bodies of water like reservoirs and rivers, as well as deep industrial tanks. We’re told the narrow beam lens makes the radar module emit a highly focused radar beam with a narrow ±3° angle to enhance signal directivity and reduce interference from tank walls, agitators, or other surrounding structures.
All you need to do is connect the sensor to an Arduino board over UART (Tx, Rx, 5V, GND), and run an Arduino sketch relying on the LiquidLevelDetection library. Instructions and links to the library can be found in the wiki.
The 80 GHz mmWave liquid level detection sensor is sold on DFRobot for $59. I tried to find this sensor on AliExpress, but all I could find were more advanced 80 GHz mmWave meters with inlets going for $200+. On the other side of the price scale, there are also some cheap water level switches used at a fixed position that sell for a couple of dollars. [Update: another 79 GHz water level sensor is the HLK-LD8001 with a 15-meter range and selling for $45 on AliExpress for a kit without enclosure. Thanks to Scott for the tip in comments.]
Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.
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