Doppler current meter

1、Doppler current meter Product Introduction

Doppler current meter is an online Doppler current meter that measures output vector average velocity and directional ocean currents. The instrument also has the ability to record tilt, heading, ping count, single ping standard deviation, and signal strength.

2、Doppler current meter Product Features

To minimize the impact of water flow on the measuring device, the actual measuring range must extend at least >0.4 meters from the current meter itself.

Doppler current meter when used in water, especially when secured by a cable, the current may cause it to tilt. Therefore, an angle sensor is built-in to measure the tilt angle and correct for flow velocity errors.

A built-in electronic compass outputs the direction of the flow velocity.

Ocean currents typically change slowly, so continuous measurement is unnecessary. To conserve battery power and extend transducer lifespan, sampling intervals can be set according to site requirements. After completing a set of measurements, a time interval is allowed before resuming the measurement. The interval can be determined based on site conditions.

3、Doppler current meter Measurement Principle

Doppler current meter system typically has two orthogonal sensor axes, each equipped with two current sensors, enabling bidirectional measurements on each axis.

This provides current sensors in all four directions (north, south, east, and west). Enabling forward measurement reduces interference from eddies around the sensors and anchor chains.

During measurement, the sensors on each axis alternately send acoustic pulses and receive reflected acoustic pulse signals from particles, measuring the orthogonal velocity components of the X and Y axes. North and east velocity components are obtained through tilt compensation and orientation calculations using a built-in solid-state electronic compass. Averaging multiple measurements outputs the current velocity and direction.

The current direction measurement can be used to correct the sensors, achieving accurate north and east directions through the built-in electronic compass and tilt sensors. The solid-state sensor components are well-suited for monitoring low-velocity currents. Measurements begin at a distance of 0.4 to 1.0 meter from the instrument, minimizing the influence of marine fouling and localized eddies.

4、Doppler current meter Technical Specifications

1. Flow velocity measurement range: 0-500 cm/s; Flow velocity resolution: ±0.1 cm/s; Flow velocity accuracy: ±0.5 cm/s ±1% of indicated value.

2. Flow direction measurement range: 0–360°; Flow direction resolution: 0.01°; Flow direction accuracy: ±5° when the tilt angle is less than ±7.5°.

3. Tilt angle measurement range: -90°~+90°; Resolution: 0.1°; Accuracy: ±1.5°.

4. Acoustic frequency: 1.9 to 2.05 MHz; Instantaneous transmit power: 30 watts; Beam angle: 2.5°.

5. Installation requirements: Distance from water surface: not less than 0.75 meters; Distance from water bottom: not less than 0.7 meters.

6. Operating voltage: 9V–15V DC power supply.

7. Communication method: Serial communication (RS485 or RS232 optional). Communication protocol: Modbus protocol. 8. Output parameters: Flow velocity, flow direction, azimuth angle, north-south flow velocity, east-west flow velocity, X-axis tilt angle, Y-axis tilt angle.

9. Serial port configurable parameters: Seawater sound velocity, measurement PING count, distance from the start point of the measurement area to the current meter, distance from the end point of the measurement area to the current meter.

10. Operating temperature range: -5 to +50°C.

11. Weight in air: 1850g ± 100g (excluding bracket).

12. Dimensions: Diameter 120mm, Height 300mm.