Doppler Current Meter: Accurately Capturing Current Velocity and Direction

1. Introduction to Doppler Current Meter

The Doppler current meter is an online Doppler current meter that can measure the output vector average velocity and directional current. The instrument also records tilt, heading, ping count, single ping standard deviation, and signal capability.

2. Characteristics of ocean current meter

In order to reduce the influence of water flow on the measuring equipment itself, the actual measurement range should be less than 0.4 meters from the distance of the current meter itself.

The instrument may tilt due to the influence of ocean currents when used in water, especially when fixed with cables. Therefore, an angle sensor is built-in to measure the tilt angle and correct flow velocity errors.

Built in electronic compass to output the direction of flow velocity.

The changes in flow velocity in the ocean are often slow because there is no need for continuous measurement. At the same time, in order to save battery power and extend the service life of the transducer, sampling intervals can be set according to the needs of the site. After completing the measurement of a set of data, a certain period of time can be used for measurement, and the length of the interval can be determined according to the site conditions.

3. Principle

Doppler current meters typically have two orthogonal sensor axes, with two flow sensors installed on each axis, allowing for bidirectional measurements on each sensor axis.

There are flow sensors in all four directions, including southeast, northwest, and northwest. By enabling the forward measurement function, the interference of eddy currents around the sensor and anchor chain can be reduced.

During the measurement process, sensors on each axis alternately send acoustic pulses and receive acoustic pulse reflection signals from particles, thereby measuring the orthogonal velocity components of the X-axis and Y-axis. By using tilt compensation and the orientation calculation of the built-in solid-state electronic compass, the velocity components in the north and east directions can be obtained. After multiple measurements and averaging, output the flow velocity and direction.

The measurement of ocean current direction can be used to correct sensors, and accurate north and east directions can be obtained through built-in electronic compasses and tilt sensors. The components of solid-state sensors are very suitable for monitoring low velocity ocean currents. The sensors start measuring at a distance of 0.4 to 1.0 meters from the instrument, which reduces the impact of ocean fouling and local eddies.

4. Technical indicators

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 indication.

2) Flow measurement range: 0-360 °; Flow resolution 0.01 °; When the inclination angle is less than ± 7.5 °, the flow accuracy is ± 5 °.

3) Tilt angle measurement range: -90 °~+90 ° resolution 0.1 ° accuracy ± 1.5 °

4) Acoustic frequency: 1.9 to 2.05 MHz. Instantaneous transmission power of 30. Wabo beam angle is 2.5 °.

5) Installation requirements: The distance from the water surface should not be less than 0.75 meters, and the distance from the bottom of the water should not be 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, directional angle, north-south flow velocity, east-west flow velocity, X-axis inclination angle, Y-axis inclination angle.

9) The parameters that can be set for the serial port include seawater sound velocity, measurement PING number, distance from the starting point of the measurement area to the current meter, and distance from the ending point of the measurement area to the current meter.

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

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

12) Volume: diameter 120mm, height 300mm.