Ultrasonic Anemometer 1D

Construction and mode of operation

The Ultrasonic Anemometer 1D consists of 2 ultrasonic transformers facing each other at a distance of 200 mm. The transformers operate both as sonic transmitters and as sonic receivers. On starting a measurement a sequence of 2 individual measurements runs in 2 directions of the measurement section with highest possible velocity. The measuring directions (directions of sound propagation) are alternated. Two individual measurements are averaged and used for further calculation. The time required for a measurement sequence is approximately 10 msec at + 20°C.

Measuring principle

The velocity of the sound propagation in calm air is superposed by an airflow. The velocity of the airflow is calculated from the difference of the propagation time of the sound with and against the airflow. As the velocity of the sound greatly depends on the temperature of the air, the propagation time of the sound is measured in both directions. This eliminates the influence of the temperature on the measurement result

Features

• The measured values are available as analogue signals and/or data telegram via a serial interface.
• Analogue output: Flow velocity with or without direction identification.
• Digital output: Flow velocity with direction identification and virtual temperature.
• The sensor arms are automatically heated in case of critical ambient temperatures, so that the function is guaranteed even in winter conditions.