Figure 1, Picture of the EasyQ, with two transducers to measure the water velocities and one transducer pointing vertically upwards to measure the water level (stage)

Two different tests were made with the EasyQ. One to check the the water level measurement, and one to test the velocity measurements.

To check the level measurements, the actual distance was continuously monitored using a steel measuring-tape. The results are shown on figure 2.

Figure 2, Water levels measured by the EasyQ plotted against actual distance.

During the test the tilt of the EasyQ was smaller than 1º. These results match perfectly.

After that the effects were measured of a larger tilt angle. To measure this the EasyQ was placed in three different depths :0,30m, 1,21m en 2,43m. Measurements were made on each depth using different tilt angles, ranging from 0ºto 14º. Figure 3 shows that the error increases quickly at larger levels and small tilts

Figure 3, percentage good measurements at increasing tilt angle at different depths

Velocity measurements
To check the velocity measurements the EasyQ was mounted on a moving cart over a test tank. The cart may be moved at a controllable speed. The speed of water in the test tank was zero.

Cart on test tank.	Figure 5, results of the velocity measurements.Measurements marked "Snel" were taken directly after each other, without letting the water come to rest.

The measurements were taken at 15 to 30 minutes interval to give the water in the tank time to come to rest. Only the measurements marked "snel" were taken without any interval. Results are shown in figure 5 geeft een overzicht

Author: Lee Gordon (NortekUSA)