Safiery STAR-Tank Radar Sensor Positions and Calibrated Depth
STAR-Tank uses reflected radio waves at 60GHz. It is therefore important that the sensor is away from the edge of the tank and free from baffles. The test setup above is a nominal 40L tank with 25L of water in it. The Centre Test Sensor is reading correctly as the range for the bottom of the tank is set correctly at 35.6 cm in this example. 1 Test Sensor 5 was calibrated at same bottom reading then lifted up to the raised side section of the tank which is 9 mm higher. This meant the distance to the water inside was 9 mm longer. At 40L for 356mm depth, the volume per mm is approx 0.1124 L. So raising 9 mm will reduce the aparent volume by 9 x 0.1124 = 1.011 L. 2 Test Sensors 2 and 10 are too close to the edge. The Frenzel lens is set to give a 30 degree cone of trasmission. The side is interferring with this giving a 100% reading for Sensor 10 and 94% for Sensor 2 which is a little further from the edge.. 3 If the tank is a shallow tank of say 200-250mm depth, the standard STAR-Tank sensor will show fluctuations when full as the top dead band is a percentage of full scale setting. For a nominal 1m calibrated sensor: the top deadband is about 50mm. The sensor is 16mm above the bottom of the housing leaving 34mm below top of tank. Generally, full tank accuracy is not important. But if this irritates you, then set the tank level in the Cerbo to Full at a value greater than 0. Here is a guide.
20~50 cm Depth
50~100 cm Depth
100~ 200cm Depth Dead band 50-70mm When tank is full. But won’t read past 2,000mm
Dead band 9-15mm When tank is full. But won’t read past 500mm
Dead band 30-35mm When tank is full. But won’t read past 1,000mm
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