Decatur Electronics Surface Velocity Radar SVR2-01, Руководство пользователя

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When you point the SVR™ about 10 feet (3 meters) from the water
surface, it measures an elliptical beam pattern of 2 feet (61 cm) in
diameter . Keep this in mind when making measurements of a stream
width . Take several readings to completely cover the full width of the
stream .
9.2 Interference Sources and Remedies
When properly installed and operated, Doppler radar technology
is extremely accurate and reliable . However, variations in the
environment can cause situations and circumstances, which can
cause spurious (erratic and unusually low or high) velocities to
display . Signs that a velocity is spurious can include the following
characteristics:
• a reading appears when no target is in the operational range of
the antenna
• a target entering the operational range overrides the
interference signal, causing the display velocity to change
suddenly
• interference is irregular and does not provide a valid target
history
9.2.1 Angular Interference (Cosine Effect)
The cosine effect causes the radar device to display a velocity
which is lower than the actual water surface velocity . This condition
exists whenever the target's path (the water flow direction) is not
parallel with the radar gun’s antenna . As the horizontal (yaw) angle
between the antenna and the target's directions of travel increases,
the displayed velocity decreases . Ideally, an angle of zero (0°) is
best .