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13. Frequently Asked Questions (FAQ)
Q . My surface velocity measurement reading is much higher than
the last time I took a reading .
A . If the water surface is smooth with very little or no roughness,
the SVR™ is possibly not receiving enough returning radar
energy from it . Try to make your measurement closer to the
water or in a region where some water surface turbulence,
roughness, or even floating material is on the water .
Q . I just completed making a measurement and moved to a
different spot on the river . Now my measurements seem off .
A . Check to make sure you have adjusted the horizontal (yaw) angle
compensation . In high flow conditions, an incorrect or improper
angle input can yield a significant difference in velocity readings .
Q . The water has some good roughness and waves on the surface,
but the radar gun still seems to give me a higher and/or much
lower reading than I expect .
A . Make sure you are not too far away from the water surface when
making a measurement . This distance is sometimes difficult
to determine, because the measurement is a function of the
amount of returning signal to the radar gun . The returning
signal directly relates to the distance from the water surface
and the water surface roughness . The radar gun makes the
best measurements, even for very low velocities, when it is as
close to the water surface as possible . You need to make several
measurements pointing at the same spot . Try to minimize the
horizontal (yaw) angle in the measurement . Also, make several
measurements at different vertical (pitch-down) angles to
determine a consistency in the readings . Make sure you hold the
gun steady and at only one angle when making a measurement .
Q . I am trying to make a velocity measurement that appears to
be lower than 2 fps ( .60 m/s), but my readings show a higher
velocity .
