Sports Sensors gloveRADAR GR360 Owner's Manual page 7

These readings are generally infrequent and in no way demean the
integrity of these precision instruments for practical ball speed measure-
ment applications.
Some "Radar Speed Guns" measure the speed of the ball after it has
travelled 6-8 meters from the thrower. Anomalous readings due to the
pitcher's motion are less likely, and the signal processing of numerous
"Doppler cycles" can result in an accurate measurement less influenced
by false target "ghosts". However, the travel distance after ball release
results in a speed reading about 3 MPH less than that of the guns which
measure ball release speed. Thus, these devices are often referred to as
"slow guns", and their speed readings are closer to the average speed
of the ball travelling between the pitcher and the batter.
The Glove Radar works on the same Doppler principles as the
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conventional "Radar Speed Guns" but transmits much less power, due to its'
smaller single-cell battery power supply. It also has a much broader antenna
pattern to accommodate use with the variety of glove sizes and configura-
tions to which it is designed to be attached. Thus, the Glove Radar
illuminates the approaching ball with a much lower "microwave energy
density" than the larger, more expensive guns.
The speed of the approaching ball is measured by the Glove Radar
within a few meters of receipt of the ball into the glove to which it is
attached. This is the ball velocity as it essentially reaches the batter, after
slowing-down at approximately 1 MPH per 7 feet of travel. At the 60 feet 6
inches baseball pitching distance, the resulting velocity measurement will be
about 9 MPH lower than the "fast guns" and about 6 MPH lower than the
"slow guns". For a youth pitching distance of 46 feet, and slower ball
speeds, the difference between the "fast guns" and the Glove Radar
ings will be about 6-7 MPH. A softball pitched from 40-43 feet will be about
5-7 MPH lower at the catcher, depending upon the variables cited
above.
The accuracy of the Glove Radar
more expensive radar guns when positioned to measure ball speed in
the same location. Comparisons can be made by facing the nearby ball
receiver who is wearing the glove-attached Glove Radar
radar gun toward the receiving glove. The distance from the receiver of the
ball should be the minimum practical at which the radar gun will measure
the ball speed.
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compares closely with that of the
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and pointing the
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It is of interest to note that the ball speed measured by any radar is that of
the ball velocity vector directly toward the radar. If the radar is not
aligned with the actual flight path of the ball from the thrower to the receiv-
er, the radar speed reading will be reduced by the cosine of the angle by
which the radar is displaced from the ball travel path. This difference is
insignificant when the radar is located essentially in-line, or near alignment,
with the ball flight path. However, if any radar is positioned on the ground, or
on a tripod, such that it is appreciably away from the ball flight path, speed
measurement inaccuracies can occur.
Glove Radar
The broad antenna pattern and unique signal processing of the Glove Radar
facilitate speed measurements of virtually any ball which is caught in the
glove. However, if the glove is held such that the Glove Radar
downward, looking toward the ground without facing at least somewhat in the
direction of the ball, some balls can be "missed" by the radar. No radar gun
can see the ball when looking away from the balls' flight path. Since the Glove
Radar is measuring and calculating the speed as the ball is approaching the
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glove, the flight path vector created by any "break" on the ball is inherent in
the speed measurement. This feature is unique to the Glove Radar
that of radar guns reading the ball velocity at a greater distance from the
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catcher, before the break.
Doppler radar speed measurements indicate the relative closing, or depar-
ture, velocity between the object being illuminated by the radar and the
radar itself. If, in the act of catching the ball, the glove is moved vigorously
toward the ball, a slightly higher speed reading can occur. If the receiver
"gives" with the ball, moving the glove away as the ball is caught, then a
read-
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slightly lower velocity can be indicated. The normal movements in catching
most balls are not a serious factor in measurement accuracy, but lunging
for wild throws, and scooping-up low throws near or hitting the ground can
produce anomalous speed readings. As you use your Glove Radar
become acquainted with its' "personality", recognizing good readings and
ignoring anomalies. Don't be mislead by an unusually high reading as an
indication of sudden improvement, or a low reading as a loss of strength
or technique. Averaging several readings, and/or discarding the high and
low extremes is a good technique for assessing progress.
Variables
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