Raven Viper Pro Installation & Operation Manual page 239

Enter the corrected speed cal of 631 [155].
7.
Confirm that the new Speed Cal is correct by repeating the procedure in the Verification of the Speed Cal
8.
Value section on page 227.
Wheel Drive Speed Sensor
Mark the tire on which the speed sensor is installed using chalk or a piece of tape as shown below.
1.
Mark the corresponding spot on the ground.
2.
Count 10 full revolutions of the wheel while traveling in a straight path. The mark must stop with the chalk or
3.
tape in the same orientation that it began at the starting point.
Calculating the Speed Cal with a Wheel Magnet Speed Sensor System
FIGURE 1.
Mark the stopping point and measure the distance between the starting and stopping marks on the ground
4.
in inches [dm]. Round to the nearest whole number.
Note:
This measurement is critical to the performance of the Viper Pro. Measure Carefully. Be sure tire
is properly inflated before measuring. If possible, measurements should be made in the type of soil
in which the vehicle will be operating. Tire circumference will vary when measured in soft or hard
packed soil. For best results, measure several times and average the results.
Enter this measurement as the new speed cal.
5.
Adjusting for Additional Magnets
Typically, four magnets are used with the wheel drive speed sensor. However, to ensure accurate speed
readings for large tires and very low speed applications, additional wheel magnets may be necessary. Any
even number of magnets may be used as long as they are of alternating color and equally spaced. After
calculating the speed cal, this number must be adjusted according to the number of magnets installed using
the following formula:
where ADJ = Adjusted Speed Cal, NM = Number of Magnets used and D = the Distance Measured.
Manual No. 016-0171-122 Rev. I
4
×
-------- -
D = ADJ
NM
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