Jamar RAC Plus I, User Manual

Page: 28 / 56

RAC Plus I User’s Manual
3-2
Automatic Calibration Procedure
In order to accurately measure distance, your RAC Plus must know the exact
distance that the vehicle will travel based on pulses from the vehicle's speed
sensor. The calibration number is the automatic calculation that represents
the number of pulses received over a set distance. This number, once cal-
culated, will remain accurate until a change to
the vehicle occurs, such as different size tires are
put on the vehicle, tire wear, tire pressure change,
etc. Such changes will require a re-calibration in
order to maintain proper accuracy.
The RAC Plus has the ability to store four (4) separate vehicle calibration
numbers in memory. This simplifies sharing one instrument between up to
four different vehicles.
In order to calculate the calibration number for your particular vehicle, you
must first establish a
calibration course
. The length of the course can be
any known distance more than 500 feet. One thousand feet is ideal, but the
course can be any distance over 500 feet (for example, 623 feet from pole
to tree). Your course should be
straight and accurate , so take the time to
measure the course using a 100' tape or hand wheel. Mark the beginning and
ending points so they can be seen from inside your vehicle. Remember, the
course length can be any
accurate
distance over 500 feet, so for convenience
you could use a telephone pole or other marker as reference point.
Note: If you are using the Metric unit of measuring, laying out the
calibration course in feet is required to obtain the most accurate cali-
bration number.
Step 1
Slide the ON/OFF switch to ON. Your
RAC will perform a brief Self Test.
The current calibration number will
be shown in the larger, upper display
(D-1) and CF U(vehicle 1, 2, 3 or 4) in
the smaller, lower display (D-2). This is
displayed for 3-4 seconds while a tone
sounds, then
0 is shown in D-1 (0.000 if the mile or meter unit of measure-
ments is selected) while
CH
is shown in D-2.
Your RAC Plus must
be calibrated in
order to accurately
measure distance.
Fig. 3.1
Calibration Display on Start-up