Spektrum SPM1305 - Manual (Page 10)

10 SPEKTRUM TELEMETRY
• Set the car next to a ruler and at 0" then roll the car
forward by hand, counting each revolution of the reference
mark. At exactly 10 revolutions stop the car.
• Measure the exact distance that the car traveled in ten revolutions
and divide this distance by 10 (i.e. 12.0" divided by 10 = 1.20").
• In the Roll Out screen press the + or – button until 1.20 appears on the
screen. Now all the rpm related functions will be displayed in mph.
Method B
For this method you either need to know the internal gear ratio (normally
provided in the vehicle’s manual) or be able to calculate the ratio via
the number of teeth on the gears. It is also necessary to calculate the
circumference (distance around) the tire. Once the internal ratio is known,
and the circumference in inches has been determined, simply divide the
circumference by the internal ratio and use this value as the conversion.
To calculate circumference—multiply 3.14 x the tire’s diameter in inches
To calculate internal gear ratio—divide the larger gear by the
small gear. With multiple gear transmissions, it is necessary
to multiply each of the ratios to arrive at the final ratio.
Temperature Units
Signal Lap # Lap Time
Speed/RPM Voltage Temperature
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The Temperature Units screen allows you to select between Fahrenheit
or Celsius. To access the Temperature Units screen press the  or

button until Temp Units appears on the screen. Pressing the
+ or – button will change the units from Celsius to Fahrenheit.