PAVAS Set Calculation Mode

This menu is used to set the speed calculation mode.There are two methods that can be used to calculate the speed;

The first is to use a compassion technique as used by other speed measurement system. Here the vehicle is driven at a known speed and then a scaling factor is used to calibrate the PAVAS displayed speed. This method is independent of the rolling circumference of the tyre and the timing circuits in the MCU. This technique is easy to perform. It has a number of problems. The reference speed is usually taken from a GPS unit which only displays speed to 1 Kph and so accuracy is only +/- 1 Kph.To maintain a constant speed is difficult and the actual speed is suspect. This methods is called a Comparison technique. To achieve 1% accuracy a speed of 100 Kph is required.

The second technique is to measure the rolling circumference of the tyre and then use the MCU timing circuits to measure the difference between two wheel pulses and hence calculate the speed. PAVAS uses two methods and accuracies of 0.1% or better are possible.

In summary, the Comparison method is fast to calibrate but is limited in accuracy. The Wheel Distance (Wh Dist) method takes more effort but, is more accurate. Wheel distance measurements are mandatory for TSD and Regularity events.

To set the mode, move the cursor to the Compare or Wh Dist prompts. Press the Select button.