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Tripmeter calibration

Calibration of the Classic Metrometer is an important process that allows precise distance measurements while driving. With calibration, the device is able to interpret the pulses from the speed sensors in the context of the actual distance.

There are two basic ways to calibrate a tripmeter:

Calibration by known distance:
In this case, a road section of known length is used to measure the distance. After driving this distance, using the buttons on the device, the distance value on the metrometer is set equal to the length of the calibration section. When the value on the tripmeter corresponds to the actual length of the section, the calibration is complete.
Pre-calibration by calculation:
This method of calibration involves calculating the calibration value based on the specifications of the vehicle and the sensor. For example, if the sensor generates two pulses per wheel rotation, and the circumference of the wheel is 1930 cm, the calibration value will be 1930cm/2 = 965 cm = 0.965 m. Such a value is then set on the tripmeter.

In the case of a tripmeter with a built-in GPS module, there is additionally the possibility of GPS calibration. This is especially useful when measurements are made without sensors, and the road in the roadbook deviates significantly from the reference measurements.

Remember that accurate calibration is crucial to the precise operation of the tripmeter and requires careful execution. If you have any doubts, it is a good idea to consult the user manual or contact the manufacturer.

Definition of the vehicle calibration factor

The vehicle’s calibration factor is a key element in the calibration process. In the Classic metrometer, the calibration factor reflects the number of meters covered by the vehicle per pulse read from the speed sensors.

If the calibration factor is 0.50000, it means that each pulse from the sensor will cause the metrometer to accrue 0.5 meters of distance.

This ratio varies from vehicle to vehicle and depends on a number of factors, such as the size of the wheels, the number of pulses per wheel revolution generated by the speed sensor, and any differences in sensor design and installation.

The procedure for calibrating a metrometer is to set this factor so that the metrometer reflects the length of the calibration distance traveled as accurately as possible.

Remember that regularly checking and adjusting the calibration factor is key to maintaining the accuracy of your metrometer’s measurements.

Preparing for calibration

Measuring distance with the Metrometer Classic is an intuitive process. Before performing calibration, check during a test drive that the metrometer is counting the distance. The values may be incorrect, but the fact that the metrometer is counting the distance will roughly confirm to you that the sensors are installed correctly.

Note: in the version with GPS, the metrometer has two calibrations. One from the sensors and the other from the GPS. The GPSd = ON/OFF switch decides which calibration you do.

Calibration of the tripmeter according to the known distance

Hint: This calibration method is recommended when the tripmeter has had some calibration before. When the tripmeter is new or you anticipate that the calibration value will be significantly different from the previous calibration, look at the Pre-calibration by. calculations. If you do not do this you will be adjusting the calibration value at the end of the episode for a very long time.

Drive to a stretch of road of a length you know. For example, it can be a piece of road that has white posts marking the next 100m.

Try to have plenty of time for the first calibration.

Stop the vehicle at the beginning of the calibration section.
Reset the indications of the INTERMEDIATE and TOTALpath.
start driving and then stop at the end of the calibration section. The length of the calibration section matters. The longer the section, the more precise the calibration.

use the buttons: CALIBRATION, FAST , and the +10m and -10m switch to set the distance value equal to your calibration distance (if your distance was 1500m, that’s how much should be set on the meter).

Press the CAL button. The RGB LED will turn purple. The calibration factor value will show for 1 second and disappear. ODO will be shown on the screen. Continue to hold the button.
Using +/- 10m, increase or decrease the calibration value by 0.00001 (you can’t see it) which automatically recalculates the ODO value (you see it).
when you hold +10 or -10 it will start auto-repeat, that is, the calibration value will increase or decrease on its own at a rate of 50m/s.
when together with the CAL button and +10m or -10m is pressed the FAST button, the calibration value increment will accelerate significantly.
When you match the indication of the road to the length of the calibration section release the CAL button.
The calibration is done.

Attention: Calibration from pulses takes a value from 0.00001 to 9.99999. It cannot be zero.

Pre-calibration by calculation

Knowing how the sensor is installed in your vehicle, you can pre-calculate the calibration. I will present this with an example.

Car: Mercedes Pagoda.
Sensor: inductive in the hub which counts two pulses per wheel rotation.
Preliminary calculations:
- Measure the circumference of the circle with a yardstick or count it from the radius or diameter.
- your sample result is : 1930cm
- perform the action: 1930cm / 2(pulses/turn) = 965cm = 0.965m
- The value of your calibration is 0.96500. Set such a value with the CALIBRATION, FAST buttons and the +10m and -10m switch, using them as in the Calibration by known distance method.
done. You just calibrated the tripmeter.

GPS calibration

If your tripmeter has a built-in GPS module, you can calibrate it. GPS calibration may be needed when you take measurements without sensors and the road in the roadbook deviates significantly from the reference measurements.