The GPS speed sensor is designed to deliver speed signal to the tripmeter. It does not require calibration. The indication does not dependent of the type of car, it’s tyre sizes or axle ratios.
The GPS speed sensor consist of the electronic box and an external GPS antenna. Newer versions have a SMA type GPS antenna connector.
This diagram below shows how to connect the device depending the old/new type of the device.
The antenna, thanks to the built in magnet can be easily attached to any metalic part of the car. The top of the car is usually giving best results.
The source of power must reliable and stable, providing a value between 8 to 30 V.
After connecting the power the GPS speed sensor starts - light 1 flashes slowly. After 1 second, the device start searching for GPS satellites - light 2 flashes fast. Once correct signal found light 2 turns into continuous light. The device will now generate pulses aevery time the vehicle speed is greater than 3km/h.
Tripmeter calibration value should be set to 4545 pulses per km.