Installing the SPEEDBOX20
The following checklist is designed to be a quick reference for connecting the system in day-to-day usage. It is recommended that the more detailed explanations of each step are read in their entirety before initially installing the unit.
• Ensure the power is OFF.
• Connect the supplied antenna to “GPS 1” on the unit. For the RTK option, connect the “base” antenna (which is nearer to the rear of the vehicle) to “GPS 1” on the unit and the “moving” antenna (nearer the front of the vehicle) to “GPS 2”.
• Connect the 12-way Binder connector on the loom to “CONN 1” on the unit.
• Mount the antenna(s) on the vehicle roof – do not crush the cable in the doors or windows.
• Secure the unit safely in the vehicle, taking careful note of the mounting orientation.
• Connect the power to a 12V DC supply, e.g. a “cigarette-lighter” type plug, or other fused power supply.
"WARNING": To avoid any possible damage to the car paintwork, please take care when mounting magnetic GPS antennas. In particular make sure that there are no dust or grit under the antenna. In some cases it maybe required to add additional protection to the paintwork prior to mounting the antenna to avoid damage.
Mounting the SPEEDBOX20 unit
In order to give accurate acceleration readings, the SPEEDBOX20 should be mounted so that it is flat and level. It should also be securely restrained so that it cannot move in relation to the vehicle. The orientation of the unit is, of course, important. When mounting the unit, please ensure that it is oriented in the following manner:
Figure 2: SpeedBox20 Top View
In the longitudinal direction, this will give positive readings for acceleration and negative readings for deceleration and braking. Lateral acceleration will give positive readings for cornering around a right hand bend and negative for cornering round a left hand bend. The high accuracy speed output from the combined accelerometer and GPS data is robust to a mounting angle of approximately 20° from level, but it is advisable to obtain a mounting position as close to flat and level as possible to guarantee best accuracy. Speed accuracy readings taken whilst travelling over bumps are particularly prone to errors caused by an incorrect mounting angle. Neither the raw 20Hz GPS position and speed outputs nor the angular measurements from the RTK option are sensitive to the mounting orientation.
Note: Ideally, the SPEEDBOX20 should be vertically below the GPS antenna to ensure that both the accelerometers and the GPS antenna “see” the same velocity. In practice this is a small effect that, for most tests, can be ignored.
The unit can be securely restrained in the required position, either by bolting it in place through the four 4mm diameter holes that are pre-drilled in the unit, or by using a secure locking tape. “Scotch-Lock” or other similar products would be suitable for this application.