Installing the DL1 in the vehicle
Mounting the DL1 in the vehicle
The DL1 should be mounted in the vehicle on a flat horizontal surface. For temporary installation you can just use the Dual-LockTM tape supplied, or for a more permanent installation the aluminium mounting brackets. The DL1 must be mounted with the buttons and lights facing either directly towards the back or the front of the car. Avoid any extremes of temperature and vibration for both the DL1 module and the GPS antenna. In particular, if the DL1 is exposed to vibration then the GPS data will become inaccurate.
Correct Mounting of the GPS Antenna
"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.
For correct, accurate operation of the GPS receiver it is absolutely essential that the antenna is mounted correctly. There are several important aspects to consider when mounting the antenna:
- The antenna must have a clear view of the sky in all directions. Note that it is NOT enough that the antenna can see vertically upwards towards the sky, it must also be able to see all the horizons as well. The GPS system actually gets very little positional or speed information from the satellites directly above, it gets far more information from satellites on or near the horizon. For example if the antenna was mounted in the bottom of a "bucket", so it could upwards but no horizons, then the GPS system would lock and provide positional information - but the accuracy would be very poor. In practice this all means that the antenna should be mounted on the highest point of the vehicle.
- The antenna must be mounted on a horizontal surface. The antenna must be mounted on a horizontal orientation facing directly up. The underside of the antenna cannot receive GPS information, similarly don't mount the antenna on a vertical surface.
- The antenna must not be covered in tape, in particular dark coloured tapes. Many tapes absorb the weak GPS radio signal. In general, black tapes are the worst in this respect as they contain high amounts of carbon - however, to be safe, avoid using any tape at all.
- The antenna must not be subjected to high levels of vibration. Although the antenna is physically robust to vibration, it can and does affect GPS reception, so isolate it as much as possible.
- The antenna must be physically remote from sources of electrical noise. The GPS radio signal is very weak and can easily be blocked out by radio interference, so to get a good signal the antenna must be as far away from radio interference as possible. By far the strongest source of radio interference is a gasoline engine's ignition system, so keep the antenna away from all aspects of it including the engine management system, coil, leads, distributor etc.
- Avoid trapping, pinching or kinking the antenna cable. The lead from the GPS antenna to the receiver is a special very high frequency cable and it is not normally practical to repair it - so if you do trap, pinch or cut it then the antenna will have to be replaced and this isn't covered by the warranty. Do not try to feed the antenna cable through a closure gap that is too small or compress it with a door seal or window seal.
- If at all possible, mount the antenna on a metal platform. The GPS radio signal is amplified if the antenna is mounted on a metal plate (termed a ground plane), and the bigger this plate is the better it will be for GPS reception. This is not essential for correct operation, but it is desirable.
- Allow time for the GPS system to lock on before sampling data. The GPS receiver typically takes one to two minutes to lock on to all the available satellites. The time to lock onto satellites varies significantly with conditions but is minimised when the vehicle is stationary.
Recommended mounting positions for the GPS antenna
- If the vehicle has a roof, this is the ideal place to mount the antenna.
- Alternatively, the best mounting position on a car may be the roll over bar or the top of the windscreen frame.
- On a motorbike, mounting is a little more difficult, but the best compromise is on a flat area of the tail unit, behind the rider.
- Poor mounting positions on a car include behind the front or rear windscreens.
Note: If you fail to adhere to the guidelines above, the GPS will still probably perform "adequately" "most" of the time, however when conditions are more challenging (with tree cover or bad weather etc) the positional accuracy will be significantly reduced.
Connecting the GPS module (if used)
Place the GPS antenna on the roof of the car, and screw the antenna connector onto the gold connector on the back of the DL1.
Connecting the power cable
If there is a cigarette lighter socket available on the vehicle, then the power lead provided can be used as a simple convenient way to supply power to the DL1. If not, connect the DL1 to a fused power source, which is available when the ignition is turned on. Connecting to a permanent power source will cause the DL1 to drain the battery continuously. Please do not connect anything to your car unless you are confident in what you are doing!