In-Vehicle Installation Guidelines for FOX3-2G/3G/4G and BOLERO40 Series
9
INSTALLATION INSTRUCTIONS
1.4
Connection precautions
Selecting an installation location for an external antenna or device is critical:
If your product comes with an external glass-mounted antenna, then install the GNSS antenna in the vehicle
in the locations that are dry and distanced from sources of extreme heat and where the system can receive
GNSS satellite signals from all directions. During installing the antenna, be sure that the cable is extended
and not rolled up. When rolling up the antenna cables, the induced voltage caused by magnetic field may
effect on GSM and GNSS performances and operating voltage as well.
If you use a ground-mounted antenna, please ensure that the antenna ground does
NOT
come into contact
with vehicle body. This is recommended to avoid the ground loops, which may occur when there is more
than one ground connection path available.
If your product comes with built-in antenna (e.g. BOLERO40) or you want to use the device with internal
antennas (e.g. FOX3), then install the device in a suitable location that does not interfere with the GNSS/GSM
reception. Do not mount the antenna or devices with internal antennas on the metal plates as these may
disturb and attenuate the GSM signal.
When a location is found, then perform the test given in chapter
3.4.
Identifying suitable power sources for the unit is also critical.
Turn car ignition off before making any connection to the AVL device. Check the polarity of the battery
terminals with a voltmeter before connecting any of the Lantronix products in the vehicle. Later on, you have
to identify an electrical ground in the vehicle and it should be used as a common ground point for all ground
wires. Connect the unit ground wire to the identified ground ([-]) negative ground battery terminal or vehicle
chassis, see possibilities for power source connections below) and, only when all other connections are
made, connect the unit power lead (+IN) directly to the vehicle battery (+) positive terminal (12V/24V) by
using a 2A fuse.
Possibilities for power source connections:
A) Power is taken directly from the vehicle battery and the vehicle chassis is used as a common ground:
The vehicle chassis (
➋
) can be used as a common ground
ONLY WHEN
your vehicle does not have a main
switch (
➊
)
equipped between the battery negative terminal and the vehicle ground. If this switch is in your
vehicle and you select the vehicle chassis as a common ground, then the external power to the unit will
depend on the position of this switch. For non-battery-powered units, the unit is powered OFF, once this
switch is OFF.
B) Power supply pins are connected directly to the vehicle battery:
The battery negative (-) terminal can be used as a common ground
ONLY WHEN
no second ground occurs.
When an electronic accessory in-vehicle (e.g. radio, cool box and so on) uses the body of the vehicle for
ground, and the device ground pin is directly connected to the battery negative (-) terminal, this can form a
common return path if the antenna (
➌
) or device case comes into contact with vehicle body (Figure below
illustrates such ground-loops). In such cases, some vehicle accessories can limit the amount of ground that
other accessories can receive. This is commonly known as a ground loop. In other words, a ground loop is an
unwanted electric current path in a circuit resulting in interference, when two grounded points in the same
circuit have different potentials. To prevent such ground loops, it is recommended to shield your device and
the antenna so that no second ground occurs. Additionally, the device positive lead (+IN pin) must be
protected by using a 2A fuse. Most vehicle manufacturers recommend that when both leads (positive and
