Gnss Antenna Cables; Static Port; Odometer; Factory Vss Signal - Advanced Navigation Spatial FOG Dual Reference Manual

9.6

GNSS Antenna Cables

The antenna cables should be routed away from powerful RF emitters, high current
wiring, high temperatures and any rotating or reciprocating machinery. It is very
important not to bend the antenna cable beyond it's maximum bend radius. It is
recommended to use wide cable ties and be careful not to do them up too tight.
Advanced Navigation recommends using either RG58 low loss or LMR240 coaxial cable
combined with high quality connectors. LMR300 and LMR400 can also be used to
minimise loss for very long antenna cables.
Cable Type
RG-58/U Low Loss
LMR240
LMR300
LMR400
Table 17: GNSS antenna co-axial cable properties
9.7

Static Port

Spatial FOG Dual uses atmospheric pressure to stabilise its vertical velocity. The static
port vents can be found on the sides of the Spatial FOG Dual enclosure at the top.
These are special vents that do not allow water to enter the enclosure.
9.8

Odometer

On ground vehicles, the use of an odometer input can greatly improve Spatial FOG
Dual's navigation and orientation solution during GNSS dropouts. With a high
resolution wheel encoder Spatial FOG Dual can be used to navigate indoors with GNSS
disabled altogether.
There are several different options for odometer installation which are listed below.
9.8.1

Factory VSS Signal

Most road cars since 1980 contain a VSS (vehicle speed sensor) signal that can be
wired directly into one of Spatial FOG Dual's GPIO pins. The vehicle should be taken to
an automotive electrician to perform the work.
To setup the odometer, the appropriate GPIO pin should be set to the odometer input
function using Spatial FOG Manager, see section 11.8.6. The odometer pulse length
must then be set either manually or automatically, please see section 10.9 for more
information.
For more information on the GPIO signals and their requirements please see section
12.4.3.
9.8.2

OBDII Odometer Interface

For applications where it is undesirable to modify the vehicle or the system needs to
be used with multiple vehicles, the OBDII odometer interface may be a better solution.
Spatial FOG Dual Reference Manual
Minimum Bend Radius
20 mm
20 mm
22.2 mm
25.4 mm
Page 36 of 138
Version 1.0
26/06/2015
Signal Loss
~0.92 dB/m
~0.33 dB/m
~0.26 dB/m
~0.17 dB/m