Watson Industries, Inc.
DMS-EGP02 Rev A 03/28/2008
4
velocity scale factors can be handled through simple changes in the scale factor stored in the
EEPROM in the microprocessor. This can be done with a PC and the assistance of the factory.
Installation
Orientation
The connector face of the unit must point in the forward direction. The “G” command is used to
align the DMS to True North. For more information on this command, see “Setting Heading
Calibration” section of this manual. The DMS drawing, with wire call outs, is located in Figure 2.
The DMS is a rugged device and will withstand harsh environments. However, due attention needs
to be paid to the nature of the sensor and its prime function, which is to measure attitude and
motion.
Mounting
Although a mounting plate is provided for a flat surface mount, the unit may also be adhesively
mounted at any of its surfaces. If high shock loads are expected (greater than 20G or repeated
shocks greater than 10G), appropriate shock mounting should be used to prevent damage.
Vibration isolation should be used if operation in 4G or greater vibration environments is expected.
The GPS antennas have magnetic mounts with two M2.6 mounting holes and need an unobstructed
view of the sky to receive signals from GPS satellites. The “Fore” antenna is placed ½ meter ahead
of the “Aft” Antenna on a line parallel to the axis of the vehicle.
Caution: The GPS heading accuracy is directly related to the accuracy of the antenna placement &
DMS alignment. Antenna placement must be within 1 cm of the 1/2 meter spacing for accuracy.
Environment
Avoid mounting sites that are subject to significant temperature changes over the duration of the
test. Temperature variation will induce noticeable rate sensor bias drift, which will result in
degraded attitude accuracy.
Power / Connectors
This unit has an internal regulator to allow operation over a wide voltage input range. Best
operation is obtained at either 12 or 24 VDC, although operation is fully satisfactory down to 10
VDC and up to 30 VDC. Power draw of the unit is about 8.1 Watts. Internal capacitors are
provided to remove a reasonable level of power line noise, however, capacitors should be added for
long power line wiring or if noise is induced from other loads on the circuit. The DMS power
system is isolated from the DMS signal system. The mating connector for the Power/Analog
Output Connector is a 25 Pin female D-Sub. Both GPS antenna connectors are on the side. For
more information on the connectors and pinout of the DMS-EGP02, see Figure 2.
Calibration
The DMS is calibrated at the factory before it is shipped to the user. It is recommended that the
unit be returned to the factory annually for evaluation and recalibration.
