Applanix POS MV V5 Installation And Operation Manual page 31

Inertial Measurement Unit
The IMU comprises three solid-state linear accelerometers and three solid-state gyros arranged in a
triaxial orthogonal array. These sensitive components, together with the electronics to convert their
analog outputs into the digital information required by the PCS, are all contained in a sealed unit that
requires no maintenance.
Do not open the IMU housing for any reason. Opening the IMU
housing will void the warranty.
While the array of linear accelerometers sense acceleration in all three directions, the array of gyros
sense angular motion around all three axis centred on the IMU. The PCS receives these measurements
from the IMU and uses them to compute the measurements of motion. Refer to the Theory of Operation
description starting on page B-1 for a more detailed explanation of the POS MV operating theory.
GNSS Receiver
POS MV includes a dual antenna GNSS receiver card:
• A primary receiver provides the position, velocity and raw observation information to the POS MV.
It also provides a one Pulse Per Second (PPS) strobe together with a time message that the POS
MV uses to accurately time-stamp data output with Universal Time Coordinated (UTC) or GPS
Time.
• A secondary receiver, in conjunction with the primary receiver, allows the POS MV to compute
GNSS heading aiding by performing carrier phase differential measurements between the two
GNSS receivers.
The system includes two identical antennas with 15 metre (~50 feet) long cables. You must connect each
receiver to a GNSS antenna to receive GNSS signals from the orbiting constellation of satellites.
The antennas supplied with the system have excellent phase centre stability. If you use alternative
antennas with the POS MV, Applanix cannot guarantee the heading or position performance of the
system.
GNSS Azimuth Measurement Subsystem
GNSS Azimuth Measurement Subsystem (GAMS) is a unique feature of POS MV that allows the system
to achieve exceptional accuracy in the measurement of heading. The GAMS subsystem uses two GNSS
receivers and antennas to determine a GNSS-based heading that is accurate to ±0.02° (±0.03° for
WaveMaster) or better (using a two-metre [~6 ½ feet] antenna baseline) when blended with the inertial
Copyright © Applanix Corporation, 2017
POS MV V5 Installation and Operation Guide
I
MPORTANT
Introduction
1-5