User's Manual

Introduction
GMS-2 Operator’s Manual
6
The hand-held controller component of the GMS-2Pro
includes the Windows® CE operating system and color LCD touch
screen. Integrated Bluetooth® wireless technology allows this system
to be a cable-free controller/receiver for maximum portability. The
rugged casing is durable and built for rugged use.
As a field controller, the GMS-2Pro can run a full suite of field
software for working with total stations and RTK GPS systems.
The GPS+ receiver component of the GMS-2
can receive and process GPS+GLONASS L1 signals improving the
accuracy of your survey points and positions. The GPS+ features of
the receiver combine to provide a positioning system accurate for any
survey. Several other features, including multipath mitigation, provide
under-canopy and low signal strength reception.
When power is turned on and the receiver self-test completes, the
receiver’s 50 channels initialize and begin tracking visible satellites.
Each of the receiver’s channels can be used to track any one of the
GPS or GLONASS signals. The number of channels available allows
the receiver to track all visible GPS satellites at any time and location.
An internal GPS antenna equipped with a low noise amplifier (LNA)
and the receiver’s radio frequency (RF) device are connected with a
coaxial cable. The wide-band signal received is down-converted,
filtered, digitized, and assigned to different channels. The receiver
processor controls the process of signal tracking.
Once the signal is locked in the channel, it is demodulated and
necessary signal parameters (carrier and code phases) are measured.
Also, broadcast navigation data are retrieved from the navigation
frame.
After the receiver locks on to four or more satellites, it is possible to
solve the so-called “absolute positioning problem” and compute the
receiver’s coordinates (in WGS-84) and the time offset between the