Vaisala GA31, User Manual

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Chapter 2 ________________________________________________________ Product Overview
CHAPTER 2
PRODUCT OVERVIEW
This chapter provides a general description of the Vaisala GPS
Antenna GA31.
General
The Vaisala GPS Antenna GA31 is intended for reception of C/A
code signals from the NAVSTAR satellites. These signals are Right
Hand Circular Polarization (RHCP) centered at 1575.42 MHz. The
GA31 is suitable for stations equipped with the GPS wind finding
system.
The Radiator Element with the Low Noise Amplifier module is a
commercially available GPS antenna unit, that rejects the unwanted
Left Hand Circular Polarisation (LHCP) and out-of-band signals. The
antenna filters, amplifies and transfers the signals to the navigation
unit for further processing.
The GA31 differs from GA20, another GPS antenna version, in that it
includes an N-to-TNC cable for connecting the antenna to sounding
instruments.
Construction
The active GPS Antenna module consists of an L1 frequency antenna
element integrated with an internal interference rejection filter and
Low Noise Amplifier (LNA). The element is enclosed within a
radome with an attached mounting base. A single N connector carries
both the GPS signal to the navigation unit and the 5-voltage power to
the LNA. The radiator element and preamplifier are housed in a
watertight round-shaped plastic radome that is mounted on top of the
1.5-meter pole.
VAISALA ________________________________________________________________________ 7