Novatel SUPERSTAR II OM-20000077 - Manual (Page 21)

Installation Chapter 3
SUPERSTAR II User Manual Rev 3 21
3.2.2 Power Connection
The input range for a SUPERSTAR II card is either 3.3 VDC or 5 VDC depending on your model. The input
range required for the FlexPak-SSII is +6 to +18 VDC.
3.3 Installation Considerations
The FlexPak receiver is waterproof. The SUPERSTAR II bare card must be mounted in a dry location. Locate
your receiver where it is convenient for cables to run to the power source, display device, and antenna. Form
drip loops in the cables to prevent moisture from running down the cables and into the receiver.
Mount the receiver several feet away from radio transmission equipment.
3.3.1 Antenna Location
Many GPS reception problems can be reduced, to some degree, by careful antenna site selection. Of primary
importance is to place the antenna so that unobstructed line-of-sight reception is possible from horizon to
horizon and at all bearings and elevation angles from the antenna. This is, of course, the ideal situation, which
may not be possible under actual operating conditions.
1. Try to place the antenna as far as possible from obvious reflective objects, especially reflective
objects that are above the antenna’s radiation pattern horizon. Close-in reflections cause strong
multipath signals. For a detailed discussion on multipath and site selection, see Section G.4,
Multipath starting on Page 71.
2. Care should also be taken to avoid coiling the antenna cable around the mounting base and
pinching the antenna cable in window or door jambs.
By default, the SUPERSTAR II uses satellites above 4.5 degrees elevation. The mask angle can be set to use a
different cut-off, as low as zero degrees (all in view), using Message ID# 81, Set Mask Angle (refer to the L1
GPS Firmware Reference Manual for more message details).
3.3.2 Base Station Location
Your receiver must be a BASE model to act as a base station. A list of models is in Appendix A of the L1
GPS Firmware Reference Manual and in our Price List available from the Sales side menu of our website
at
www.novatel.com .
1. The base station must be located on a site that is above all obscuring elements on the surrounding
terrain in order to have all satellites above the horizon visible at the base station’s antenna. The
intent is to have all satellites that are visible at the roving unit’s antenna to be visible at the base
station as well.
2. Multipath interference must be minimized as much as possible. Multipath is defined as the
interaction of the GPS satellite signal and its reflections. This causes errors mainly on the GPS
code, and less so on the GPS carrier. Even though the receiver uses carrier phase measurements, it
can revert to code differential GPS operation if carrier phase differential GPS cannot be
performed. Hence, the base station’s antenna must be far from any reflecting elements.
3. The position of the base station’s antenna must be surveyed using appropriate surveying
equipment. This position must then be programmed in the base station using Message ID# 80, Set
User’s Position/Operating Mode (refer to the L1 GPS Firmware Reference Manual). Any error in
the base station’s position will be reflected in the roving unit’s computed position.