3.1.1
Antenna Operation
The internal GPS antenna receives 5 Vdc and approximately 30 mA
from the clock, and provides about 35 dB of gain in a RHCP (Right
Hand Circular Polarization) omnidirectional pattern over the antenna.
Therefore, it is essential that the Model 1095A/C, or external antenna,
be mounted with the top side pointed up for proper reception of GPS
signals. See Figure 3.1.
3.1.2
Mounting Locations
Since the Model 1095A/C is designed to operate outdoors, it needs to
be mounted so that the top of the clock is pointed straight up at the sky.
See Figures 1.1 and 1.2 for antenna location inside the clock. Figure 3.1
illustrates the Model 1095A/C mounted above a structure with a clear
view of the sky in all points of the compass.
Pole Mounting
While a pole may obscure satellites in the direction of the pole, normally
there are enough satellites in view to compensate for the few (if any)
that are blocked. Even those that are blocked will eventually move into
view, as others may move out of view. Under most circumstances,
a pole will not block enough satellites for the Model 1095A/C to lose
synchronization. Note that once the Model 1095A/C is locked with a
good geographical position, it should stay synchronized with only one
satellite in view.
Panel Mounting
Use the included mounting tabs to mount the clock to a flat surface or
inside a panel. See the information on the included mounting tabs in
Section 2.6.
GPS Satellite Orbits, Positions and Reception
GPS satellites orbit the earth with a speed of 3.9 km per second and
have a circulation time of 12 hours sidereal time, corresponding to 11
hours 58 minutes earth time. This means that the same satellite reaches
a certain position about 4 minutes earlier each day. There are six orbital
planes at an inclination of about 55 degrees above the equator, and
rotated by 60 degrees around the equatorial plane. With four satellites
in each orbital plane, there are a total of 24 active satellites with several
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