Campbell Scientific DCP100 GOES Data Collection Platform - Manual (Page 15)

DCP100 DATA COLLECTION PLATFORM
7
(22,300 miles)
36 (Elevation Angle)
E
(90 )
S (180 )
W
(270 )
N
(360 )
213 (Azimuth Angle)
DATA
COLLECTION
PLATFORM
ANTENNA
GOES SATELLITE
EXAMPLE ORIENTATION
FIGURE 6.3-4. Example Antenna Orientation Diagram
7. FORWARD AND REFLECTED
POWER
Forward and reflected power are measured (in
decimal units) and updated during each
transmission (see Sections 8 and 9). The
forward power must be between 165 and 215
for the transmitter's output level to be within
specifications. The antenna/cable assembly is
operating properly when the percentage of
power reflected is less than 5. A reflected
power reading of 27 is 5% of 165 and 2.7% of
215.
This percentage can be estimated with the
following equation (see the datalogger program
in Appendix D.3).
% power reflected =
[((ref + 17.4)/(fwd + 17.4))
2
x 100] - 1
When the percentage of power reflected is
greater or equal to 5, one or more of the
following situations exist and must be corrected:
•
The antenna is not connected.
•
The antenna is too close to metal.
•
You are transmitting inside a building.
•
The antenna is covered with snow or ice.
•
The frequency that the antenna is tuned to
does not match the transmitter's frequency.
•
There is a problem with the coaxial cable
connector or connection.
•
There is a problem with the antenna cable.