RESEARCH CONCEPTS RC2000C Manual page 42

34 RC2000C Az/El Tracking Antenna Controller
Here is the procedure:
1. Identify a location on the antenna to place the inclinometer. The location on the mount should be
selected so that one degree of movement about the elevation axis registers as one degree on the
inclinometer. It is best to use an inclinometer that has a magnetic base. These are available from
hardware stores.
2. Record the elevation position count and the reading of the inclinometer. These will be designated
CNT_1 and DEG_1, respectively.
3. Jog the antenna in elevation. It is recommended that the antenna be moved 15 to 20 degrees in
elevation. Record the elevation position count and the inclinometer reading. These will be
designated CNT_2 and DEG_2.
The elevation region over which the measurements are made should correspond to the range of
elevation angles which will be encountered in operation (i.e. the elevation values over which the
satellites will be found).
4. Use the following formula to calculate the Elev Constant:
( (CNT_2 - CNT_1) / (DEG_2 - DEG_1) ) * 57.29
(_______ / _______) * 57.29 = _______ (Count per Radian)
If the result is negative, change the sign to positive.
Here is an example:
Place the inclinometer on one of the back support struts of the antenna. The antenna is located near
Kansas City, Kansas, USA (latitude 39 N, longitude 94 W). A satellite located longitude 94 W has an
elevation look angle of 44 degrees relative to the horizon. The normal range of elevation movement is
20 to 45 degrees.
Positioning the antenna at an elevation angle of 21 degrees, the count is 435. Record CNT_1 as 435
and DEG_1 as 21 degrees. Move the antenna up in elevation to an angle of 43 degrees where the
count is 1272. Record CNT_2 as 1272 and DEG_2 as 43. Perform the calculation:
( (1272 - 435) / (43 - 21) ) * 57.29
simplify to obtain...
Round this up to 2180 and enter this value at the Elev Constant CONFIG mode prompt.
Elev Scale Factor from Manufacturer's Specifications
If the antenna manufacturer gives an elevation position pulses per degree specification for the antenna,
simply multiply the value by 2 to obtain 'elevation position counts per degree' (because the RC2000
counts both the rising and falling edges of the position pulses). Multiply this 'position counts per degree'
value by 57.29 to obtain 'position counts per radian'. Round to the nearest whole number value to
obtain the Elev Constant CONFIG mode item.
_______ * 2 * 57.29 = _______ (counts per radian)
Azimuth Scale Factor
Research Concepts, Inc. • 9501 Dice Lane • Lenexa, Kansas • 66215 • USA
(837 / 22) * 57.29 = 2179.62.
Chapter 4
CNT1 _______ DEG1 _______
CNT2 _______ DEG2 _______
Inclined Orbit Satellites
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