TRACKING TUTORIAL
D-4
11. Select Receive -3 dB beamwidth [deg] and enter the value obtained above.
12. Select Step size [deg]. This parameter should be set to approximately 8
percent of the -3 dB beamwidth, but no less than 0.02 on systems with
standard resolvers. Enter the value and press [ENTER].
13. Select Position deadband [deg]. This parameter should be set between 5% &
10% of the -3 dB beamwidth, but no less than 0.02 on systems with standard
resolvers. Enter the value and press [ENTER]. Answer yes to the system
prompt to save changes and press [PRIOR] to return to the Main menu.
In normal environments, no other steptrack defaults require modifications from the
preset values. The OPT defaults should remain at factory settings also.
SETTING THE OPTIMAL TRACK SPEED IN THE AZ & EL, AC INVERTERS
NOTE: This procedure is for estimating the Optimal Track Speed. After using this
procedure, you may still have to make speed adjustments to obtain the correct
track speed for your antenna and local conditions.
A. The 7150DU (See Section 4.4.1.2.2 AC Inverter Setup) has a parameter
called NO25. This parameter sets the Track speed of the AZ or EL Axis. This
speed is expressed in Hz. The Speed Range is 0 to 50 Hz. The factory
setpoint is 5 Hz.
We will use the following calculation to create an optimal track speed. It will be
10% of the 3 dB beamwidth. To calculate the (3 dB beamwidth)/10, use the
following equation:
freq = receive frequency (in GHz): C-Band = 3.95 GHz
X-Band = 7.50 GHz
Ku-Band = 11.95 GHz
size = antenna diameter in meters
OPTIMAL TRACK SPEED = ______19________________ / 10
(Deg per Sec) frequency (GHz) * size (M)
Example: Antenna size = 7.2 M
C-Band = 3.95 Ghz
(19 / (3.95*7.2)) / 10 = 0.066 Optimal Track Speed (Deg per Sec)
B. We will now determine the actual track speed of the antenna.
Set the 7150DU to Manual mode. Using the PMCU, set to Track Speed, record
the current AZ angle. Run the AZ motor for 60 Seconds. Record the ending
angle . Subtract the two angles and divide by 60. This will be your actual track
speed.
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