Sea Tel 9797A-27, Инструкция по установке и эксплуатации

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Setup 9797A-27 C-Band TXRX
5-2
Figure 5-1 Antenna stops In-line with Bow
5.4. Calibrating Relative Antenna Position (Home Flag Offset)
During initialization, azimuth drives the CW antenna until the Home Switch is contacted, which “presets” the
relative position counter to the value stored in the Home Flag Offset. This assures that the encoder input
increments/decrements from this initialization value so that the encoder does not have to be precision
aligned.
The Home Switch is a micro switch with a roller arm which is actuated by cam mounted on the azimuth driven
sprocket, or it is a hall sensor which is actuated by a magnet mounted on the azimuth driven sprocket, which
produces the “Home Flag” signal.
The Home Flag Offset is a value saved in NVRam (Non-Volatile RAM) in the PCU. This value is the relative
position of the antenna when the home switch is engaged. Presetting the counter to this value assures that
when the antenna is pointed in-line with the bow of the ship the counter will read 000.0
Relative (360.0 =
000.0).
In most cases when the antenna stops at the home
flag, it will be pointed in-line with the Bow of the
ship. In these cases Home Flag Offset (HFO)
should be set to zero. When “Optimizing
Targeting” small variations (up to +/- 5.0 degrees)
in Azimuth can be corrected using If it AZ TRIM as
described in the Optimizing Targeting procedure
above.
Large variations in Azimuth position indicate that
the Relative position is incorrect and should be
“calibrated” using the correct HFO value instead of
an Azimuth Trim offset. This is especially true if
sector blockage mapping is used.
If the antenna stops at the home flag, but it is NOT
pointed in-line with the Bow of the ship, it is
important to assure that the antennas
actual
position (relative to the bow of the ship) is the value
that gets “preset” into the Relative position counter.
By saving the antennas
actual Relative position
when at the home flag into HFO, you have calibrated the antenna to the ship.
5.4.1. To Calculate HFO:
If Targeting has been optimized by entering a large value of AZ TRIM; First, verify that you are able to
repeatably accurately target a desired satellite (/- 1.0 degrees). Then you can use the AZ TRIM
value to calculate the value of HFO you should use (so you can set AZ TRIM to zero). AZ Trim is entered
as the number of
tenths of degrees. You will have to convert the AZ TRIM value to the nearest whole
degree (round up or down as needed). Calculated HFO value is also rounded to the nearest whole
number.
If AZ TRIM was a plus value: HFO = (TRIM / 360) x 255 Example: AZ TRIM was 0200 (plus
20 degrees). HFO = (20/360) x 255 = (0.0556) x 255 = 14.16 round off to 14.
If AZ TRIM was a negative value: HFO = ((360-TRIM) / 360)) x 255 Example: AZ TRIM = -
0450 (minus 45 degrees). HFO = ((360 – 45) / 360)) x 255 = (315 / 360) x 255 = 0.875 x 255 =
223.125 round of to 223.
If Targeting has NOT been optimized, allow the antenna to initialize to its home flag position. Visually
compare the antennas pointing to the bow-line of the ship (parallel to the Bow). Note the antennas
position relative to the Bow. If it appears to be very close to being parallel to the bow, HFO will probably
not be needed and you can proceed with Optimizing Targeting. If it is NOT close, initialization was driving
the azimuth CW, note if the antenna appears to have stopped before it got to the Bow or if it went past the
Bow. You may be able to guess an approximate amount of how many degrees the antenna is from the
bow. This is only intended to help you initially find the satellite (which direction you will have to drive and