Hughes Network Systems 24HX-001 Manual De Usuario

To install and align the ODU, you must know the assigned HT
alignment direction and know where this direction is relative to the
HT location. Plot the planned sectors on a local map as explained
in this section—then you will know the alignment direction for
each HT to be installed.

1.

Obtain the HT alignment direction for each HT to be
installed (for example, 45

°

, 135

°

, and so on) from the Site

Data Record (prepared by the site survey team).

2.

Find true north on the map.

3.

Find the hub site on the map, and clearly mark its location.

4.

Carefully plot lines for true north (0

°

), south, east, and west,

with the hub site at the intersection, as shown in figure 4-3
(page 4–7).

5.

Plot the assigned alignment direction for each sector, and
identify the sectors, using figure 4-3 as an example.

Figure 4-3 shows four sectors for 90

°

 ODUs. Sectors for

45

°

 or 22.5

°

 ODUs are 45

°

 and 22.5

°

 wide, respectively.  In

some cases, a full 360

°

 coverage range is not required.

6.

On the roof, determine where true north is.

You may be able to determine true north using only the map
and landmarks.

If you use a compass to determine magnetic north, you
must adjust for magnetic declination (deviation from
true north) to determine true north. Some maps show
magnetic declination; some show magnetic north versus
true north.

If you are west of the north–to–south line where declination
is 0

°

, the declination is east (or positive). If you are east of

the 0

°

 declination line, the declination is west (or negative).

To correct a magnetic compass reading to true north,
subtract east (positive) declination values from the
magnetic north reading. Add west (negative) declination
values. For example:

S If the declination is east, 14

°

, subtract 14

°

 from the

magnetic reading.

S If the declination is west, –14

°

, add 14

°

 to the

magnetic reading.