COBHAM SEA TEL 9711IMA-70, Installation Manual

Page: 75 / 178

9711IMA-70 Setup – Satellite Configuration
11-1
11. Setup – Satellite Configuration
The values that these parameters are set to depends on the hardware configuration required for each satellite. Configure
each of the satellites that airtime services will be provided on so that any one of them can be selected, remotely or by the
user onboard. The satellite selection will in turn control the hardware on the antenna pedestal to select the correct TX & RX
hardware and the correct tracking settings.
Sea Tel provides quad-band LNBs as standard on the Ku-Band feed assemblies.
11.1. Searching Patterns
The MXP will initiate an automated search pattern after AGC falls below the current Threshold setting (indicates
that satellite signal has been lost). The SEARCH DELAY parameter sets the amount of delay, in seconds that the
MXP will wait after AGC has fallen below the threshold value before it starts a search. Below are the choices of
patterns that each satellite can be set to.
You configure the dimensions of these patterns MXP to use this pattern by using the Search Increment and Search
Limit parameters on the Satellite Configuration page.
11.1.1. Default “Spiral” (Box) Search Pattern
The factory default search pattern in the MXP is a “Spiral” pattern.
When a search begins;
The antenna will then search up in azimuth one Search
Increment, search up one Search Increment in elevation,
search down two Search Increments in azimuth, search
down two Search Increments in elevation, etc until Search
Limit is reached. When the end of the search pattern is
reached, the MXP will retarget the antenna to the calculated
Azimuth and Elevation position of the desired satellite (start
point).
If the desired signal is found (AND network lock is achieved
in the satellite modem) at this position, or anywhere within
the search pattern, the MXP will terminate search and go
into Tracking mode. If the desired signal is not found the MXP will wait SEARCH DELAY seconds and then
begin the search pattern again. This cycle will repeat until the desired satellite signal is found or the
operator intervenes.
11.1.2. Inclined Orbit Search Pattern
Some older satellites, in order to save fuel to keep them exactly positioned over the Equator, are in an
inclined geosynchronous orbit. The satellite remains
geosynchronous but is no longer geostationary. From a fixed
observation point on Earth, it would appear to trace out a
figure-eight with lobes oriented north-southward once every
twenty-four hours. The north-south excursions of the
satellite may be too far off the center point for a default box
search pattern to find that satellite at all times during the 24
hour period.
When a search begins;
Initially the antenna will go to a calculated position that is
half of SWEEP INCR degrees above, and perpendicular to, the
satellite arc (along the same angle as polarization for the
desired satellite). This position is the “Start” of the search
pattern in the graphic above. Then the antenna will drive
down along the polarization angle SWEEP INCR degrees, step one Search Increment to the right (parallel
to the satellite arc), search up along the polarization angle SWEEP INCR degrees, step two Search
Increments to the left, search down, etc expanding out in the search pattern until Search Limit is reached.
When the end of the search pattern is reached, the MXP will retarget the antenna to the calculated
Azimuth and Elevation point.
If the desired signal is found (AND network lock is achieved in the satellite modem) at this position, or
anywhere within the search pattern, the MXP will terminate search and go into Tracking mode. If the
desired signal is not found the MXP will wait SEARCH DELAY, then target the antenna to start point
EAR Controlled - ECCN EAR99