Hughes Network DirecWay DW4020, User Manual

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Frequently asked questions
5. What is Automatic Cross Polarization (ACP)?
The ACP feature provides transmit satellite dish pointing information to your
installer and automatic satellite dish revalidation. This ensures your satellite
dish remains aligned.
Satellite systems with transmit capability — the ability to send data directly to
the Internet via the satellite without a telephone connection — need to be
checked periodically to be sure that the satellite dish alignment remains correct.
Satellite dishes may become misaligned because of structures settling,
unauthorized tampering or, more commonly, high winds.
If the satellite dish alignment is not correct, transmissions from your equipment
might interfere with other users of the satellite, and your signal might be weak.
The means used in the satellite industry to check transmit satellite dish
alignment is
cross polarization co-polarization isolation measurement or
cross pol for short. Until recently cross pol measurements could only be made
by satellite maintenance personnel.
Your ACP-equipped system can enter a test mode and initiate an automatic cross
pol test session between your satellite dish and the Network Operations Center
(NOC). The test is performed by firmware in the satellite equipment, not on
your PC. Since your PC is not involved, the test cannot compromise the security
of your system.
If your equipment fails a periodic test, you will be contacted to schedule a
service call. Other ACP features such as the Antenna Pointing - Transmitter
screen (Figure 41 on page 36) are utilized by satellite service personnel to
increase the accuracy of satellite dish alignment.