COBHAM Sea Tel 9711-56 IMA C Band, Installation Manual

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Sea Tel 9711-56 IMA Configuring The Satellite Modem Interface.
11-3
EAR Controlled - ECCN EAR99
11.1.4. Modem I/O – Custom Settings
Use: The individual Modem I/O selections allow the user
to manually define the expected driver (output) and
detector (input) circuit(s) as well as positive satellite ID
functionality between the MXP and the satellite modem.
Selection Type: Mutually Exclusive Radio Buttons
Options : Lock Input: On or Off, Polarity, 12V Pull up.
Block Output: Polarity and 12V Pull up
Notes: The lock input and Block output radio button
selections may only be modified if the Modem Type “Custom” Modem Type has been selected.
If any of the other Modem Types are selected, the Lock Input and Block Output radio buttons are
predefined for you by software and therefore become read only. This is evidenced to the user by
disabling the selections, see image to right for an example of this.
11.1.4.1. Modem I/O – Lock ON/OFF
Use: The Modem I/O Lock Input “ Lock” selection defines whether or not the MXP will use
positive satellite ID functionality.
When OFF, the system will simply use the tracking receiver settings and the subsequent
AGC from the receiver to track an acquired satellite. This may be the desired satellite or it
may be an adjacent satellite that was acquired during a search for the desired satellite.
When ON, the system must get AGC and ALSO receive a network lock logic signal from the
modem to continue tracking the acquired satellite. This prevents tracking the wrong
satellite and verifies that the antenna is in fact on the desired satellite (to get network lock
from the modem the antenna must be on the correct polarity of the correct satellite). If
during a search an adjacent satellite is found, good AGC from the tracking receiver will cause
the system to initially track/peak this satellite but be waiting for a network lock signal from
the satellite. If the lock signal is not received within 30-40 seconds, that system will return
to the search track line and resume searching for the satellite which provides AGC & Lock.
Lock Input settings below MUST be set correctly for this functionality to work properly.
Selection Type: Mutually Exclusive Radio Buttons
Options : Lock ON or OFF.
Notes: Modem Type “Custom” must have been selected to allow changes to these settings.
Setting Modem Lock to “ON” will enable the positive satellite ID feature whereas setting
modem Lock to “OFF” disables the feature. With the exception of the some calibration
procedures (ie during Cross-Pol isolation and 1dB compression tests) it highly recommended
to leave this setting to ON. By doing so, you eliminate tracking on adjacent satellites for any
extended amount of time (typically 30-40 seconds)
11.1.4.2. Modem I/O – Lock Input – Polarity
Use: The Modem I/O Lock Input Polarity selection defines whether the hard lined wire input
provides a logic level high or logic level low as indication of Positive Satellite ID (RX Network
Lock indication).
Selection Type: Mutually Exclusive Radio Button
Options : Polarity Low or Hi.
Notes: Modem Type “Custom” must have been selected to allow changes to this setting.
You must refer to your satellite modems manufacturers written specifications for its
nominal receive lock indication output. Example if you have a satellite modem that provides
a nominal 5VDC output when in a NON-Locked condition (off satellite) and 0Vdc when in a
locked condition (on satellite), you would set Polarity to “Low”.
If your modem provides a continuity based output, short to ground is Low, and Open is
High. If your modems output is continuity based logic the Voltage must be set to 12V and