Ross Messages & Data; Transmit Enable Keep-Alive (Tek) Message; Acu Commands - Comtech EF Data ROSS Installation And User Manual

Roaming oceanic satellite server

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ROSS

Satellite Handoff Process

If the handoff state detects a transition point (new service area), the handoff function initiates the

following processes:

1. Disable Transmit – TEK message disabling modulator output power

2. Retrieve the new Service Area information

3. Pushes a new Modem Configuration Parameter file into modem

4. Send the command to ACU to point antenna to new satellite (Orbital Position,

Frequency & Bandwidth)

5. The modem will actively update all new parameters issuing a firm reset (quick

update)

6. Enable Transmit – TEK message enabling modulator output power

7. Enter Normal operating state waiting for modem to receive transmit grant message

from the hub

Note during this process the ROSS may send a TEK message enabling carrier before the antenna

has completed its tracking. In this state the ROSS relies on the hardwired transmit mute control

line from the antenna controller to the modem.

3.1 ROSS Messages & Data

This TEK message is implemented as a watchdog process in the modem and is monitored for

transmit control change or absence status. If the modem detects the (absence) loss of 3 messages

(~15sec), the modem will fail poll reception timing out disabling modulator transmit. The ROSS

continuously sends TEK messages on 5 second intervals to the modem to reset the transmit

enable watchdog countdown timer. If the watchdog is not reset with a TEK message within the

specified interval, the modem will mute its transmitter until a TEK is received again.

ACU commands typically use a proprietary message format. These commands are sent to the

ACU to reposition the antenna to new coordinates. ROSS sends Orbital Position, Frequency and

bandwidth to antenna control commanding it to resume tracking to new satellite location. The

ACU processes the orbital position into Azimuth and Elevation units calculated through the

current GPS coordinates. The frequency and bandwidth focuses the signal track algorithms on a

specific carrier typically the new service areas hub TDM carrier allowing the antenna signal

processor to peak on identified carrier. The modem demodulator lock signal is offered up to the

ACU through hardwire or soft-decision for final peak signal track and confirmation of satellite.

Comtech EF Data, Vipersat Products

MN/13070

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