Square Peg Communications Inc. supplies Remodulators for Dual Satellite Operation of Inmarsat-C

February 1, 1996

Square Peg has supplied a modified version of its SCPC channel unit model SCU-2R to satisfy Inmarsat’s requirement for dual satellite operation of Inmarsat-C. Thirty-one of these Standard-C Remodulator Unit (CRUs) have been delivered and are being installed at Inmarsat Land Earth Stations (LESs) world wide.
The traffic flow is as follows:

• Traffic is generated at the originating LES in Std-C format and is presented to a CRU at a 70 MHz ± 18 MHz IF frequency

• The CRU demodulates the data and remodulates it on an independent IF frequency

• The signal is carried over the primary satellite to a turnaround LES, where it is presented to a second CRU at IF

• The second CRU demodulates the data and remodulates it in Std-C format on an independent IF frequency

• The signal is carried over the secondary satellite to the Std-C terminals

The Std-C modulation format is unfiltered BPSK at 1200 bps, while that between CRUs is rate ½ coded DMSK at 2400 bps. The function of a CRU (BPSK to DMSK or vice-versa) is operator-selectable. The unit can also be operated in BPSK to BPSK or DMSK to DMSK mode.

Photos of front and rear panel.

 
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