Digi M10 - Manual (Page 17)

Digi m10 Technical Overview
Digi International, Inc. © 2009 Page 17 of 26
3.13 GES-to-Satellite Channels
The RF links that connect an ORBCOMM Gateway GES to an ORBCOMM satellite use a single
57.6-kbps uplink and downlink channel that uses the TDMA protocol. This protocol permits
simultaneous RF links between a single satellite and several GES installations within the satellite
footprint. It also provides a virtually seamless hand-over of a satellite from GES to GES under the
centralized control of the GMSS.
3.14 GES-to-GCC Channels
GES-to-GCC links will operate over 56-kbps or 64-kbps data lines. A typical installation consists
of a Channel Service Unit/Data Service Unit (CSU/DSU) with a V.35 interface at both ends.
TCP/IP IEEE 802.3 (Ethernet) packet routers, which provide link layer internetworking, connect
these interfaces to the GCC and GES facilities. The GES process communicates with the GMSS
process using TCP/IP UDP packets.