Main Features of WorldNet DAMA Systems

WorldNet DAMA systems offer toll-quality voice, facsimile and data services in areas with little or no telecommunications infrastructure. Users in the world’s most remote locations can access local and international telephone and data services through inexpensive earth terminals and low cost-per-minute satellite connections. Enhanced services such as video conferencing, data trunks and high-speed Internet access are being provided as well.

WorldNet terminals or Very Small Aperture terminals (VSAT’s) are made up of modular building blocks that can be configured of a vide range of services and capacities:

• DAMA modems provide dial-up telephone and data services on satellite channels assigned by the Network Control Center (NCC), when a user requests a circuit. NCC provides powerful circuit management features for seamless integration into the PSTN. Automatically switched redundancy ensures the highest system reliability.
• Modem shelves are pre-wired for up to 11 plug-in DAMA modems. A built-in monitor and control interface (M&C) supports external equipment alarms. Modems operate in two modes: traffic and remote control channel modem (RCCM). In traffic mode modems provide telephony and data service through subscriber, RS232 data, and PSTN trunk interfaces. High-speed data modems and video receivers can be connected at70 MHz and L-band IF. In RCCM mode modems communicate with NCC on control channels. Modems support both traffic and RCCM operating modes, and can switch between modes as required.
• RF Outdoor Units (ODU) are antennas feed-mounted, operate in C- and Ku-band, and deliver 2 Watts of transmit power. More power is available with booster amplifiers.
• TX / RX antennas from all major manufacturers can be used with VSAT’s.

VSAT’s minimize the cost of ownership, as they rarely need scheduled field service visits. The DAMA modems, ODU and remote terminal equipment connected to M&C interfaces are controllable remotely from the NCC. Further, modem software updates can be downloaded remotely over the air. Text messages can be entered on a computer at any site, connected to a modem shelf serial port, and sent throughout the network, with routing to the destination done by NCC computer.

WorldNet earth terminals are ideal for inexpensive solar-power operation in remote locations. The terminals operate from unregulated 12 VDC input voltage. A single-modem terminal with 2 Watts ODU consumes just 50 Watts of power, while a four-modem terminal requires under 100 Watts at 12 VDC. VSAT’s use small TX/RX antennas, typically off-set-fed 1.8 meter type or larger. These antennas usually have elevation-over-azimuth pedestal mounts, and may be bolted onto galvanized pipes installed in concrete or onto non-penetrating mounts.

DAMA circuits operate in star and mesh topology, single hop, with point to point and broadcast connectivity. Subscribers may connect directly to WorldNet modems with ordinary telephones, payphones, facsimile machines, voice-band modems, etc. When connected to PSTN trunks, the modems support multiple signaling protocols. In multi-national networks the modems comply with local standards in each country for signaling protocol and service tones (dial tone, ring back, busy, etc.).