Exact Clocking in Satellite and Defense Networks

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Ensuring Exact Clocking In Defence and Satellite Networks

Whether your application is narrowband or broadband, symmetric, asymmetric or uni-directional, the Metrodata AP3000 Access Processor can be used to connect ATM switches, encryptors and satellite modems together.

The clocking capability of the Access Processor range

The Metrodata AP3000 has been developed for interfacing satellite modems with terrestrial networks. Further uses of the AP3000 included backhaul / reachback of asymmetric satellite connections over leased lines, and backhaul / reachback of HSSI/ECL over fiber.

The AP3000 is part of the modular Access Processor product range which can provide speed, interface and protocol conversion between incompatible network products. We can convert ATM to non-ATM, ATM to ATM (e.g. DS3 to E3), ATM to fiber, ATM to serial, ATM to WAN, Ethernet to WAN, Ethernet to G.703, Ethernet to serial, Ethernet to fiber, serial to fiber, fiber to fiber and WAN to serial.

The real strength and competitive advantage of the Access Processor product range is in the flexible serial interface modules.

For backhaul / reachback applications serial interface modules are available which support flexible clock rates to 1bps granularity, and which can lock onto incoming clocks from the satellite modems:

  • EIA530 (up to 20Mbps)
  • HSSI (up to 100Mbps)
  • ECL (up to 100Mbps)
  • LAN (up to 100Mbps)
  • ASI (up to 52Mbps)

Terrestrial telecoms interfaces can also be integrated and transported using circuit emulation: T1, E1, E2, E3 and DS3.

For interfacing to serial satellite modems and radio relay systems ATM cell bearing serial interface modules are available which can lock onto incoming clocks from the satellite modems and so operate at whatever speeds they are told to:

  • EIA530 (up to 20Mbps)
  • HSSI (up to 100Mbps)
  • ECL (up to 100Mbps)
  • ASI (up to 155Mbps)

Native ATM interfaces at terrestrial telecoms rates are also available: E1, E2, E3, DS3, OC-3/STM-1.

All interface modules support hot swap operation and can be used across the entire Access Processor range.

Flexible data rate networks for Federal applications

Federal networks tend to be end-to-end networks which are designed to transport a particular application. For example, wireless technology might be used between the field unit and the terminal, with satellite technology used to connect the terminal to the main terrestrial based network, which typically would be ATM based.

ATM is a convenient networking technology in US DoD networks as it can aggregate multiple different links and bandwidths into a single network infrastructure. However, the majority of ATM vendors have equipment designed to work in a fixed rate environment. simply supporting fixed rates such as E1, T1, E3, DS3 and OC-3. Very few of these switches offer serial interfaces that are "flexible", often only offering Nx64kbps clock rates at relatively low speeds. Whereas satellite and wireless technologies often use serial interfaces at high speeds and using flexible transmission rates.

Metrodata realised that there was a need to offer complete flexibility of data rate, e.g. 9.163 Mbps inbound and 322.231 kbps outbound.

Why such weird rates? Because that was the exact amount of bandwidth required to transport the application, its encryption overhead and potentially an FEC overhead as well, and when your transmission medium is  via satellite or wireless then it may not be possible and it certainly wouldn't be efficient to support convenient terrestrial data rates.

Metrodata provide the ability to integrate the terrestrial ATM network with the exact data rates used by the application, providing complete flexibility of data rate, serial interface and ATM interface. By supporting exact clock rates and flexible clocking modes, Metrodata products within a tactical/federal environment can ensure that 100% data integrity is achieved. With improved data integrity, more accurate decisions can be made, leading to better results in the field.

This technology is particularly useful in Unmanned Aerial Vehicle [UAV] Networks and Rapid Deployed/Field Networks.

Why the Metrodata Access Processor is a strategic product

The Access Processor platform from Metrodata is a strategic product, due to its flexible data rates and clocking modes, as has the following features:

  • ATM connectivity at E1, E2, E3, DS3 and OC-3 rates
  • Fiber connectivity via multimode, singlemode, short haul and long haul fiber interfaces
  • Serial connectivity using EIA530, HSSI, ECL and ASI interfaces
  • Serial data rates with 1bps clock granularity and the ability to slave clocking off other equipment
  • ATM to serial conversion, serial to ATM conversion
  • Ethernet, IP, voice and video data streams are also supported

With the Access Processor we provide connectivity between:

  • ATM switches, ATM access devices and ATM concentrators
  • Low speed synchronous serial equipment - e.g encyrpters
  • Serial satellite modems at low and high speeds
  • ATM encrypters
  • Serial, link, bulk and trunk encrypters
  • Serial applications and fiber

These features are the "building Blocks" of Federal networks, and some of these features are inherent in almost all tactical/military systems.

Often these "Blocks" cannot be fitted together, because of an incompatibility between their interfaces, protocols or clock/data rates, which is where Metrodata can help. Our equipment basically provides the "cement" between the blocks, removing interface connectivity issues, optimising the use of specific protocols and resolving clocking problems.

For further information click on the Access Processor link.

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