Mission Data Transmitted Successfully With Network Gateway

April 1, 2012

In the 1990s, when laying the groundwork for its missile defense shield, the Pentagon realized that if it wanted to provide an effective defense against ballistic missile attack, it needed to create a quick and efficient method of detecting and tracking enemy launches. In other words, it needed to build a highly capable constellation of high-orbiting infrared satellites that would serve as the primary watchtower for the entire Ballistic Missile Defense System.

Operational diagram of the Wideband Isochronous Network Gateway (WING).

Now called the Space-Based Infrared System-High (SBIRS-High), it replaced the current Defense Support Program (DSP) satellites, which provided early missile warning information for more than 30 years.

Administered by the Air Force Space Command, the SBIRS-High constellation includes four geosynchronous earth orbit (GEO) satellites, two highly elliptical earth orbit (HEO) payloads, and associated ground hardware and software. The four GEO satellites in the constellation keep a fixed position with respect to the equator, while the two HEO spacecraft orbit the poles in elliptical patterns, enhancing the GEO satellites’ field of vision. As compared to the DSP system, SBIRS-High has greatly enhanced sensor flexibility and sensitivity. Spacecraft sensors cover short-wave infrared like their DSP predecessors, and also provide enhanced mid-wave infrared and see-tothe- ground capabilities. SBIRS-High satellites detect objects that are much cooler and dimmer than those tracked by DSP satellites, increasing the overall effectiveness of SBIRS-High and the entire missile defense shield.

The Challenge

To support the SBIRS-High program, the Air Force Space Command needed to implement an Asynchronous Transfer Mode (ATM) wide-area ground network for transport of mission telemetry, command, and payload data. Initially, during spacecraft integration and test, the WAN would connect three nodes: the main processing site in Colorado, the SBIRS-High payload manufacturing facility in southern California, and the spacecraft bus manufacturing facility in northern California. Post-launch, similar ground equipment would be employed for ground data transport between SBIRSHigh remote ground stations and the Mission Control Station, located at Buckley Air Force Base in Colorado.

The challenge was to provide equipment to manage transmission of mission data across the SBIRS-High WAN. The Air Force needed to packetize 100-Mbps serial high-rate wideband isochronous satellite payload clock and data for transmission across the ATM WAN, then reserialize the stream from incoming ATM AAL5 Protocol Data Units (PDUs) at the termination node.

The Solution

The commercial-off-the-shelf (COTS) Wideband Isochronous Network Gateway (WING) from CVG-Avtec (Chantilly, VA) was chosen for the SBIRS-High program. WING integrates support for ATM as well as IP networks. At the source, a WING transparently packetizes and transfers a wideband, isochronous serial data stream across an ATM or IP WAN at rates up to 400 Mbps. At the destination, a second WING receives the ATM PDUs or IP packets sent by its counterpart, and can identify and fill missing PDUs with a user-specified fill pattern. The data is then retransmitted out of the destination WING’s high-speed serial interface at a fixed rate, or at the same rate that it was originally received (via automatic rate tracking).

Because WING exceeded the requirements of the SBIRS-High ground network in terms of speed, functionality, and robustness, Avtec was able to meet the customer need without hardware or software customization.

This article was contributed by CVG-Avtec, Chantilly, VA. For more information, Click Here