TRW has delivered a lighter, more capable version of the low data rate (LDR) communications payload it is producing for the Department of Defense's ultra-secure Milstar satellite communication system.
The "new and improved" LDR-4 payload, delivered to Lockheed
Martin Missiles & Space Co., reflects payload and manufacturing
process improvements that TRW has introduced to the program since the
late 1980s. It includes a new digital signal processor that's less
than half the size and weight of the analog unit it replaces, enhanced
memory management capabilities and a new, lighter-weight antenna
steering assembly.
The Milstar communications payload is the hardware that performs
the satellites' unique onboard processing and signal routing
functions. LDR-4 is the fourth of six payloads that TRW is producing
under contract to Lockheed Martin, the Milstar satellite prime
contractor. It will be integrated by Lockheed Martin into the fourth
Milstar satellite, which is scheduled for launch in 2000.
"This new payload is a good example of our commitment to using
technology advancements to increase the operational utility and
reliability of the Milstar satellites," said Dave Vandervoet, vice
president and general manager of TRW's Telecommunication Programs
Division. "We're proud of our record for increasing the payload's
capabilities while decreasing the program's overall schedule and cost
risk."
In addition to smaller, lighter hardware, the LDR-4 payload also
takes advantage of a new initiative developed by TRW to streamline the
process used to integrate and test the payload's three spot beam
antennas.
Paul Borzcik, TRW's Milstar program manager, explained: "Up
through LDR-3, we would integrate and test (I&T) the payload's three
spot beam antennas piece by piece on the actual payload. Since the
antennas attach to the outside of equipment panels, we couldn't do
this work until we'd integrated and tested all the hardware inside the
spacecraft and closed up the equipment panels for the last time."
To save time and to simplify future testing of the payload, a
team of TRW mechanical engineers developed a new process that allowed
the company to integrate and test the antennas separately from the
payload.
"This simple change allowed us to perform several key I&T tasks
in parallel, rather than in series," said Borzcik. "This new way of
building the payloads will streamline both the payload integration
process at TRW and the satellite integration process at Lockheed
Martin."
Under current Pentagon planning, the Air Force will launch a
total of six Milstar satellites. The first two satellites, launched in
February 1994 and November 1995, respectively, are known as Block I
satellites. They carry the TRW-built LDR payload.
Milstar satellites 3 through 6, which are designated Block II
satellites, carry both the LDR payload and a new medium data rate
(MDR) payload that expands Milstar's tactical communications
capabilities. TRW provides the digital subsystem and antenna
subsystems for that new payload, which is being integrated for
Lockheed Martin by Hughes Space & Communications Co.
The Department of Defense's Milstar system includes a
constellation of ultra-secure communications satellites in
geosynchronous orbit, and a family of fixed-site, mobile and
man-portable terminals.
Operating primarily in the extremely high frequency (EHF) and
super high frequency (SHF) bands, Milstar provides secure, survivable
communications among the National Command Authority and Army, Navy and
Air Force users anywhere in the world, day or night, under any level
of conflict.
