Jane's Radar and Electronic Warfare Systems 2001-2002


Silent Sentry Detection System
-------------------------------

Type
~~~~
Passive radar-type detection system. 

Description
~~~~~~~~~~~

The Lockheed Martin Mission Systems (LMMS) Silent Sentry passive detection
system utilises a radar-type reception and processing chain to determine air
target location from the Doppler shift of echo signals produced when aircraft
are illuminated by commercial Frequency Modulated (FM) radio or television
transmissions. System architecture comprises Lockheed Martin proprietary, high
dynamic range receivers, Silicon Graphic-sourced Challenge L commercial
processors (with 12 GP engines), Autometric-sourced software and a phased-array
antenna. Functionally, the system is initialised by cataloguing the 50 to 800
MHz band commercial transmitters in its area and establishing their location
and parameters. As noted previously, target location is then determined by the
Doppler shift in the reflected signal from the object under surveillance.

Status
~~~~~~

As of this edition, Silent Sentry is understood to have been in development
since the early 1980s. By late 1998, the system is reported to have been able
to detect 10 m2 radar cross section targets at ranges of up to 180 km using a
single FM illumination source. LMMS also claims that the equipment can track in
excess of 200 targets with formation spacings of as little as 15 m. As of this
edition, sources suggest that the system has been modified to make use of three
FM illuminators and 28 GP engine Challenge XL processors in order to facilitate
3-D target location. An operational Silent Sentry architecture is described as
offering a 3-D tactical display, as utilising up to six FM illumination sources
and as being configurable for fixed-site or deployable applications. The
antenna array used in such a system is noted as measuring 2.3 to 2.5 m2.

Contractor
~~~~~~~~~~
Lockheed Martin Mission Systems 
Gaithersburg, Maryland.