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Guardrail Common Sensor

The Guardrail Common Sensor [GR/CS] is a Corps Level Airborne Signal Intelligence (SIGINT) collection/location system that integrates the Improved GUARDRAIL V (IGR V), Communication High Accuracy Airborne Location System (CHAALS), and the Advanced QUICKLOOK (AQL) into the same SIGINT platform -- the RC-12K/N/P/Q aircraft. Key features include integrated COMINT and ELINT reporting, enhanced signal classification and recognition, fast Direction Finding (DF), precision emitter location, and an advanced integrated aircraft cockpit. Preplanned product improvements include frequency extension, computer assisted on-line sensor management, upgraded data links and the capability to exploit a wider range of signals.

GR/CS is an essential member of the Precision SIGINT Targeting System (PSTS). PSTS is a joint-service and defense-agency effort that uses both tactical and national systems to provide a near real-time, precision-targeting, sensor-to-shooter capability. The Guardrail Common Sensor (GR/CS). It is considered to be among the most accurate and timely of signal intelligence (SIGINT) reporting platforms.

GR/CS provides near real-time SIGINT and targeting information to Tactical Commanders throughout the corps area with emphasis on Deep Battle and Follow-on Forces Attack support. It collects selected low, mid, and high band radio signals, identifies/classifies them, determines locations of their sources, and provides near-real-time reporting to tactical commanders. The system uses an integrated processing facility (IPF) which is the control, data processing, and message center for the overall system.

Each system consists nominally of twelve aircraft which normally fly operational missions in sets of three. Up to three airborne relay facilities (ARF)/aircraft intercept communications, noncommunications emitter transmissions, and gather LOB and TDOA data. They then transmit this data to the IPF. The ARF/aircraft also serve as the relay platforms for communications between the IPF and the supported commands. The typical system configuration uses one Integrated Processing Facility (IPF), two or three Airborne Relay Facilities (ARFs), approximately nine (up to a maximum of 32) Commanders Tactical Terminals (CTTs), and an Auxiliary Ground Equipment (AGE) van. Special Purpose Equipment (STE) vans are included for maintenance and troubleshooting.

This system incorporates the Communication High Accuracy Airborne Location System (CHAALS) to achieve target locations for its COMINT system, and CHALS-X, which is a continuation of the project which developed the CHAALS precision location subsystem currently in GR/CS systems 4 and 1. The CHALS-X system provides the targeting capability required to support the Division Commander's requirements to locate and kill the enemy by providing for precise location of High Value Targets (HVTs). Airborne systems mixed with ground based systems will be capable of precisely locating enemy weapon systems and units (regardless of whether the enemy uses conventional or modern radios) producing target locations sufficiently accurate for first round fire for effect by organic artillery. It utilizes the previously developed Time-Difference-Of-Arrival/Differential Doppler (TDOA/DD) techniques and incorporates advances in electronics state of the art and distributed processing to provide for improved capabilities; increases frequency range, adds frequency hopping radios to the target set, and decreases size/weight/power requirements of processing subsystems (3 racks of computer equipment now reduced to two boxes which fit into a standard 19 inch rack). The continued evolution of Target Accuracy Geolocation capability using TDOA/DD is a technology advantage over any other country and has been restricted from release to foreign countries.

GR/CS Targeting accuracy is also provided by the ELINT system. Ground to ground (including CTT) communications links also provide an interface with fixed locations and tactical users. Automated addressing to CTT field terminals provides automated message distribution to tactical commanders in near real time. Planned improvements include expanded COMINT/ELINT collection, LPI capability, embedded training, CTT(3 channel) retrofit, and automated reporting.

The Radio Remote Receiving Set (AN/ARW-83) is commonly referred to as the Airborne Relay Facility (ARF). The ARF consists of equipment installed in a modified Beechcraft Super King Air aircraft with a military designation of RC-12. The ARFs are manned only by the pilots during a mission. ARF mission equipment is remotely controlled by operators in the Integrated Processing Facility (IPF). The Guardrail systems currently in service include the Guardrail V (RU-21H aircraft), the Guardrail Common Sensor Minus (RC-12H aircraft), and the Guardrail Common Sensor (RC-12K/N/P aircraft). Guardrail Common Sensor (GRCS) combines the Improved Guardrail V (IGRV) Communication Intelligence (COMINT) sensor package with the Advanced Quicklook electronics signals (ELINT) intercept, classification, and direction-finding capability, and a Communication High Accuracy Airborne Location System (CHAALS). GRCS shares technology with the Ground-Based Common Sensor, Airborne Reconnaissance Low, and other airborne systems.

GRCS comprises a series of special purpose detecting systems - AN/USD 9B thru E. The GRCS systems are tactical, remotely controlled, airborne mission equipment, and ground-based intercept and emitter location systems. They have an external near real-time reporting capability that can be operated in six modes (local, isolated, remote, interoperable, training, or maintenance/calibration). These systems are assigned to a B company, military intelligence battalion, aerial exploitation, as part of a corps military intelligence brigade.

The GRCS System 1, AN/USD-9C, and System 2, AN-USD-9E, are the latest addition to this family. They have the additional capability to operate worldwide via the GRCS Tethered Medium Earth Terminal (TMET) and the Direct Air to Satellite Relay (DASR) Aircraft (RC-12Q). Other major system improvements are:

• The new UNIX-based work stations.
• Faster (Micro 5) mainframe computers.
• The fiber-optics distributed data interface (FDDI) local area network (LAN).
• The GRCS Data Distribution System (DDS), elementary special signals processing.
• The GRCS Integrated Processing Facility (IPF) rapid deployment capability (two vans minimum vice four).
• The entire system (less aircraft) will be C-130 transportable.

Information is processed and reported to joint consumers via TRIXS broadcast primarily over the Joint Tactical Terminal (JTT) which is a subsystem of the GRCS DDS.

The Northrop Grumman Mission Systems-developed Guardrail Common Sensor System 2, called Guardrail 2000, will be a key component of the Army’s next-generation Aerial Common Sensor System that will provide battlefield commanders with the world’s most advanced tactical surveillance data for the 21st century. Guardrail 2000 is the seventh generation of successfully fielded Guardrail systems over the span of 29 years. Previous versions have been used to provide enemy location information during Desert Storm and to support the Bosnia peacekeeping effort. The system, comprised of a twin-engine Beechcraft airplane and a ground station that remotely controls the flow of intelligence data, forms the foundation for the Army Corps intelligence collection and serves as a critical element of the national intelligence collection infrastructure.

HISTORICAL BACKGROUND:

Jun 84 Contract awarded for GR/CS Systems 3 and 4.

Dec 88 GR/CS (minus) System 3 fielded to Korea.

Jun 89 AC-12K Production award (System 1).

Aug/Sept 90 GR/CS Systems 1 and 2 IPF and ARF Production contracts awarded.

Aug 91 GR/CS System 4 fielded to USAREUR.

Apr 94 GR/CS FY94-99 Program and Acquisition Plan approved by HQDA.

Aug 94 GR/CS System 1 Fielded to FORSCOM.

REQUIREMENTS DOCUMENT: ROC, 1 Oct 84, updated Nov 85 and revised in Apr 92.

TYPE CLASSIFICATION: GR/CS System #1 type classified LP.

SYSTEM SUMMARY

PRIME CONTRACTOR: ESL (Sunnyvale, CA)

Beech Aircraft (Wichita, KS)

SUBCONTRACTORS:
ESL; Sunnyvale, CA
Beech Aircraft; Wichita, KS
ESCO; St. Louis, MO
IBM; Owego, NY
UNISYS; Salt Lake City, UT

Deployment

One GR/CS system is authorized per Aerial Exploitation Battalion (AEB) in the MI Brigade at each Corps. Guardrail provided collection coverage along the inter-German border from 1972 through 1990, in Korea from 1974 to the present, and in Central America from 1983 through 1994. Two systems deployed to Southwest Asia during Operations DESERT SHIELD and DESERT STORM. GRCS (Minus) was fielded to Korea in 1988. The first GRCS system was fielded to Europe in 1991, and the second was fielded to XVIII Corps in 1994 with a remote relay capability that allowed forward deployment of aircraft while the ground processing facility remains in CONUS. As of May 1996, one system remained in Korea, one system was in Europe supporting Operation JOINT ENDEAVOR, the XVIII Airborne Corps system had deployed in support of the combined exercise Atlantic Resolve, and the fourth and final GRCS system is in the Engineering and Manufacturing Development phase in California was fielded in FY97.