Common Ground Station

by Colonel Ted Cryblskey  (USA, Retired) and Major John F. Beck

The Army is in the midst of massive changes, organizational transitions, and equipment fieldings to support digitization and information-age warfare concepts. A significant challenge is to see through the depth of the battlefield and fuse single-discipline sources analo- gous information to provide the commander with situational awareness and information dominance over opponents. The Joint Surveillance Target Attack Radar System (Joint STARS) Common Ground Station (CGS) will furnish com- manders from brigade through echelons above corps (EAC) with a compact, HMMWV- (high-mobility multipurpose wheeled vehicle) sized focal point to concentrate the power of the Joint STARS radar system, unmanned aerial vehicles (UAVs), and national- and theater- level sensors.

During the recent Task Force XXI and Division XXI Advanced War-fighting Experiments (AWEs), the exceptional performance of the Joint STARS system was singularly critical to the success of U.S. forces. Joint STARS, and its evolving ground station, have par- ticipated in nearly every major U.S. military operation since its first deployment supporting coalition forces in Operations DESERT SHIELD and DESERT STORM. Joint STARS illuminates the battlefield for the commander, and the CGS displays that battlefield in easy-to-assimilate graphic views.

The ability to access a wide variety of sensors’ output and intelligence broadcasts in near-real-time and to seamlessly provide that preprocessed information to the All-Source Analysis System (ASAS) is a capability undreamed even ten years ago. The Army will field this information age system Army-wide beginning in the fall of 1998 and ending in 2003. Intelligence units from the division and armored cavalry regiment through EAC (Active and Reserve Components) will receive CGSs. With heavy divisions receiving six systems and light divisions receiving five, division commanders will be able to task organize their CGSs to support all facets of the division fight. At corps level, both the intelligence and corps artillery units will receive CGSs.


Developed in the 1980s, Joint STARS allowed North Atlantic Treaty Organization (NATO) forces to gain a comprehensive view of the battlefield, including attacking second echelon forces. In the early 1980s, the U.S. Army had an already aging fleet of OV-1D Mohawk side-looking airborne radar (SLAR) tactical reconnaissance aircraft, unable to fulfill deep surveillance requirements. Consequently, the Army, in concert with the U.S. Air Force and the other Services, defined a new joint surveillance and targeting system to support the Services as well as NATO and Allied nations. In 1982, the Office of the Secretary of Defense (OSD) directed the formation of a Joint STARS Joint Program Office, with the Air Force as the lead Service. The OSD charged the Joint STARS JPO with the development of the airborne portion of the system. They designated the Army as the Deputy Program Manager for the joint system and Program Manager for the ground segment. A contract went to Motorola to develop the Ground Station Module (GSM), which has since evolved into the CGS we are fielding today.

System Evolution and Capabilities

The CGS’s primary sensor feed remains the Joint STARS AN/APY-3 radar system, providing moving target indicator (MTI) and synthetic aperture radar (SAR) imagery. Additionally, the system receives feeds from a host of sensors (see Figure 1). The CGS receives, displays, and disseminates UAV video from the UAV Ground Control Station and secondary imagery from theater and national sources. Signals intelligence data is received from various intelligence broadcast services via the Commander’s Tactical Terminal (CTT); upon fielding beginning in 1999, the Joint Tactical Terminal (JTT)— which transitions to a single, consolidated, integrated broadcast service (IBS)—will replace it.

To disseminate its products, the CGS directly connects to the Army’s digitized command and control (C2) systems, including ASAS, Maneuver Control System (MCS), and the Advanced Field Artillery Tactical Data System (AFATDS). For added flexibility, the CGS will remotely access ASAS over the Mobile Subscriber Equipment (MSE) network. CGS connects to AFATDS via the Single-Channel Ground and Airborne Radio System (SINCGARS) as an over-the-air datalink. To communi- cate directly with Army aviation, the CGS includes an improved data modem (IDM) to forward intelli- gence and receive AH-64D LONG- BOW APACHE radar reports.

The CGS has dramatically improved on early versions of the GSM, originally mounted on 5-ton trucks, and supported by 30-kilowatt (kW) generators. Today, the system is on one HMMWV, supported by a 10-kW generator, and includes the capability for on-the-move operations. A second support HMMWV, with generator, completes the CGS system. Six soldiers, military operational specialty (MOS) 96H (Imagery Ground Station Operator) operate the CGS. The move to the HMMWV configuration provides full mission capability and in- creased mobility, as well as improved air and sea deployability. Through advances in technology and miniaturization, the system has increased in both processing speed and data storage (from 80 megabytes to 78 gigabytes)—a capability several orders of magnitude over that of the earlier GSM configurations. Development of the CGS was one of the Army’s first efforts in spiral development1 and streamlined acquisition.

Building on soldier feedback and experience gained through operational deployments, the CGS has continually improved to meet the increasingly complex requirements of the digital battlefield. The deployments and exercises include Operations DESERT STORM, JOINT ENDEAVOR I and II, the Korean Winter Training Exercise, All Services Combat Identification Evaluation Team (ASCIET), and numerous other field exercises. The Army designed the system using an open architecture, allowing for the rapid insertion of com- mercial off-the-shelf (COTS) technology and components at the system level. This cuts costs, saves time, and allows the system to evolve to meet preplanned product improvements (P3I). Joint reviews with the Army, detailed analysis of current and emerging doctrine, and lessons learned from deployments and training exercises guide the P3I efforts and recommendations.



The CGS, however, is only one part of the Joint STARS system of systems. The heart of the air segment is the modified Boeing 707 E-8 aircraft, mounting a large, phased-array radar. Jointly crewed by the Air Force and Army, the system’s primary mission is to provide dedicated support to ground component commanders. CGS crews interact with the Army element onboard, two 96Hs and one 35C imagery intelligence officer (IMINT area of concentration), passing radar service requests (RSRs) over the dedicated, jam-resistant Surveillance and Control Data Link (SCDL) to modify radar targets and modes. While only 15 CGSs can transmit to an aircraft, an unlimited number of CGSs can receive and disseminate Joint STARS data to the tactical commanders.

Operational Deployments

Although the 93d Air Control Wing (ACW) is still in the process of fielding all 13 E-8 aircraft, the system has proven so essential to commanders that it has already deployed on numerous occasions. Joint STARS deployments date back to the well-publicized participation of the first two prototype systems in Operations DESERT SHIELD and STORM to recent deployments to Bosnia, Southwest Asia, and the Republic of Korea. The Army has fielded Medium (mounted on a 5-ton vehicle) and Light (HMMWV-mounted) GSMs in Europe, Korea, and with U.S. Army Forces Command (FORSCOM) to receive Joint STARS imagery. As the fielding of CGSs progresses, all legacy GSMs will be retired.

System Training

Considering the complexity of the system and the relatively high cost of aircraft operation, support for initial entry as well as sustainment training is an important consideration. The Joint STARS CGS trainer provides the U.S. Army Intelligence Center and Fort Huachuca with the capability to replicate the functionality of the CGS and it offers a realistic training capability for initial entry operators and maintainers. The trainer uses the core software from the CGS system and makes maximum use of COTS hardware and software. The CGS trainer can operate in the distributed interactive simulation (DIS) environment. Plans for the system include linking with the 93d ACW operational base to provide realistic simulations and to aid in ground and aircrew training.

For units with fielded CGSs, embedded training support allows the unit to train for and participate in both Warfighter exercises and other simulation-driven exercises. The system will directly receive and display Corps Battle Simulation (CBS) data. Additionally, operators can input the saved data from prior simulation-driven exercises to their CGSs to focus their training on specific tasks and events. With P3I upgrades, CGS will support training and simulation capabilities for crews, battle commanders, and their staffs.


The Common Ground Station has proven to be a critical tool for situation development and targeting. Joint STARS and the CGS provide commanders at all echelons with a common, near- real-time, integrated view of the battlefield. The system continues to evolve, capitalizing on direct user feedback and the CGS open-system hardware and software architecture. The Joint STARS CGS system is the first joint service, multisensor tactical system that provides commanders at all echelons a real-time, situational awareness and targeting capability. It is important for MI leaders to understand the extensive operational and exploitation capabilities of the CGS and its associated workstations as well as to realize its potential for the commander.


1.  For a good explanation of spiral development, see Endnote 2 in Colonel Elliott’s article that begins on page 5.

Colonel Cryblskey is currently the Director for Army Programs, Motorola Systems Solutions Group. He was the U.S. Army Training and Doctrine Command (TRADOC) System Manager (TSM) Joint STARS from 1985 through 1989 and retired from the Army in 1992. His last position was in the Pentagon as the Director for Aviation and Intelligence Systems, Office of the Assistant Secretary of the Army for Research, Development, and Acquisition (SARDA). COL Cryblskey has a Bachelor of Science degree in Aeronautics from Embery Riddl Unniversity and a Master of Business Management degree fromCentral Michigan University. His telephone number is (703) 413-2508 and his E-mail address is

Major Beck is the System Integrator for Joint STARS CGS and JTT in the Office of the Deputy Chief of Staff for Operations and Plans, Force Development. He has served in a variety of staff and command positions in Europe, Korea, and the Continental United States, including service in the 8th Infantry Division (Mechanized) (8ID(M)), 24 ID(M), and 82d Airborne Division. MAJ Beck has earned a promotion effective early next year. MAJ Beck has a Bachelor of Science degree in Regiuonal Studies from Georgetown University. Readers can contact him at (703) 697-6528, DSN 227-6528, and via E-mail at