Chapter 2

Air Defense Artillery Control Systems

The exchange of information between missile fire units and command posts must be instantaneous. Army air defense artillery units require timely and continuous information on the location of friendly and hostile aircraft. Immediate collection and dissemination of target data are required to insure rapid fire unit response and concentration of effort directed toward the enemy threat. To provide air defense artillery commanders with this required capability, the Army employs electronic command, control, and coordination systems (CCCS) and associated equipment.

Modern CCCS are essentially specialized automatic data processing systems and, as such, have shared in major state-of-the-art advances over the past few years. As the vacuum tube gave way to the transistor, with its reduced size, weight, and power requirements, so the transistor circuits of today have been replaced by microminiaturized integrated circuits in new CCCS. Thus, the challenge of the ever-increasing air threat is being countered by the most reliable and effective command, control, and coordination equipment possible.

The battery integration and radar display equipment (BIRDIE) system AN/GSG-5 (figs 33 and 34) was developed to provide a compact, reliable, and transportable system to integrate Nike Hercules batteries. Through semiautomatic ground environment (SAGE) direction centers, and backup interceptor control (BUIC) stations in certain operational modes, BIRDIE systems are integrated into the overall air defense of CONUS.

Radars used with the AN/GSG-5 system include defense acquisition radars AN/FPS-36, AN/FPS-69, or any acquisition radar with a pulse rate of 200 to 400 pulses per second. The radar furnishes target slant range and azimuth, hut no height data, to the AADCP. The radar has IFF equipment which is used as an aid to identification.

The AADCP contains display equipment, computer and data storage facilities, voice communications, and power and testing equipment. The situation display console has controls and indicators that enable the controller to enter target identity, position, and velocity into the memory system. The controls and indicators also enable the controller to make or erase target assignments to batteries and to dump data from the memory system. The plan position indicator (PPI) displays video from the radar, local track symbols, SAGE/BUIC track symbols, battery return symbols, and other symbols as selected by the controller.

Figure 33. Battery integration and radar display equipment (BIRDIE) system AN/GSG-5.
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Figure 34. AN/GSG-5 (BIRDIE) system.
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The AN/GSG-5 can integrate a maximum of 16 Nike Hercules batteries and display approximately 30 SAGE/BUIC and local tracks plus 16 battery returns. The automatic data link (ADL) permits automatic transmission of digital data between BIRDIE and SAGE/BUIC. The battery data link (BDL) transmits data from BIRDIE to the batteries. The batteries transmit data back to BIRDIE and all other integrated batteries. The computer and storage system allows semiautomatic tracking of targets up to a speed of 2,250 knots.

The data converter AN/GSA 77, described in detail later in this chapter, which has replaced older battery terminal equipment in all ADA command, control, and coordination systems, links the missile battery with the BIRDIE system.


The Missile Monitor (AN/MSG-4) command, control, and coordination system was developed by the US Army to coordinate the fire of Nike Hercules and Hawk missile batteries with the army in the field. These systems make it possible to observe and influence the entire air battle from the widest viewpoint so separate actions of numerous batteries can be supervised and unified into an integrated defense.

The AN/~IISG-4 system is composed of two basic subsystems: the AN/MSQ-28B or AN/MSq-56 sybsystem located at group-brigade level, and the AN/TSQ-38 subsystem (which is helicopter transportable), located at battalion and battery level.

The AN/MSQ-2BB subsystem (fig 35) includes a frequency- scan, three -dimensional radar AN/MPS-23A, a radar data processing center (RDPC), and a weapons monitoring center (WMC). The AN/MPS-23A radar provides target detection, furnishing range, azimuth, and elevation angle of the target. The antenna rotates mechanically in azimuth and scans electronically in elevation. The AN/MPS-23A is equipped with IFF equipment. The RDPC (fig 36) provides initial display of targets, a means for interrogation of targets, and automatic tracking. Tracking is accomplished at six detector-tracker (DT) consoles in the RDPC. Height data are observed on two range-height indicator (RHI) consoles. The H, X, and Y coordinates of targets, plus X and Y velocities, are stored as track data and sent to the WMC.

The WMC (fig 37) provides the group/brigade commander with an immediate presentation of the tactical situation at all times. Track marker data are displayed in the form of symbology on weapons monitoring consoles. Battery status also is received from the battery and displayed on these consoles. This combined symbolic and read-out display of information enables the commander to view the entire air battle and make assignments from the WMC to the batteries under his control. The WMC can accept and utilize data from Air Force agencies and adjacent defenses. The Missile Monitor system has the capability of directing more than 30 fire units against more than 150 targets.

The battalion-level component of the AN/TSQ-38 is the battalion operations central (Bn OC) (fig 38). The BN OC gives the battalion commander the capability of either monitoring reference data and the changing status, or making assignments to the firing battery, depending upon the method of control and mode of operation. It links the battalion uith the group WMC and fire units and displays battery status, target video, and symbology on each of two consoles. The electronic search central AN/GSS-1 (or AN/GSS-7) of the battalion is connected to the Bn OC and can furnish radar data to the Bn OC. In turn, the Bn OC can insert these data into the data link, thus providing additional information to all fire units under WMC control in the normal mode of operation.

Figure 35. AN/MSQ-28B subsystem of Missile Monitor system.
Figure 36. Interior view of radar data processing center.
Figure 37. Interion view of weapons monitoring center.

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Figure 38. Battalion operations central consoles.
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The battery-level component used in conjunction with the AN/TSQ-38 is the data converter AN/GSA-77. The data conveaer, which functions as a link between battalion and battery, is a transmitter receiver that permits exchange of data between the battery and other elements of the system. Information which may have originated at the WMC, BnOC, or other fire units is received at the AN/GSA-77 in the form of binary digital data. The AN/GSA-77 converts these data for display at the battery control console. Information originating at the battery is converted to binary digital data by the AN/GSA-77 and sent to the Bn OC and WMC.

The AN/MSG-4 system has six data link switching modes of operation. Only three of these modes--normal, sector, and independent--are used in tactical operations. In the normal mode, the WMC sends reference information and commands through the Bn OC to the battery. The Bn OC monitors, but does not originate, commands to the batteries. In the sector mode, reference information is sent to the Bn OC and the batteries and the Bn OC originates commands to the batteries. In the independent mode, all reference information and commands originate at the Bn OC. The other three modes of operation are used for tests and emergencies.

The primary means of transmitting information, using binary digital data, is by automatic data link. Common carriers of ADL include spiral-$ cable or microwave, but any carrier capable of handling pulses made up of frequencies between 600 and 1875 hertz will suffice.


A new command, control, and coordination system, Missile Mentor(tlN/TSQ-51), has been deployed in CONUS to replace some first-generation CCCS, including all Missile Master systems. This new system is designed on the modular concept, allowing addition or deletion of major functions so that requirements of various defense complexes may be met with reduced operational costs, simplified maintenance, and increased track-handling capability as compared to older systems. Data are automatically exchanged by digital data link and voice communications with all defense elements, including both Nike Hercules and Hawk fire units. This mobile AN/TSQ-51 system requires no equipment air conditioning. The system integrates the operation of surface-to-air missile ADA fire units by acquiring tracks, processing data, and making track assignments to fire units. Each deployment site has a varying number of associated fire units and remote data sources integrated into a coordinated air defense system. Effective air defense command, control, and coordination are sustained by the AN/TSQ-51 gathering and supplying up-to-date, real-time information on the air situation, threat, and weapon availability.

Figure 39. AN/TSQ-51 operations trailer (interior view).
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The AN/TSQ-51 system is comprised of two subsystems, the operations and equipment trailers, which together serve as the Army air defense command post (AADCP), and the remote radar integration station (RRIS). The RRIS, contained in one trailer, can be used to provide radar gap-filler information as well as extend the effective radar range of the defense. The operations trailer (fig 39) contains tracking and tactical display (general purpose) consoles (fig 40) and operations boards. The equipment trailer (fig 41) contains track equipment, including a general purpose digital computer. The major functions performed by the system are target detection, acquisition, identity, track correlation, threat evaluation, fire unitdesignation, and fire unit status monitoring. The system gathers these data concerning its defense area and extends the system coverage by analysis of track data from remote sources; i.e., semi-automatic ground environment (SAGE) system, backup interceptor control (BUIC), RRIS stations, adjacent AADCP's, and surveillance radars. Actions are coordinated for fire units under its command. The system operates in conjunction with standard acquisition radars for local zone coverage. It has automatic and rate-aided manual tracking facilities for keeping data current for local tracks. the operations trailer equipment has been remoted into permanent facilities. Operation and maintenance of remoted equipment are the same except for equipment cooling.

Figure 40. AN/TSQ-5l general purpose console.
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The RRIS (fig 42) consists of one trailer containing tracking display (general purpose) consoles, and a general purpose digital computer that differs from that in the equipment trailer chiefly in its smaller memory capability. Each RRIS nets remotely located radars, and each RRIS can compute data on tracks within its area of coverage and transmit data to the parent AADCP. It also stores and displays data on AADCP-transmitted tracks.

The data converter AN/GSA-77 serves as the battery terminal equipment for the AN/TSQ-51, performing the same functions as it does with the AN/MSG-4 system.

Figure 41. AN/TSW-51 equipment trailer (interion view)
Figure 42. Remote radar integration station (interior view).

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Before any commander can engage an airborne threat, he must know the location of the threat in relation to his unit. The location of the threat is expressed in terms of azimuth, elevation, and range from the unit. In most current air defense artillery command, control, and coordination systems, two types of radars are used to provide these data: an acquisition radar to determine azimuth and range and a height-finder radar to determine elevation. Use of two radars rather than one presents obvious problems; e.g., two radars must be moved in a mobile situation, two radars must be maintained and repair parts stocked for each, and two radars must be emplaced on carefully selected terrain to prevent masking of the height finder radar so that it can cover areas identical to those covered by the acquisition radar.

A three-dimensional (3D) radar can furnish all these data; i.e,, azimuth, elevation, and range. This type of radar utilizes electronic scanning. One of the later classes of electronic scanning radars, the AN/MPS-23 (a component of the Missile Monitor FDS), provides three dimensional search. It supplies target azimuth, elevation angle, and range data simultaneously from a single antenna (transmitter and receiver) channel. The beam scans electronically in elevation while the antenna rotates in azimuth. The antenna frequency-scan operation is similar in principle to that of a slotted waveguide with the microwave energy radiated from the slots combining to form a beam. When the frequency is matched and phased with the distance between the slots, the direction of propagation is straight ahead. If the frequency of the energy is changed, relative phase differences are set up from one slot to the next, changing the direction of propagation accordingly. Continuous phase shifting is achieved by using variable frequency exciters in the transmitter. These exciters can be programed digitally to provide various patterns of beams scanning in elevation. The AN/MPS-23 incorporates moving target indicator circuits that blank out returns from stationary objects. It is capable of azimuth sector scanning a, well as 6,400-mil rotational scan. It provides variable scan rates in elevation and azimuth and uses variable pulse repetition frequencies· The changing radiation frequency gives this radar inherent resistance against electronic jamming.

Another proposed type of 3D radar incorporates many desirable characteristics, such as mobility, compactness, light weight, ease of maintenance, and ability to operate in an ECM environment Electronic equipment is sealed from such ambient conditions as sand and dust, salt spray, rain, and humidity and is cooled by built-in, air-to-air heat exchangers Transportable by helicopter, cargo aircraft, or standard military vehicles, the lightweight 3D radar can be put into operation quickly at remote sites. Rugged, compact design enables the entire system to be packaged in two waterproof inclosures, 6.5 feet by 6.5 feet. The antenna package has a length of 12 feet and weighs 2,300 pounds; the electric equipment shelter has a length of 9 feet and weighs 3,500 pounds.

The antenna inclosure of this radar is uniquely designed for transportability and rapid assembly The pedestal and simplified aZimuth drive system are integral parts of the lower portion of the antenna package, packed in the upper portion of the inclosure are the reflector panels and waveguide lengths. The thin-shelled parabolic reflector is assembled from four structural modules joined with quick-disconnect fasteners. Six men can perform the entire assembly and hookup procedure.


All air defense must start with a knowledge of the attacking forces. As a result, any air defense system must perform an aircraft tracking function which yields information that commanders can use to engage the attacking force. This tracking function can exist either as an integral feature of the air defense system, such as the defense acquisition radar, or by the addition of radars specifically deployed for the purpose of early warning or gap-filling.

The term, radar netting (fig 43), describes the process by which track data derived from several additional or remote radars are gathered at a single center to produce an integrated set of meaningful target information which can be distributed to all air defense elements concerned.

Figure 43. Radar netting concept.
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Radar netting can provide concurrent coverage of a selected area by more than one radar. Each remote radar, independent of central computing facilities, can continue to furnish processed track data to another user even if its primary user is disabled. Another advantage is furnishing jam-strobe tracking or obtaining cross-hearings on a jamming target to determine its position by triangulation.

A radar netting system exchanges data among various radars, surface-to-air missile batteries, and command centers by advanced digital data transmission techniques. The standard operational system consists of the following subsystems: radar tracking station, radar netting unit, and battery terminal equipment.

The radar tracking station (fig 44) is a compact radar data processor which accepts track information from its associated acquisition radar. This track information enters the computer and is updated by manual tracking on the part of the console operator. The computer stores the track data in digital form, which are then made available by data link to any user in the netting system. The user receives position coordinates, velocity components, laid size, identification, track number, and target height.

Figure 44 Radar tracking station (interior view).
Figure 45. Radar netting unit at battalion operations central.

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Incoming track data irom each radar tracking station must be received at the battalion operations central and relayed to the missile batteries as well as to the other radar tracking stations. At the battalion operations central, the radar netting unit (fig 45) acts as a sequencing and distribution device, channeling data from each radar tracking station to the missile batteries through their terminal equipment, to the battalion operations central displays, and to other radar tracking stations.


Data converter AN/GSA-77 (fig 46) is an onsite data processing unit that links the missile battery to its command, control, and coordination system. It provides a means of integrating both Nike Hercules and Hawk units into either the BIRDIE, Missile Monitor, Missile Mentor, or Marine Tactical Data System. Digital commands and target coordinate data, received over automatic data links from the CCCS, are converted into suitable form for use by the weapon system. Battery status and coordinates of the tracked target are encoded into digital form and transmitted to the CCCS for use by the defense commander and retransmission to other batteries of the defense.

Figure 46. Data converter AN/GSA-77.
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Figure 47. Location of AN/GSA-77 in Nike Hercules and Hawk systems.
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While the AN/GSA-77 normally exchanges data with other batteries through the CCCS at the AADCP, it has the capability of communicating directly with adjacent batteries over separate data links. If the AADCPitself is out of action, each battery of the defense receives information on the actions of all other batteries. Upon loss of one or more interbattery data links, the remaining linksare utilized in a manner calculated to maximize information transfer. The various communication configurations are automatically selected by the AN/GSA 77, although this selection may he manually overridden by battery personnel.

The AN/GSA-77 is a microelectronic device which replaced FUIF and CDG. It is mounted within the Nike Hercules director station or the Hawk battery control central (fig 47), requires no air conditioning, and operates on only 178 watts of 400-hertz power. Automatic self-test, semiautomatic fault isolation plocedures, onsite repair by replacement of throw-away, plug-in circuits, and general high reliability of solid-state devices result in a significant increase in operational readiness of air defense artillery units.


The present defense acquisition radars (DAR) have evolved from the early warning radar AN/TPS-1. This radar included only the essentials required to provide early warning information. Similar but not identicalequipment, the SCR-602A, appeared in the military radar inventory during World War II. Later the AN/TPS-1B radar was designed. The addition of moving target indicator circuitsto the AN/TPS-1 produced the AN/TPS-1D, a medium-power search radar designed to detect targets in excess of 290 kilometers. It was first employed bythe Air Force and the Navy.

Subsequent issue of the AN/TPS-1D satisfied the requirement for long-range radars at battalion level in air defense artillery units. In 1957, further improvements were provided by more stable moving target indicator circuits, better vertical antenna coverage, and a better display system which changed the nomenclature to AN/TPS-1G.

To make the AN/TPS-1D and AN/TPS 1G radars more compatible with unit mobility, they were packaged in a metal shelter, They also were assigned a new name, electronic search central AN/GSS-1 (fig 48). In addition to the radar, the shelter contains radio and telephone facilities, IFF equipment, and a manual plotting board. The shelter can be mounted on a 2.5-ton truck and can serve as an emergency battalion AADCP. When the larger 11- by 40-foot tripod-mounted antenna is provided with these radars, the equipment becomes electronic search central AN/GSS-7 (fig 49).

Concurrently, the requirement for a radar with increased range for ARADCOM units resulted in modification of these radars to provide a fixed early warning radar, the AN/FPS-36. This radar employs the 11- by 40-foot antenna, which, with receiver changes, improves the reception of radar returns and extends the range coverage.

Figure 48. Electronic search central AN/GSS-1.
Figure 49. AN/GSS-7 antenna.
Figure 50. AN/FPS-61 radar.

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Further modification of the AN/FPS-36 resulted in the AN/FPS-56 radar. This radar consists of two AN/FPS-36 radars that transmit and receive through a common antenna, thus providing two operating channels and increased reliability. The addition of ECCM capabilities converted the AN/FPS-56 radar to the AN/FPS-61 (fig 50).

The modification of the AN/TPS family of radars did not cease with the development of defense acquisition radars. These same radars are the basis for the development of the alternate acquisition radars discussed in chapter 3.

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Updated July 15, 1998