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Appendix C

Communications

This appendix provides an overview of Patriot communications doctrine and the supporting C4I resources that must be considered in communications planning activities. The Patriot system relies heavily on internal and external data and voice communications. For more detailed information, see FM 3-01.87.

OVERVIEW

C-1. The Patriot communications architecture allows Patriot to integrate with Army, joint, and allied C4I systems in both mature and immature theaters. In a mature theater, Patriot normally integrates as part of an Army air defense brigade at EAC or corps, and may be required to fight in an air and missile defense task force (AMDTF) that includes THAAD and other Army, joint, or multinational systems. In an immature theater, Patriot battalions or batteries may fight in a TF with THAAD as part of an air defense brigade (Patriot batteries may fight without a battalion) or may be required to electronically integrate with joint or allied C4I systems depending on METT-TC circumstances. Figure C-1 shows the basic communication links for Patriot. Note: Depending on the units capabilities communication links may also include TIBS, TRAP, TDDS, IBS, TADIL-A, and voice and etcetera.

Figure C-1. Patriot Communications Overview

Figure C-1. Patriot Communications Overview

BATTALION COMMUNICATIONS

C-2. The Patriot battalion communications networks must provide reliable, real time or near real time exchange of information between dispersed Patriot batteries, higher headquarters, adjacent battalions, and supported units. The communications system must be redundant to provide continuous communications even when the primary system fails. To effectively accomplish the mission, the Patriot battalion must maintain communications that will support—

  • Control of the air battle.

  • Command, administrative, and logistical communications with higher headquarters, subordinate units, and lateral units.

  • Liaison with supported units or the units in whose area the Patriot battalion is operating.

C-3. The Patriot battalion commander is responsible for establishing effective communications. He exercises C2 of organic signal assets through his signal officer. The doctrinal responsibilities for establishing communications are from higher to lower, left to right, and supporting to supported. The battalion uses organic multichannel radio and local wire nets to provide external and internal communications. An organic communications platoon provides multichannel UHF and range extension for the battalion and limited support to the FUs.

EXTERNAL COMMUNICATIONS

C-4. External communications are established with the ADA brigade and adjacent Patriot battalions. The battalion is also capable of communicating with a CRC/TAOC, AWACS, AAMDC, Navy, ADA brigade, and SHORAD battalions.

C-5. Patriot communications provide a capability to communicate with weapon, intelligence, and communications systems external to the battalion. There are two major elements to the communications capabilities. These capabilities provide interservice interoperability for Patriot. The first major element provides Patriot battalions with direct access to tactical digital information link TADIL-A, TADIL-B, and TADIL-J networks through upgrade of the routing logic radio interface unit (RLRIU) and addition of radios. The second major element provides interoperability with the ACUS, which is composed of mobile subscriber equipment (MSE) at corps and below, and of Tri-Services Tactical Communications (TRITAC) equipment at echelons above corps. Intelligence data is received over the Tactical Information Broadcast System (TIBS) on the Commander's Tactical Terminal—Hybrid Receiver (CTT/H-R) unit. The data is forwarded to the ICC and tactical planner workstation.

ADA Brigade

C-6. Communications with the ADA brigade supports air battle C2. It also facilitates administrative, logistical, operational, and intelligence functions. The brigade commander is responsible for establishing voice and data link communications and for providing an ACUS gateway to the MSE network. The connectivity supports voice, and data communications between brigade and the Patriot battalion.

C-7. The brigade maintains a multichannel system between the brigade and subordinate Patriot, THAAD, and SHORAD battalions. The corps ADA brigade is supported by the corps signal brigade, normally with an MSE SEN at brigade headquarters and required resources at the Patriot battalion location. Because the MSEs capability is extremely limited the SEN should be collocated with the battalion TOC.

Adjacent Patriot Battalions

C-8. A Patriot battalion normally establishes UHF multichannel communications with an adjacent Patriot battalion using one of the four links of a CRG. Adjacent battalions exchange engagement operations information using the Patriot digital information link (PADIL) at a data exchange rate of 256 or 512 bits per second over the AN GRC 103 radio. This data exchange rate is needed to ensure high quality fire control and track coordination.

Supported Unit

C-9. Patriot battalions establish voice and data communications with the unit in whose area the battalion is operating. The battalion normally coordinates with the ADA brigade or AAMDC on ADA functions and operates in the Patriot network. The Patriot battalion provides early warning to the supported unit command net.

C-10. Engagement operations communications consist primarily of data communications. However, voice communications complement and supplement data communications. JTIDS is the primary means used for data communications; however, CTT provides linkage to early warning and intelligence networks. MSE and SINCGARS are the primary means for voice communications.

C-11. Force operation communications are essentially the same as used for engagement operations voice. These include—

  • TRITAC.

  • MSE.

  • SINCGARS.

Supporting Unit

C-12. Supporting units establish communications with the supported unit. Normally, the attached direct support (DS) Patriot maintenance company (MC) collocates with or sends a liaison element to the Patriot battalion headquarters. If this is not feasible, the DS Patriot maintenance company enters the Patriot battalion administrative and logistics net. All other units that provide support to the Patriot battalion on an area basis normally establish communications with the Patriot battalion. This includes the S1 and S4 operations.

INTERNAL COMMUNICATIONS

C-13. Internal communications are established with each Patriot FU to support force operations and engagement operations functions. Internal communications facilitate control of the air battle, administrative, intelligence, operations, and logistics functions, using both UHF multichannel and VHF-FM nets.

Multichannel Radio Systems

C-14. Patriot battalions use organic resources to establish multichannel communications with each subordinate battery. To pass real time engagement operations information, automatic data links are established using a multi-routing scheme shown in Figure C-2. If an FU is collocated with the Patriot battalion, it can connect via specialty cable (CX 11230) directly to battalion.

Figure C-2. Battalion UHF Links

Figure C-2. Battalion UHF Links

C-15. Three voice circuits are established over the UHF multichannel network between battalion and batteries. These open circuits allow everyone at each battery and battalion to be simultaneously on line. Each radio is used for the multi-routing of data on the automatic data link circuit PADIL, normally channel 4. An engagement voice circuits established using channel 1, corresponds with party line 1 on the operator's intercom box. Intelligence and radar reporting circuit is established using channel 2 and party line 2 on the Intercom Box. Another circuit is reserved, using channel 3 and party line 3 as a maintenance circuit (not used for control of the air battle). Patriot battery TCAs and battalion TDAs monitor the ADC circuit while the battery TCOs and battalion TDs monitor the higher echelon nets.

C-16. Patriot battery and battalion communications operators use the maintenance net. This circuit is an unsecured channel used to coordinate communications circuits. This circuit is similar to other circuits between the battalion and the ADA brigade.

Battalion Command FM Net

C-17. The purpose of this net is to provide communications for the command function within the battalion headquarters. The stations operating in the net are shown in Figure C-3. This is used as the primary C2 net during movements and as a secondary net when in a static position.

Figure C-3. Battalion FM Command Network Layout

Figure C-3. Battalion FM Command Network Layout

Administration/Logistics, Intelligence, and Operations

C-18. Normally, the UHF multichannel radio system, which provides communications for control of the air battle, also supports other functions. Since the UHF system is operational most of the time, it is also the primary means for the staff to provide C2 of the FU. The number of circuits is limited by the 12 external wire connections at the ICC. These 12 circuits must provide connections to brigade and each battery. Generally, each battery has a minimum of two circuits and will frequently have more. These UHF circuits are connected to switchboards at the battalion and battery.

C-19. The ICC is linked to the battalion TCS and the system maintenance center by a wire network using TA-312s, DNVTs, or LS147s as shown in Figure C-4. This net allows for rapid communications between key elements of the TCS and the ICC. It can be used to cross-tell time-sensitive air battle data such as a change in the airspace control order (ACO). Maintenance support can also be requested without leaving the ICC.

Figure C-4. Battalion Wire Net

Figure C-4. Battalion Wire Net

C-20. The battalion and battery wire net connectivity is shown in Figure C-5. This net is the primary means of communications between battery elements using either DNVTs or LS147 telephones. The switchboard also provides access to a minimum of one circuit to each FU.

Figure C-5. Battalion Local Wire Net

Figure C-5. Battalion Local Wire Net

C-21. A voice and data wire link provides administrative and logistics C2 see Figure C-6 for illustration. The net control station is located at the S1 and S4 van. Every station in the net is secure. The net is routed through the CRG with UHF links to higher and supported units.

Figure C-6. Battalion Administrative/Logistics Net

Figure C-6. Battalion Administrative/Logistics Net

BATTERY COMMUNICATIONS

C-22. Patriot battery communications are comprised of three systems: the battery command net, the FU operations net, and the battery data net. These nets are described below.

BATTERY COMMAND NET

C-23. The battery command net as shown in Figure C-7 is an FM radio net used to exercise C2 of the battery during unit road movements. The 1SG is included in the battery net to help the commander facilitate command and control, during and after movement. The FM radio net also provides backup communications (for FU operations net) after the FU has been emplaced.

Figure C-7. Battery Command Net

Figure C-7. Battery Command Net

FIRE UNIT OPERATIONS NET

C-24. The FU operations net shown in Figure C-8 is a wire net used to exercise C2 of the FU after it has been emplaced. The net control station for this net is the CP. A switchboard in the CP allows the commander to communicate with the 1SG, ECS, the launcher sections, the communications section, maintenance platoon, supply, and other elements. Switchboard connections are diagrammed in Figure C-9.

Figure C-8. Fire Unit Operations Net

Figure C-8. Fire Unit Operations Net

Figure C-9. Battery Switchboard Connections

Figure C-9. Battery Switchboard Connections

BATTERY DATA NET

C-25. The data net in Figure C-10 provides connectivity between the ECS and launchers, and is used to launch missiles and establish missile availability and status. Fiber-optic cables link the ECS to the local launching stations. Data radio transmissions are used as backup for local launchers and as primary for remote launchers. The net is controlled at the ECS by special purpose radio equipment that provides reliable transmission of low-data rate messages over a short path. All command messages originate at the ECS, requiring a slaved response from the LS in the form of a status message. The LS cannot originate data communications. This is the first net established during battery emplacement.

Figure C-10. Battery Data Net

Figure C-10. Battery Data Net

AIR AND MISSILE DEFENSE TASK FORCE COMMUNICATIONS

C-26. The Patriot battalion may be task-organized with THAAD and/or SHORAD units, forming an air and missile task force (AMDTF). The AMDTF uses a variety of communications networks to accomplish its mission. These networks, shown in Figure C-11, include the joint data network (JDN), the joint engagement coordination network (JECN), the joint mission management network (JMMN), and the UHF and other voice nets. The JDN, JECN, and JMMN are JTIDS communications networks that disseminate TADIL-J data messages.

Figure C-11. AMDTF Communication Networks

Figure C-11. AMDTF Communication Networks

JOINT DATA NETWORK

C-27. The JDN is used to disseminate near-real time surveillance and precise participant location information (PPLI). It is used by the AMDTF primarily for exchanging air and missile track data. The specific messages used in AMDTF operations are shown in Figure C-12. These messages are associated with network participation groups (NPGs) 6 and 7. (See CJCSM 6120.01B for a discussion of NPGs and TADIL J messages).

Figure C-12. Joint Data Net

Figure C-12. Joint Data Net

JOINT ENGAGEMENT COORDINATION NETWORK

C-28. The JECN is used to disseminate near-real time engagement coordination information. It is used by the AMDTF primarily to coordinate engagements between Patriot and THAAD. The specific messages used by the AMDTF, shown in Figure C-13, are associated with Patriot external communications.

Figure C-13. Joint Engagement Coordination Net

Figure C-13. Joint Engagement Coordination Net

JOINT MISSION MANAGEMENT NETWORK

C-29. The JMMN is used to disseminate near-real time mission management information. It is used by the AMDTF and THAAD to disseminate commands, engagement status, and ICC/ECS operational status. It also serves as a C2 link with higher headquarters and joint agencies. Figure C-13 illustrates the joint engagement coordination net.

UHF VOICE, ACUS, AND SINCGARS NETS

C-30. The UHF voice net, shown in Figure C-14, provides the primary communications for coordinating AMDTF engagement and force operations activities, including engagement coordination, defense design, firing doctrine, system initialization, and sensor orientation, with task force elements. The area common user system (ACUS) net is also used to coordinate force and engagement operations activities. The single-channel ground and airborne radio system (SINCGARS) net is a FM net used for backup C2 within the AMDTF.

Figure C-14. MSE and Voice Nets

Figure C-14. MSE and Voice Nets

COMMANDERS TACTICAL TERMINAL/HYBRID

C-31. A commander's tactical terminal hybrid (CTT/H) is installed in the TCS and ICC. The CTT/H is a special purpose receiver that allows Patriot to receive intelligence information from various intelligence sources within theater. The CTT/H allows TIBS data to be displayed in the TCS and ICC for situational awareness and planning purposes.

PATRIOT COMMUNICATIONS PLANNING

C-32. Communications planning begins while the fire unit locations are selected to support the defense design. Enhancements with Configuration 3 and PDB-5 software have altered the technical capabilities of Patriot communications, but have not altered the basic method of conducting communications planning. There must be voice and data links created between each fire unit, ICC, CRG, and LCS location.

C-33. Patriot communications consist of AN/GRC-103 UHF, a joint tactical information distribution system (JTIDS) 2M terminal to the ICC, the integrated digital operator control station (IDOCS), RLRIUs, corner reflectors, LCSs, and AMGs. These items are used to execute the battalion's communications plan.

PLANNING RESPONSIBILITIES

C-34. The battalion signal officer, in conjunction with the S3, coordinates with brigade staff and adjacent signal officers to develop the communications plan prior to each move. A well-developed communications plan ensures you have communications at new positions.

C-35. The signal officer prepares the communications plan using the signal annex to the TSOP and the SOI. Frequency management personnel can assist in developing several areas of the plan. The following are steps the signal officer must consider as part of the planning process.

  • Review operations order from higher echelon, and evaluate the defined area of operations.

  • Conduct a ground or map reconnaissance to determine line-of-sight supportability. This analysis can be accomplished using the TCS communications planning function.

  • Request pre-approval for possible communications sites based on line-of-sight supportability and availability. These sites will be coordinated with the defense design when determining placement of Patriot units.

  • Prepare for publication of signal annex to OPORD—

    • Coordinate with JICO for battalion OPTASK links, and prepare data for tab entries.

    • Coordinate TADIL-J network, load files, and prepare data for tab entries.

    • Request frequency sets from higher for FM, AM, CTT, TADIL-A, TADIL-B, TADIL-J, ATDL-1, and PADIL networks.

    • Coordinate for connectivity to higher echelons, joint, and multinational forces.

    • Prepare network diagrams for voice, data, computer LANs, and multi-TADIL networks. Diagrams must include locations, frequencies, antenna azimuths, relays, and alignment.

    • Plan, develop, and organize communication support organization.

  • Prepare for publication of signal annex to OPORD.

  • Have at least one dedicated AN/PSC-5 tactical satellite (TACSAT) radio per battalion. SIGO must coordinate for TACSAT COMSEC for employment of TACSAT communications.

  • Coordinate for additional signal support with higher headquarters for satellite communications (SATCOM) when LOS and organic communications are not possible.

  • Request SOIs for battalion (distribute, maintain control and use of CRYPTO material).

  • Ensure there is logistic support for isolated sites (personnel, fuel and rations).

  • Monitor all communications links and prepare communication plans for contingency operations.

PRIMARY CONSIDERATIONS

C-36. When developing the communications plan, the signal officer must consider a number of factors. This list is not exhaustive and will vary depending on the situation.

  • Identify all network units interbattalion-total number of Patriot and THAAD FUs, CRGs, and the ICC), interbattalion (adjacent ICCs and subordinate German Hawk operations center), and extrabattalion (brigade TOC elements), and their UTM coordinates. The system can use up to six CRGs.

  • Evaluate site terrain for line-of-sight emplacement of antenna mast group (AMG) or corner reflectors. For planning purposes, 40-kilometers are the effective line-of-sight range for AMG in the bypass mode. The planning range for corner reflectors is 10-kilometers.

  • Plan for polarization of UHF antennas.

  • Define the patching scheme for each battalion element. Assign antenna azimuths for each link.

  • Assign battalion identification numbers to generate RLRIU addresses for local battalion elements. The RLRIU address defines the RLRIU that delivers the data block.

  • Identify the interbattalion or extrabattalion exit and entry port (ICC or CRGs 1 through 4) and shelter modem (1 through 5) to be used for each interbattalion or extrabattalion link. Direct linking, discussed later, offers an alternative to the use of modems for interbattalion communications.

PLANNING THE COMMUNICATIONS NETWORK

C-37. Communications network planning requires close coordination between the signal officer and the S3 section. The S3 informs the signal officer of proposed unit locations determined by the defense planning. The signal officer determines the need for CRGs based on the distance between units and the terrain. Once the UTM coordinates of the deployed units are known, the locations are plotted on a map to determine profile elevations and to verify distance between units. Technical data for this is provided in TM 11-5820-540-12. The same information displayed on the notational battalion UHF link diagram in Figure C-15 will be required in the standard five-battery configuration. Pictured below is a three-battery configuration with two CRGs. A five-battery configuration would have additional CRGs with all shot groups correlating with each other and then to the ICC. The diagram should contain the UTM coordinates and elevation data for each ECS, ICC, and CRG.

Figure C-15. Notational Battalion UHF System Diagram

Figure C-15. Notational Battalion UHF System Diagram

STANDARDIZATION

C-38. Standardization of communications tasks is essential for rapid system emplacement and operations. To the maximum extent possible, basic and communications functions should be standardized. Redundant links provide alternate paths for voice and data communications.

COMMUNICATIONS PATCHING PANEL

C-39. Standardization at the ICC is achieved by the way voice party lines and data channels are patched. Party line 1 is patched to channel 1; party line 2 is patched to channel 2 of whichever UHF radio is being used; party line 3 is patched to channel 3, and party line 4 with data is patched to channel 4. The integrated digital operator control station (IDOCS) modernizes the system communications for interconnection, access, and monitoring of VHF, HF, TADIL-A, voice, and tactical party line conferencing. The IDOCS provides a means for patching voice and or data via electronic patching using the new communications OCU touch panel screen, this includes the ground communications filter unit (GCFU) wire line circuits, UHF/VHF radio circuits and the switch multiplexer unit (SMU) circuit switching system. Data channels within the battalion will be patched from RLRIU port 1 to channel 1 of RRT 1, from RLRIU port 2 to channel 2 of RRT 2, and so forth. This process will continue until all patching is complete.

DATA CHANNELS

C-40. Channel 4 is dedicated for intrabattalion data transmissions. Channel 12 should not be used for data transmission since a synchronized pulse is routinely sampled from this channel. However, channel 12 can be used for voice transmissions. For more information concerning the use of communication, transmissions, and channels see FM 3-01.87. Through IDOCS, the user determines UHF radio traffic. A default setting on IDOCS allows direct access from the RLRIU, OCU voice battle circuits (2) and system management circuits. If the transmission rate over the UHF radio link is sufficient, the operator can allow the transmission of a FO-DTG containing 8 or 16 channels and a packet switch circuit. Figure C-16 provides the possible IDOCS/radio transmission rate and channel access available.

EO-Group/CH.

Rate (Kbps)

576/32

576/16

512/16

288/16

Service

Ch's

Kpbs

Ch's

Kpbs

Ch's

Kpbs

Ch's

Kpbs

PADIL Data

1

32

2

32

2

32

2

32

2 Battle Circuits

4

128

8

128

8

128

8

128

System Management

1

32

2

32

2

32

1

16

Overhead

1

32

1

16

1

16

1

16

FO-DTG

8

256

16

256

16

256

-

-

Packet Switch (16,32,64)

1,2

32,64

1,2,4

16,32,

64

1,2

16,32

-

-

Total Ckts/Bandwidth

16,17

512,544

30,31,33

480,496,528

30,31

480,496

12

192

Spare Channel Pool

2,1

64,32

6,5,3

96,80,

48

2,1

32,16

6

96

Figure C-16. IDOCS Channel Access Availability

BATTALION AND INTERBATTALION COMMUNICATIONS

C-41. The five modems at the ICC and CRG are used for communications with brigade and adjacent units. Standardization is achieved by assigning; for example, modem 5 to channel 5 of whichever RRT is being used by the ICC or the CRG. Direct linking provides an alternative to the use of modems for interbattalion data communications. This process increases data throughput and provides data flow between lateral ICCs when modem hardware is unavailable. Up to six direct links can be established during initialization. For example, at initialization, the special direct link source codes to be accepted from battalion B over a direct link are set in the battalion A RLRIU. All data packets originating in battalion B will flow over any direct link antenna path established between the two battalions. Only those data packets carrying the authorized data link source codes will be relayed into the battalion A net and passed into the battalion A computer by the ICC's RLRIU.

C-42. At battalion B, the same special direct link source codes are used in the RLRIU. Therefore, packets from battalion A carrying the authorized direct link source codes will also be relayed into the battalion B net and passed into the battalion B computer. A battalion net may also act as a relay between two other battalions using direct linking see Figure C-17 for illustration.

Figure C-17. Direct Linking

Figure C-17. Direct Linking

PARTY LINE LOOPS

C-43. The party line loop switches located on the front of the battery CP must remain in the NORM position at all FUs and in the OPEN position at the ICCs. CRGs are also a part of communications standardizing.

UHF Radio

C-44. Use the same AN/GRC 103 radio at both ends of the link: for example, RRT 1 at the ICC to RRT 1 at FU 1. By setting up links in this manner, troubleshooting the links using the communications fault data tab at the ICC is made easier.

PADIL NETWORK

C-45. In developing the data link network, the signal officer uses the ICC, CRG, and CRG/LCS deployment FU communications assignment to designate communications links, antenna azimuths, unit ID codes, and CRG locations. Up to six CRGs or LCSs may be deployed. A LCS is assigned the CRG symbol for display.

C-46. The FUs, the ICC, and the CRGs are shown in the communications diagram as a 360-degree perimeter. The distance from a unit to its perimeter represents 20—kilometers, which is half the nominal communications planning range. In determining whether units can communicate with each other, the individual observes the situation display and notes the proximity of the units to one another. If the symbols touch or overlap each other, they should be able to communicate without having to relay through a CRG. This assumes that the AMG is used and LOS exists. (If the unit symbols do not touch, the overall separation is 40—kilometers or more, and a CRG is required).

SYSTEM INITIALIZATION

C-47. Once a communications plan is developed, the communications personnel in the ICC, ECS, and CRG/LCS must implement it. Operators at the ICC, CRG, and ECS use the previously discussed system diagram and the communications planning work sheet as guides in their emplacement procedures. This is only for the remote launch and communications enhancement upgrade (RLCEU) units only.

C-48. Initialization of the voice patch panel is through the integrated digital operator control station (IDOCS) that provides an automated electronic patching facility. Through IDOCS, the user determines UHF radio traffic. A default setting on IDOCS allows direct access from the RLRIU, OCU voice battle circuits (2) and system management circuits. If the transmission rate over the UHF radio link is sufficient, the operator can allow the transmission of a force operation digital transmission group containing 8 or 16 channels and a packet switch circuit.

C-49. Initialization of the switch miltiplexer unit (SMU) will allow access to the ACUS network. Each Patriot shelter, ICC, ECS, and CRGs, can interface with the ACUS (MSE or TRI-TAC) supporting communications systems in the same fashion as used at the ICC.

C-50. Once the system is initialized, the operational software monitors and checks the RRTs, RLRIUs, and modems at all units (ECS, ICC, and CRG). This information is displayed at the ICC in the communications link fault data tab. The tab, when used with the battalion UHF communications link diagram, is an excellent tool in determining link and equipment status. The information in the tab becomes available when data communications are established between links (RLRIU to RLRIU).

DATA LINK CONSIDERATIONS

C-51. The Patriot data communications system is a multirouted net, which provides the ICC with multiple communications paths for data transmission. This multirouted net provides the Patriot system with low vulnerability to electronic countermeasures (ECMs), equipment outages, and a high data rate capability.

C-52.Patriot data communications is defined by or limited to the 32-kbps UHF multirouting network. Each linked unit, depending on its data protocol and initialized linkage, uses (loads) a portion of that total capacity. Based on the communications net plan, the unit percent loading will be under 100%. If the percent goes over a 100%, the tactical operator will be alerted on the K-7 display and actions must be taken to reduce the link load.

C-53. In the ICC, the PDB-5 software improvement, the network loading is automatically calculated and displayed for currently linked units. For planned deployments, this percentage, referred to as the deployed net loading percentage (DNLP) is also calculated and displayed in communications tabs.

C-54. Data communications can be accelerated between ICCs by initializing a "direct-link." A direct link (up to five are possible) bypasses modem hardware at ECSs and CRGs and allows full access to the 32-kbps net capacity.

C-55. Data modems located only at the ICC and CRGs, (five each per shelter), are required for data communications with ATDL-1, TADIL-J and TADIL-B units. An example of this is brigade TOC, THAAD, CRC, and auxiliary units. Figure C-18 illustrates the data link software capability.

Figure C-18. Data Link Software Capability

Figure C-18. Data Link Software Capability

TACTICAL CONSIDERATIONS

C-56. Patriot multichannel UHF communications are subject to degradation under combat conditions. The system or operator may use the following procedures to help reduce the amount of communication degradation.

SYSTEM LOADING REDUCTION MEASURES

C-57. Given DNLP > 100 percent, to maintain optimum system performance, the ICC will automatically degrade gradually its data communications to Patriot FUs first and then to or with CRG modem-ported Hawk fire units (if linked). The number of messages on the link(s) to FUs will be reduced and lower-priority messages for FUs will not be serviced as often. Note: Engagement and engagement-related commands are high-priority messages.

OPERATOR LOADING REDUCTION MEASURES

C-58. Given an overloaded net where the DNLP is > 100 percent, the ICC operator will be alerted and must take the following actions:

  • Disallow communications to one or more units, which reduces that unit's load by approximately one-half. Data still flows from the unit to the ICC.

  • Reduce or eliminate "direct-links" to or with subordinate or adjacent ICCs that reduce that link's load by approximately one-third or greater.

  • Transfer CRG modem-linked units to ICC modems that reduce that link's load to zero. Data still flows to and from the unit(s). The unit(s) must be relatively close to the ICC, if no CRG relay exists. LOS is required and data addressed to the ICC is not multirouted.

  • Eliminate a data link to a unit(s) at the ICC, which reduces that link's load to zero. Data is disallowed to and from the unit. FU to FU communications have no loading reduction effect since FUs share the ICC's multirouting net.

RECOMMENDATIONS

C-59. The following are some basic rules for UHF data communications. Additional information can be found in FM 44-01.87:

  • Do not "overload." Although loading beyond 100 percent is possible, it certainly is not advisable. An overloaded net will result both by design and fact in degraded data communications.

  • Plan link loading. With predicted "allowable" numbers and combinations of units, a link load-planning matrix should be consulted. Should one not be available, as a rough planning tool, use the following figures for prediction: each CRG modem-ported Hawk FU—5 percent; each Patriot FU—10 percent; each initialized external battalion unit linked through CRG modems—15 percent; and on "direct-link''—20 percent.

  • Maximize use of ICC modems. From a network-loading standpoint, maximum use should be made of ICC modems, especially by collocated (1 to 5 kilometers) units, Hawk FUs when CRG availability is limited, and "relatively close" ATDL-1 or TADIL-D units. Again, units linked via these modems do not load the network or in any way affect the network's loading capacity.

  • No use of "direct-link." Increases data throughout the ICCs, and minimal use should be made of "direct-linking" due to their exorbitant impact on the network loading capacity. If loading capacity is sufficient (few links exist), direct links may be considered.



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