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Enhanced Position Location and Reporting System (EPLRS)

The first generation Enhanced Position Location and reporting System (EPLRS) was initially fielded to the US Army in 1996. At that time EPLRS was centrally managed via a large Network Control Station and offered 56kbps of user throughput through a military implementation of the X25 interface standard. Since 1996 EPLRS has undergone significant technology refresh. Today's 4th generation EPLRS no longer relies on centralized network management and provides 2Mbps of user throughput through an industry standard TCP/IP interface. All of the (27,000+) EPLRS radios fielded to data have already been or shortly will be upgraded to the latest capability.

EPLRS is a mobile ad-hoc network (MANET) providing jam-resistant data communications over the modern battle space. Utilizing Direct Sequence Spread Spectrum, Time Division Multiple Access, Frequency Hopping and Forward Error Correction technologies, EPLRS provides the means for high speed information distribution. The network provides automatic and dynamic relaying for networking in complex terrain and beyond line-of-sight coverage. Additionally, EPLRS provides GPS-independent position determination and dissemination for blue force tracking in GPSdenied environments. EPLRS is employed by all four branches of the US Armed Forces as well as allied nations. EPLRS has undergone continuous evolution since first being deployed in 1996. Today's 4th Generation network provides 2Mbps of user throughput via a fully automatic MANET. No pre-planning or active network management is required. Radios are available in two variants; vehicular and man wearable. The optional network manager runs on a Toughbook personal computer.

System Characteristics:
TAMCN: A2152
NSN: 5820-01-502-4040
Technology: Digital
Spectrum: UHF
420- 450 MHz frequency hopping
Orientation: Omni-directional
Mobility: OTM
Power: Vehicular 4 Settings; 100, 20, 3, .4 watts. Man-pack RT; 16 watts
Distance: LOS 6 miles, ground to ground per hop, max of six hops approximately 200 miles ground to air
Operational Mode: Data
Encryption: Terminal Electronics Unit Transec Module
Quantity Fielded: 1375 Radios
AAO: 3284

System Description:  EPLRS currently consists of an ENM and radios that can be configured for man-pack or various ground platforms use. The AN/VSQ-2D(V)1 is a Data Net Radio that provides secure, jam-resistant radio frequency connectivity and positional location capabilities to the user.

The main components of the Radio Set are a RT (RT-1720_(C)/G), an EDPA, a URO device for entering and receiving messages, and the appropriate installation kit for the platform from which it is to be operated. The ENM is a ruggedized laptop-based software program used to establish, monitor and maintain the EPLRS network.

The ENM replaces the Enhanced Downsized Net Control Station that was initially fielded with the EPLRS. The ENM offers increased capability and significantly reduces the system footprint, taking the network management functionality from a HMMWV mounted system to a laptop.
GCE: HQ Bn, Comm Co, Inf Regt, ELMACO, Inf Bn, Arty Regt., Arty Bn., AAV Bn, LAR Bn. Cmbt. Eng Bn
CSSE: Comm Co

Programmatic Information:
Manufacturer: Raytheon
Contract Vehicle: Firm-fixed Price, USA Prime
MCSC Acquisition Status: 45% Fielded
IOC: 06/01/00
FOC: 09/30/04
Fielding Plan: Vertical
Unfunded Requirement: Yes

Lifecycle Configuration Control:
Initial Fielding: FY00
Quantity Fielded: 1375 Radios, 120
Warrenty: None
Logistics Support Concept: 2 Level (O-D)
Upgrades: Version 11.4
Legacy Equipment Substitute: PLRS
Lifecycle Status: Stable
Expected Replacement System: JTRS
Expected Replacement Timeframe: FY12-14
Stated Need:  Derived from the ROC for the EPLRS PIP dated 11 January 1991.
Operational Requirements Documentation (ORD):  U.S. Army ORD for EPLRS dated 28 November 1995, Reference #08027.
Concept of Employment:  EPLRS provides a dedicated, secure, and mobile data communications network for MAGTF C4I users. It will provide the data backbone for several Tactical Data Systems and connects the systems into a seamless and integrated exchange. EPLRS also provides automated friendly Position Location Information and navigation information via GPS based-systems. EPLRS enables data exchange in unicast and multicast modes and is compatible with virtually all standard terminal device (DACT, TCO, TDN server, and AFATDS) via standard internet protocol. Within the Army and Marine Corps EPLRS is the digital backbone for the ground forces that are linked via the Lower Tactical Internet. The Navy's primary use of EPLRS is to provide over-the-horizon location and tracking of amphibious assault and logistics craft in support of Marine operations.
Operational Impact:  Provides mobile, secure LOS data communications between Regt and Bn forces, forming the data backbone for many tactical data systems. Version significantly enhances the capabilities of the system providing increased data rate from 57kbs to 486kbs as well as compatibility with CONDOR.
Cost: Low - Price and contract stable. End item developed and in production.
Schedule: Low - Army contract on schedule. FMF fully fielded. Reserve fielding incomplete, anticipate completion with upgrades. Upgrades on schedule.
Performance: Low - End item developed. Upgrades stable.

Status:  Version

First Generation Enhanced Position Location and Reporting System (EPLRS)

The first generation Enhanced Position Location and reporting System (EPLRS) was initially fielded to the US Army in 1996. EPLRS managed all the efforts for the EPLRS, SINCGARS, Frequency Hopping Multiplexer (FH MUX), Internet Controller (INC), MIDS, and the NTDR to ensure they meet their stated military characteristics, military requirements and program objectives. Has the formal authority of the Army Acquisition Executive in the responsibility and accountability to direct and control all for establishing program strategy and objectives on matters pertaining to cost, schedule, & performance of the stated programs.

EPLRS provides the Army with the ability to enhance Command, Control, and Communications (C3) capabilities by supporting Battle Functional Area (BFA) Engagement Operations (EO) and Tactical Internet (TI) requirements for battlefield data distribution, position location, navigation, reporting and friendly identification. SINCGARS is defined as those FM voice radios and associated ancillary equipment whose primary uses are for command and control of combat, combat support, and combat service support in the U. S. Army. MIDS is DOD's primary tactical data link for joint and international interoperability and situation awareness for Command and Control and Intelligence (C2I), commonly referred to as Link-16. CSEL is defined as the Combat Survivor Evader Locator program and is a multi-service program with the Air Force as the lead service. The CSEL system provides joint service and/or combined operational recovery forces with the capability to pinpoint the location and establish communications with downed aircrew members or other isolated personnel in need of extraction from hostile territories. NTDR provides the Army's Tactical Internet Tactical Operation Center (TOC) to Tactical Operation Center (TOC) data distribution from Battalion to Brigade and for all mobile TOC platforms from below Division in the First Digitized Division.

Previous Information




 PE & LINE #: 63713.D370 BU1400

 DESCRIPTION: The Enhanced Position Locating Reporting System (EPLRS) provides secure, jam-resistant, near real-time data communications support for the five Battlefield Functional Areas of the Army Tactical Command and Control System (ATCCS). EPLRS system was fielded in 1987. Because of the real-time unit positioning data supplied by PLRS/EPLRS, accurate battle management is now possible. This allows the battle commander to not only move forces forward, but to also quickly and accurately counter opposition moves.

The original version consisted of 1 UYK-7 and 3 UYK-20 computers. Later improvements, designed to enhance system level diagnostic procedures, substituted 3 Baseline AN/UYK-44(V) computers, with their high confidence Built-In-Test (BIT) capabilities, for the UYK-20s. The UYK-44s also allowed for expanded message functionality in the system as well as use of a 1553B interface, further enhancing overall system capabilities.

Unisys has been working on tasking from the USMC and the U.S. Army since 1991 to downsize EPLRS to fit into a smaller and lighter Standard Integrated Command Post System (SICPS) shelter on a HMMWV. To accomplish this, the 3 Baseline UYK-44s and UYK-7 computers are being replaced by a single, powerful, AN/UYK-44(V) Enhanced Processor (EP) MRC. This "Downsized" Net Control Station (NCS), shown in figure 3, is an integral part of the overall PLRS/EPLRS program, providing near real-time position and identification information on tactical forces as well as cryptographic message and data communications. The Real-Time Enhanced PLRS (RTEP) software resident in the UYK-44 EP and a AN/UYK-101 computer (a Miltope CHS-1 acting primarily as an operator interface) provides each NCS with expanded operations designed to support up to 460 active radio sets and, in a multiple NCS environment, each NCS can communicate with adjacent NCSs. The Downsized system's modular design, allowing LRUs to be easily removed and replaced, together with the Built-in-Test capabilities of the UYK-44 EP allow most maintenance tasks to be accomplished without special test equipment and using only standard tools.

EPLRS is a Time Division Multiple Access System using a frequency hopping, spread spectrum waveform in the UHF band. It incorporates internal COMSEC devices of the Thorton family and has an Over The Air Rekeying (OTAR) capability. EPLRS uses both the Army Data Distribution System version of the X.25 CCITT and MILSTD-1553B protocols to interface with ATCCS and selected weapons, and command and control systems. Additionally, EPLRS provides battlefield situational awareness to both the user and to their higher headquarters. This information greatly enhances the command and control of tactical units by providing commanders with the location of friendly units, a dynamic representation of the Forward Line of Troops and abbreviated SITREPs for conditions and identification of adjacent equipped units. The major components of EPLRS are the downsized Net Control Station-EPLRS (NCS-(D)), EPLRS Radio Set with its user input/output devices, and the EPLRS Grid Reference Unit (EGRU). A typical army division will have four NCS-E(D)s. 600-700 EPLRS Radio Sets, and 12 EGRUs. EPLRS deploys as a total system with NCS-Es controlling communities of EPLRS radio sets. EGRUs help with position location function and relaying of messages. EPLRS Radio Sets originate, relay and receive messages.

TRANSPORTATION CHARACTERISTICS/LIMITATIONS: NCS-E (D) 8.5'x7'x6', 4000lbs. EPLRS Radio Set 14.7"x10.5"x 5.1", 28lbs.

HISTORICAL BACKGROUND: EPLRS concept is a Preplanned Product Improvement (P3I) to the USA/USMC PLRS program. Technology insertions will be incorporated as part of the P3I process.

Sep 78 System definition contract award to HAC.

Jan 90 P3I Phase C (LRIP) contract awarded to HAC.

Jul 90 LRIP Option 1 awarded to provide test hardware for TT/OT.

Jan 92 LRIP Option 2 awarded for corps level ATCCS testing.

May 93 LRIP Option 3 awarded for corps level ATCCS testing.

Aug 94 IOTE at Fort Hood, TX.

May 94 VHSIC Contract awarded for production for VHSIC SMP's.

Jan 95 Initial fielding to 1st Cav.

Jun 95 Initial fielding to 24 ID (3ID).

Feb 96 Complete fielding (Phase II) to 1st CAV.

REQUIREMENT DOCUMENTS: PLRS/JTIDS Hybrid (EPLRS and JTIDS) Letter of Agreement approved Jun 82; ORD approved Nov 95; O&O revised Oct 86.









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Field 4ID (TF XXI)


Operational Test and Evaluation - Phase I


OT - Phase II


MIII Decision


Full Rate Production Award


EPLRS Downsize NCS


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