Smart minefield sought for anti-armor defense: network of weapons, sensors could help tactical commanders secure battlefield.

The Army is soliciting bids from contractors for a high-tech grid of weapons, sensors and command stations that would enable soldiers to lay clusters of anti-tank munitions in the forward areas of the battlefield, leave them unattended and control them remotely from the rear.

This is the basic idea behind a program called Raptor, an "intelligent" combat outpost consisting of a suite of munitions, sensors, a communication system and a control station. The munition for Raptor would be an upgraded version of the Hornet, also known as the wide-area munition. Hornet is a smart weapon that detects, classifies, tracks and engages ground armored vehicles.

In the future, the system could be adapted to accommodate other anti-rank munitions, nonlethal weapons or demolition obstacles, said Lt. Col. James Childress, division chief at the Army's program office for mines, countermine and demolitions, at Picatinny Arsenal, N.J.

Several functions are envisioned for Raptor--to guard flanks or screen a unit's front, as an outpost or a listening post for combat intelligence gathering, as a forward observer, cueing and directing fires.

The munitions would be hand emplaced--about 50 kilometers forward of the brigade's tactical operations center. Subsequent upgrades of Raptor will provide for other forms of delivery, via artillery or aircraft, Childress said in an interview.

The requirement for Raptor originated at the Army's Engineer School, about a decade ago. Combat engineers were interested in an intelligent minefield that could be controlled by the brigade commander at the tactical operations center.

But Raptor is more than just a minefield that can be remotely controlled, Childress explained. The system would have command-and-control nodes programmed with a set of instructions, based on what the sensors report. The munitions would be programmed to execute instructions autonomously, based on what the sensor perceives, or to take orders from the operator. If any nodes are destroyed or disabled, the network triggers a "self-healing" mechanism.

The Army issued a draft solicitation for Raptor last year and hosted an "industry day" in December 2001. Doreen Chaplin, project officer for Raptor, said that the Army will award two contracts in late 2002 for initial concept designs and component development. That phase will last about 30 months, at the end of which one contractor will be selected to continue the development work. If the program is successful, Raptor could become operational in 2010, she said. Contractor proposals for the first phase are due in July. Chaplin said that the solicitation does nor specify what type of hardware contractors should use--it only asks for "functionality." The Hornet munition is treated as "government-furnished equipment."

For the Raptor concept to come to fruition, meanwhile, the Army needs to successfully develop a new version of the Hornet, called Advanced Hornet. The current variant, or the basic Hornet, would be useless in the Raptor network, because it only has one-way communications, Childress explained.

At the core of the Advanced Hornet is a two-way communications and networking system, said Jay Johnson, director of Army programs at Textron Systems, in Wilmington, Mass. The company finished production of the basic Hornet and now is working on the development of the advanced version.

The basic Hornet only has a one-way radio, so a soldier can instruct it to turn on or to self-destruct. But the soldier never really knows whether the munition ever got the signal, Johnson explained.

A two-way communications system would allow the soldier to not only send instruction signals to the munition, but also to verify that the munition is doing what it was directed to do. The Hornet can engage targets from a standoff range of about 100 meters. Typically, early-entry forces would field Hornet to protect the flanks at the end of the line.

The Hornet's main body is a 35-pound cylinder (8-inches in diameter, 13-inches tall). It deploys legs to maintain stability on the ground. It comes with three kinds of sensors. Acoustic devices listen for vehicle sounds. The base has a seismic sensor, which feels the vibration of a vehicle. The basic Hornet has a single infrared sensor in the submunition that looks for engine heat. In the Advanced Hornet, there are two sensors in the submunition: infrared and laser-radar, which tracks elevations. When it locates the target, the submunition fires an explosively formed penetrator.

If the program proceeds as planned, the Army will start buying the Advanced Hornet in 2004. Its warhead would be the same copper submunitions used by the Air Force in the so-called Sensor Fuzed Weapon. "That saves the Army a lot of money," said Johnson.

The networking module and the secure data link in the Advanced Hornet were developed by Harris RF Communications, in Rochester, N.Y.

The company is about half way through the development cycle for the networking module, which uses the same technology found in Harris' VHF handheld radios, said Andy Adams, director of product management.

The challenge, he said, was to make a unit small enough that it would fit into a sensor or a munition and operate off a small battery. The company also developed wireless tactical networking protocols to help manage the bandwidth in the system. "Key to wireless communications is channel access," Adams said. "When you have a bunch of munitions trying to access the same channel, the key is to figure our who can talk when. Our technology centers around doing that efficiently, so we can pass around more data."

RELATED ARTICLE: Navy Mine hunting system gets long-range data link.

Tactical radios originally designed for land forces will help connect Navy warships with a new mine-hunting system. Even though the mine-hunter vehicle is submerged, its snorkel mast remains above water, making it a suitable platform for the radio's antennae.

Having real-time communications and data links are basic requirements in the remote mine-hunting system (RMS), said Brad Hines, program director at Lockheed Martin Naval Electronics and Surveillance Systems. The company is under contract to build two RMS prototypes, to be delivered to the U.S. Navy in 2003. The RMS missions are to detect, classify locate and identify bottom and moored mines in shallow and deep waters.

If the program is successful, the Navy will begin installing the RMS in new Arleigh Burke-class destroyers, beginning in 2005. These ships will have a dedicated RMS launch and recovery system. The RMS consists of a 23-foot-long unmanned, semi-submersible mine-hunting vehicle that tows a so-called variable-depth sensor, equipped with a variety of sonar, electro-optical and navigation sensors.

Hines said it makes sense for the Navy to adapt existing radios for the RMS, instead of developing a system from scratch. "I think it's logical to take equipment that's been proven in the military, do slight modifications and come up with something brand new," he said. "It saves money."

The data link for the RMS will be integrated into the ship's radio room. It will have both a line-of-sight and an over-the-horizon capability. The controller's status information for the RMS vehicle and the variable depth sonar is transmitted over these radios, as well as the data collected by the obstacle avoidance cameras and the sonar sensors.

The line-of-sight radio, with a range of 12-15 nautical miles, is a high-data rate system (3.15 megabits per second) that controls the status of both the RMS vehicle and the towed sensor. The radio is an ultra-high frequency AN/VRC-99B, made by BAE Systems. It operates in the 1.7-2.0 GHz frequency spectrum.

The over-the-horizon radio is a very high frequency (VHF) AN/PRC-1 17F, made by Harris RE Communications. Operating in a lower frequency (30-40 MHz), the 1 17F can transmit data at 45 kilobits per second. Its precise range is classified. "We are talking about tens of miles," said Hines.

A high-power amplifier enables the VHF signal to perform "surface wave propagation," in order to extend the line of sight beyond the horizon, said Hines. VHF radios typically only operate within the line of sight.

The signal propagation is caused by a "ducting effect along the water," said Joseph Stemowski, director of government programs at Hams. He explained that the radio wave is bent along the surface of the water to reach beyond the line of sight.

Even though the 117F is a land-based tactical radio, it suits the needs of the RMS system, because the antenna is above water, mounted on the vehicle's snorkel mast. If the system were completely submerged, it would not work. Harris engineers modified the radio slightly, in order to make it operate with the high-power amplifier, which was specially designed for the RMS.