On Sept. 11, 2001, terrorists turned American airliners into weapons of mass destruction. Within one month of the attacks, major U.S. carriers, already experiencing losses from a weak economy, reported declines of more than 30%. To curb the massive plight of American airline carriers, the government stepped in with a $15 billion emergency rescue package. Air security became the nation's top priority.

A part of that became a global call for new terrorist-fighting technologies and innovations, which came from the Technical Support Working Group (TSWG), a clearinghouse run by the U.S. Defense and State departments, last October. The organization set a Dec. 23 deadline for one-page concept proposals on anti-terror technologies. Then, on Nov. 19, President Bush signed an aviation security bill that he said should give Americans greater confidence when they fly.

This presents an enormous opportunity for tech companies, and the market has reflected it. Following the attacks, investors rallied around security and defense stocks, especially suppliers of military electronics, such as Raytheon, which reports a significant rise in its defense business.

Commercial airlines have begun to reveal which security technologies they plan to introduce in the coming months as a result of the increasing terrorist threat. To keep airliners from again becoming colossal fuel bombs, carriers are considering audio- and video-monitoring equipment, face recognition technologies, terrain warning equipment upgrades, and remote aircraft control, much of which includes one or more wireless interfaces.

Honeywell, Morris Township, NJ, has gone company-wide in designing new aviation security products and has launched an enhanced safety initiative to develop ways to use new and existing structural systems to increase security on the ground and in the air.

The company has appointed Frank Daly, air transport president, as its aviation safety leader and has committed to making near-term (over the next three to 12 months) security improvements that include a new airborne video-audio system to alert flight crew members to a situation; hardened cockpit doors using fiber products; cabin and flight deck systems to alert ground authorities of an emergency; an uninterruptible data-link to send flight data and cockpit audio to air traffic controllers in an emergency; tamper-proof Mode “S” transponders for all aircraft that would transmit aircraft identification, speed, differential GPS position and other information to ground authorities; and dual, combination flight data-cockpit voice recorders that would double the probability for recovery of investigative data.

Some companies are developing monitoring technologies that use satellite systems to broadcast live cockpit communications.

Honeywell began work last December with Iridium Satellite, Arlington, VA, to jointly develop a satellite communications link that will send continuous live cockpit audio from an aircraft in trouble to authorities on the ground. The voice and data signals captured by the recorders would also be transmitted to the Iridium constellation and sent directly to secure FAA data centers for live monitoring. The system is called Cockpit Audio Monitoring. The company plans to develop several versions of the technology to accommodate a variety of airlines and other users. These may be based on other satellite communications systems, airborne telephone systems, and very high frequency (VHF) aircraft communication radios.

Qualcomm, San Diego, has introduced a similar system called the MDDS that uses a global satellite constellation operated by Globalstar Telecommunications, San Jose, CA, to beam real-time cockpit conversations and live video streams to and from ground services. Through the Globalstar pipeline, Qualcomm's technology can support remote control of onboard aircraft cameras, transmission of real-time aircraft flight data to the ground; on-the-ground access to, and possible automated real-time monitoring of, flight data and cockpit voice recorders; and back-up transponders with aircraft identification, altitude, speed and location information.

Boeing also has a broadband satellite connection service, which was initially aimed at bringing Internet access and video to passengers in flight. The system, called Connexion, may now be modified to send images from aircraft to ground stations.

Such systems will be the cutting edge in protecting the communications infrastructure from terrors such as those that created the wake-up call of September 11. Audio and video monitoring of the cockpit may prevent such an act from happening again, while the black boxes that existed before could only help explain a crash after it was too late to stop it.

It is evident that the Federal Aviation Administration's (FAA) priority is not with secure communications so much as it is with airport security, and especially biometrics; however, the administration does have a committee reviewing communications proposals — none of which has been clearly identified for use.

“(The FAA) has not mentioned much in the way of communications because it is dealing with other threats involving passengers, crews, airport security and cockpit and cabin issues,” said spokesperson Tammy L. Jones.

While the FAA's priority may not be protecting communications, for the military it is a different picture.

From the early days of warfare, one of the major concerns of combatants is protecting information. While history books are filled with examples of how information is protected, the advent of airplanes changed how information was exchanged and protected.

During WWI, hand signals were a common way of communicating. One could say these were the ideal secure communications, however limited. But with the advent of wireless radios in military aircraft, the need to secure communications became a paramount concern. While a number of encryption devices and capabilities were developed, warriors found a way to decode the information. So, how do you protect classified communications?

While not directly developed for secure communications, frequency hopping became an important protection tool. The story behind its development (delivered by no less a figure than the 1930's movie star Hedy Lamarr) is intriguing. Developed to remotely guide torpedoes during WWII, the technology lay dormant until the Cuban missile crisis. Basically, frequency hopping takes a signal and modulates it with a carrier signal that does what the name implies — hops from frequency to frequency.

While this was a step in the right direction, today's requirements for secure communications are much more sophisticated.

The capabilities of today's secure aircraft communications are as varied as they are classified. While air-to-air communications are critical, it's air-to-ground, and ground-to-air secure communications that are most important to the air warrior.

It would be impossible to cover the many varied systems in use. (Not to mention that many of them are “black.”) However, a survey of the systems will give you some idea of what the military is using.

The most significant secure communications system in use by the military is SINCGARS, or Single Channel Ground and Airborne Radio. The first system in the SINCGARS family was the RT-1439/VRC. Developed by ITT Industries in 1987, the radio was a non-secure VHF frequency-hopping radio with a non-integrated communication security unit for secure communications (COMSEC). The technology behind the radio included 27 circuit boards using topside surface-mount devices and through-hole technology. It is worth noting that it contained no commercial parts. Process technology included leadless chip carriers, enriched resin PWB material, hairpin component forming and discrete wiring.

The system was upgraded with the ICOM RT-1702 (C)/U. This system used secure frequency hopping with data capability, enhanced display and an integrated COMSEC capability. With the increased capability, the number of boards required for the radio increased by only one to 28. Again, no commercial parts were used, but process technologies included dry film solder mask (tented VIAS) and solder columns (CCMD and S-lead).

The system was once again upgraded with the RT-1702 (C)/U. This upgrade offered increased battery life for ground systems and an enhanced message capability. The upgraded radio incorporated most of the technology from its predecessor, but with a decrease in board count to 24. A noteworthy 14% of the parts were commercial-off-the-shelf (COTS). Process technologies used in the radio included pin grid array (PGA), nickel/gold PWB surface finish and read-sided SMD components.

The next generation of SINCGARS was the RT-1702C(C)/U tactical communication system (TAS). This radio offered increased data throughput, packet data capability and a Global Positioning System (GPS) interface. The number of boards again decreased to 23 with 81% of the devices used in the radio COTS.

The current system is the advanced tactical communication system (ATCS), RT-1702E(C)/U. The system offers enhanced voice and data capability. In the migration of SINCGARS advancement, the radios used pure MIL-SPEC parts, and throughout their evolution, slowly adopted commercial parts. With the ATCS, 100% of all parts used in this secure radio are COTS. This represents a significant achievement and should quiet those who believe military systems require MIL-SPEC parts.

Realizing the need for compatible UHF communications capability, the U.S. Air Force and U.S. Army adopted the AN/ARC-164. The radio system was developed by Raytheon's Command, Control and Communication Systems to provide not only the DOD, but also NATO, with an anti-jam voice communications capability that is COMSEC-compatible.

The latest AN/ARC-164 radios feature military-standard, MIL-STD-1553B interfaces, ANVIS Green A front panel lighting and an electronic fill port. In addition, the ARC-164 features 10 W AM, 25 kHz channel spacing, line-of-sight-voice capability and a mean-time-between-failure (MTBF) of 2000 hours.

The system is used in a number of military aircraft, including the Air Force's F-15, F-16, E-8C Joint Surveillance Target Attack Radar System (JSTARS) aircraft and the F-117 stealth fighter. The system is also in use by Army aircraft such as the latest AH-64 Apache helicopter.

While the ARC-164 has been a mainstay in DOD and NATO secure communication systems, Raytheon has developed the AN/ARC-232(V) Starblazer airborne VHF/UHF multiband communications system, intended as a replacement for the ARC-164. The Starblazer was developed for use in fixed and rotary wing aircraft used for air defense and close air support. The design of the ARC-232 allows it to be a “form-and-fit” replacement for the ARC-164 and uses a MIL-STD-1553B data bus, RS-422 or ARINC 429 interface.

Technical features of the ARC-232 include an input voltage of +28 VDC to comply with MIL-STD-704D, power consumption of 150 W (transmit)/50 W (receive), frequency coverage of 30 to 400 MHZ, 8.33 kHz and 25 kHz channel spacing. The system can be upgraded to include an electronic counter countermeasures capability (ECCM) know as SATURN.

Last year, the Air Force awarded Harris a contract for a new tactical radio. The AN/PRC-117 multiband/multimission tactical radio is designed for use by Air Force tactical air control units. It allows them to communicate with tactical aircraft to request air-to-ground support. The Falcon II, as the system is known, offers embedded COMSEC, satellite communications (SATCOM) and ECCM capability.

One keyword in the military's communication systems (as it should be in the commercial world) is interoperability. The AN/PRC-117 is compatible with SINCGARS and other systems. To keep its interoperability, as waveforms change, the radio can be upgraded with a simple software change.

Technical features of the new radio include a VHF frequency range of 30 to 89.899 MHz (low) and 90 to 224.999 MHz (high); UHF frequency range of 225 to 512 MHz and UHF SATCOM frequency range of 243 to 270 and 292 to 31 MHz. The system offers 100 fixed and frequency-hopping presets and offers a number of voice modes. Voice modes include simplex or half-duplex, narrow-band, VHF low-band for SINCGARS ECCM and a narrowband cipher test digital voice capability.

It's no secret that much of the secure communications used by airborne systems depends on the use of military and, on occasion, commercial SATCOM. One of the primary satellite systems used by the DOD is the Milstar satellite communications system.

Milstar is a joint-service satellite communications system that provides secure, jam-resistant communications. The multi-satellite system can link not only aircraft, but also ships, submarines and ground vehicles, as well as ground stations.

Each of the Milstar satellites serves as a “smart” switchboard and can direct traffic from terminal to terminal anywhere on earth. Each satellite actually “owns” the signal and can link or crosslink with other Milstar satellites. Also, each Milstar terminal can provide encrypted voice, data, teletype or fax communications and is interoperable between the services.

While much of the technical data behind the system is classified, the Air Force does offer that the system is capable of medium-data-rate communications at 4.8 Kbps to 1.544 Mbps.

In addition to Milstar, the DoD and other government security agencies depend on civilian satellite systems. These include the Advanced Communications Technology Satellite (NASA), the Geostationary Operation Environmental Satellite (National Oceanic and Atmospheric Administration), International Telecommunications Satellite Organization (Intelsat), Landsat, Orcomm (Orbital Sciences Corporation and Teleglobe of Canada) and a number of others.

Do all of these offer secure communications? No. The DoD turns to encryption capability (for an overview of encryption technology see the October 2001 issue of RF Design. The article can also be found on our Web site at www.rfdesign.com, under “From the pages of RF Design”)

While the military secures its communications, the FAA's primary concern, as previously mentioned, is with the physical security. To assume that commercial aircraft communications is not an asset that needs to be protected is misguided at best. From providing false information over a “hijacked” frequency to jamming communications, the threat is real.

But how easy is it? One needs only to go to the Internet to find Web sites offering surplus military radios and Web sites that offer the specific frequencies used by commercial and military airports and bases.

From thermal-imaging to EMMC, protecting aircraft depends on high-tech. If there are unsung heroes in this effort, it may well be the design engineers creating the next-generation technology that will better ensure aircraft security.

RSS    Save to Del.icio.us  Digg This