Meteor Burst Communications: An Additional Means Of Long-Haul Communications AUTHOR Major John P. Jernovics Sr., USMC CSC 1990 SUBJECT AREA C4 EXECUTIVE SUMMARY TITLE: METEOR BURST COMMUNICATIONS: AN ADDITIONAL MEANS OF LONG-HAUL COMMUNICATIONS THESIS: Recognizing the limitations and vulnerabilities of exist- ing communication systems and the ever-increasing requirement for additional communication paths with an over-the-horizon (OTH) capability, the Marine Corps and other branches of the military have shown an interest in the resurgence of meteor burst communications (MBC) and its potential applications. ISSUE: With technological advances and the corresponding improve- ments in the range and lethality of weapon systems, the dimensions of the modern battlefield have significantly increased. This enlargement of the battlefield, in conjunction with the enemy's improved capabilities to exploit vulnerabilities of existing systems, is placing an additional burden on an already strained C3I system. The ramifications of these facts have a significant impact on the Marine Corps' amphibious doctrine. Technology will ultimately dictate that future amphibious operations must be conducted from an OTH posture to reduce the risk and insure a certain degree of success. However, such a posture will place a new and substantial demand on our current beyond-line-of-sight (BLOS) long-haul communications capability. The employment of an MBC system, with its unique ability to reflect and re-radiate very high frequency (VHF) radio waves from the ionization trails of meteors, could provide the MAGTF commander with an additional BLOS communication means during an amphibious assault as well as augment the communications network in a widly dispersed area of operation once ashore. CONCLUSION: Although an MBC system is not a panacea for all future communication problems and requirements, it does offer a communications medium that provides several advantages over conventional means. The system's inherent interception, detection, and anti-jamming characteristics, nuclear survivability, simplicity, and low cost make it an attractive additional path to augment existing circuits and enhance the MAGTF commander's C3I system. METEOR BURST COMMUNICATIONS: AN ADDITIONAL MEANS OF LONG-HAUL COMMUNICATIONS OUTLINE THESIS: Recognizing the limitations and vulnerabilities of exist- communication systems and the ever-increasing requirement for additional communication paths with an over-the-horizon (OTH) cap- ability, the Marine Corps and other branches of the military have shown an interest in the resurgence of meteor burst communications (MBC) and its potential applications. I. INTRODUCTION A. Importance of C3 B. Expansion of the battlefield II. VULNERABILITIES/LIMITATIONS OF CURRENT COMMUNICATION SYSTEMS A. Satellite systems B. Single/multichannel radio systems C. Wire/cable systems III. HISTORY OF METEOR BURST COMMUNICATIONS (MBC) A. History of MBC technology B. Existing MBC systems IV. MBC PHYSICS, PARAMETERS, AND GEOMETRY A. Meteor phenomenology B. Meteor trail physics V. MBC SYSTEMS A. System operation B. Basic system configurations C. MBC advantages and disadvantages D. Technological advances VI. POTENTIAL MILITARY APPLICATIONS OF MBC A. Other services B. Marine Corps METEOR BURST COMMUNICATIONS: AN ADDITIONAL MEANS OF LONG-HAUL COMMUNICATIONS History has shown that success in armed conflict can be attributed to the establishment of effective command and control of forces on the battlefield. The commander's ability to make rapid decisions and maneuver his forces at critical moments are dependent on available and attainable information. However, the "fog and friction" of war are real battlefield dynamics that create the uncertainty that will severely challenge the commander's abilities in the command and control of his forces. Uncertainty will always be a factor encountered in the command and control process on the battlefield, but the magnitude of that uncertainty can be directly influenced by the commander's ability to obtain and disseminate information and provide guidance to his subordinate commanders. His ability to communicate his desires to his units while receiving simultaneous appraisals of situations on the battlefield enhance his perceptions of the battle and ultimately his decision-making process. Therefore, to establish an effective command and control system, it is imperative that a communications system be integrated that facilitates two way information flow while ensuring that the proper information is received by the proper individual. In essence, the effectiveness of the command, control, and communications (C3) systems and the ability of each system to respond to a rapidly changing situation will determine the degree of success on the modern battlefield. As warfighting has progressively become more sophisticated, involving larger forces, encompassing greater areas, and containing many new and more lethal weapon systems, the communication systems supporting the command and control functions have undergone a similar evolution. Communication methods have evolved from the basic use of visual signals, such as fire and smoke, to the capability of rapidly establishing world-wide "real time" communications through accessing terrestrial and Earth orbiting communication platforms directly from the battlefield. However, the advances in technology are also proving to be a double edged sword for our communication systems. As the cap- abilities of these systems increase, so does the usage of the system as a result of the demand for more information. Technolog- ical advances have also aided our enemies in countering our communication systems by exploiting their vulnerabilities and inherent limitations. Finally, the significant improvements in the range and lethality of modern weapon systems has expanded the width and depth of the battlefield which further taxes our commun- ication systems. This increase in the size of the battlefield has the greatest impact on the Marine Corps during amphibious operations. Because of the range and lethality of the enemy's weapons to the amphibious ships, amphibious assaults in the future must be conducted from an over-the-horizon (OTH) posture which will stress an already constrained communication system. The importance of an effective communication system in the command and control of our forces has increased their requirement for timely and reliable communication-electronics support. All combat units now possess a capability to establish and maintain communication links with higher headquarters as well as with subordinate units through a wide variety of equipment and trans- mission means. However, these communications systems are rapidly becoming saturated because of increased demands for information while they are simultaneously being constrained by limitations of the frequency spectrum, increased distances, and are becoming increasingly vulnerable to technological enhancements of the enemy's Radio-Electronic Combat (REC) capability.1 In addition, the principle systems such as satellite, single and multichannel radio, and wire/cable each possess a host of vulnerabilities and limitations which could degrade the overall communication system. Satellite communication technology began in the late 1960's and provided the military with a new means of beyond-line-of-sight (BLOS) communications. These systems offered exceptionally high throughput (information transfer capacity) with superior circuit quality. Currently, the two systems that are available for use by the Marine Air Ground Task Force (MAGTF) are the Defense Satellite Communication System (DSCS) and the Fleet Satellite Communication System (FLTSAT). Satellite communication for a very long time was considered the panacea for all communication related problems. However, as this technology matured, the limitations and vulnerabilities of satellites were realized. Although many of the critical vulnerabilities of satellites are highly classified and beyond the scope of this paper, there are several areas that can be addressed. Space is not a sanctuary. Like any operation on land, sea, or air, satellites are subject to a variety of hostile anti-satellite measures which include co-orbital interceptors, direct energy weapons, and electronic warfare. It is important to note that a damaged satellite is not rapidly nor easily repaired. In addition, the cost of establishing a terrestrial communication station, the inherent cost of the satellite, and the cost of launching the satellite into orbit makes this type of communications system very cost intensive. Finally, the number of channels available are limited by the small number of satellites in orbit and the large number of subscribers attempting to gain access to these existing channels. Single and multichannel radio systems make up the prepon- derance of the communication assets available to the MAGTF. Only single channel high frequency (HF) radio systems provide a notable BLOS capability. Single channel very high frequency (VHF) radios and multichannel VHF and super high frequency (SHF) radio systems are limited to line-of-sight (LOS) propagation. The range of these various systems varies from 3 miles to over 80 miles. This range can be further increased by the use of repeaters/relays to achieve a BLOS capability. All of these systems are vulnerable to the enemy's electronic warfare measures, but the multichannel systems are at the greatest risk since they normally operate in the "constant keyed" mode or, in otherwords, are continuously transmitting. The HF systems are capable of world-wide communica- tions, but the circuit quality is inferior to satellite communica- tions and prone to considerable interference and disruption due to ionospheric storms. All of these radio systems operate in sections of the electromagnetic frequency spectrum which are highly congested world-wide. In addition, none of these systems matches the throughput capability or circuit quality of a satellite system. Tactical wire/cable communication systems enjoy relatively high circuit quality and when these lines are properly conditioned they can pass exceptionally high volumes of data. The major limitation of such systems is the distance that they can cover. As the distance increases, transmission signal strength decreases, while noise on the circuit increases and eventually will reach a level where the terminal equipment will find the circuit unusable. In addition, installation of a wire/cable system is manpower in- tensive and only suitable for relatively static positions. Although these systems are not emitters like the previously dis- cussed systems, they are still vulnerable to the intelligence gathering capability of the enemy and to deliberate physical destruction by the enemy or inadvertent damage by friendly forces. As advances in technology alter modern warfare, the demands for higher capacity and reliability of our communication systems continue to increase. Recognizing the limitations and vulnerabilities of existing communication systems and the ever- increasing requirement for additional communication paths with an OTH capability, the Marine Corps and other branches of the military have shown interest in the resurgence of meteor burst communication (MBC) and its potential applications. MBC, as the name implies, involves the reflection/re-radia- tion of radio signals from the ionization trails left by meteors entering the Earth's atmosphere. These reflected/re-radiated signals can be used effectively for long range communications and telemetry. MBC is a relatively mature technology. The earliest observation of interaction between meteors and radio communications was reported in 1929 by Hantaro Nagaoka of Japan. In 1931, Greenleaf Pickard reported that there was a definite cor- relation between increases in signal levels and meteor showers. He postulated that meteors increased ionization in the atmosphere which acted as a mirror-like reflector of radio waves.2 It was not until 1946, in research conducted by the Federal Communications Commission, that a direct correlation between enhancements in VHF radio signals could be linked to individual meteors. Studies conducted in the early 1950's by the National Bureau of Standards and the Stanford Research Institute had limited success, but confirmed that long-range VHF radio wave propagation could be attributed to meteor activity. A landmark to meteor burst communication was the establishment of the Canadian JANET system. Established in 1952 and operated throughout most of the decade, this system consisted of a full duplex circuit with a communication path in excess of 1000km which achieved a data rate of 34 words a minute.3 Subsequent experimental tests were conducted with second generation MBC systems in the 1960's and 1970's. Notable among these efforts is the implementation of COMET (COmmunication by MEteor Trails) system by NATO's Supreme Headquarters Allied Powers Europe (SHAPE) in 1965. This first operational military MBC system operated between stations in the Netherlands, France, Italy, West Germany, the United Kingdom, and Norway. COMET demonstrated the practicality of MBC under a variety of conditions. This system could maintain, depending on meteor act- ivity, from two to eight 60 word per minute (WPM) teletype circuits. COMET achieved an average throughput of between 115 and 310 bits per second, depending on the time of year.4 It became the most successful and studied MBC system installed until the late 1970's. Interest in MBC waned because of the advent of satellite com- munications in the late 1960's. However, in the late 1970's there was a resurgence of interest in MBC as the vulnerability of com- munication satellites became apparent and the availability of satellites to meet our needs was insufficient. In 1978, the Department of Agriculture started operation of the SNOTEL (Snow Pack Telemetry System) system under the management of the Soil Conservation Service. By far the largest MBC system in the United States, this system consists of two master stations and more than 500 remote stations dispersed in inaccessible terrain throughout 10 western states. These unmanned remote stations are solar powered and provide reports every 24 hours when polled, on snow pack, precipitation, and temperature. The entire polling process only requires 20 minutes to obtain data from all of the remote stations. SNOTEL fully demonstrates the large network performance capability of an MBC system.5 There are a number of MBC systems operating in Alaska. The two largest operational networks are the Alaskan Meteor Burst Communications System (AMBCS) and the USAF's Alaska Air Command MBC system. AMBCS became operational in 1977 and is used by five federal agencies. The Bureau of Land Management maintains contact with their remote survey teams. The National Weather Service uses the system to remain in contact with remote weather stations. The Soil Conservation Service obtains data similar to that obtained by SNOTEL. Stream and river gauging is recorded for the U.S.Geologi- cal Survey while the Corps of Engineers obtains environmental data from the system. The USAF system became operational in the mid 1980's and is used as a backup connection between the Regional Operations Control Center (ROCC) located at Elmendorf AFB and 13 Long Range Radar (LRR) sites located in remote regions throughout Alaska. The primary communications for these organizations is provided by a satellite system but, because part of the satellite footprint extends into the USSR, it is extremely vulnerable to jamming. The MBC system will function as a backup system and send radar tracks from the LRR to the ROCC.6 This system has demonstrated the capacity to send adequate amounts of data to be able to maintain a real time radar display. Both Alaskan MBC systems have shown that MBC systems can operate in an auroral environment.7 For decades it has been common knowledge that the Earth is under constant bombardment by meteors. Each day, approximately a hundred billion meteors enter the Earth's upper atmosphere at a height of 120km and at a velocities between 10 and 75 kilometers per second. The typical meteor that enters the atmosphere is about one millimeter in diameter or about the size of a grain of sand. Considering the large number of meteors entering the atmosphere, only a small number are actually usable for communications. Meteors with a mass greater than 10-7 grams are suitable to reflect radio waves.8 Although the number of these usable meteors is considerably less than the total number of meteors entering the Earth's atmosphere, they still number over several billion daily. The billions of meteors that enter the Earth's atmosphere on a daily basis do not enter at a uniform rate. Generally, meteors can be divided into two classes: shower meteors and sporadic meteors. Shower meteors are groups of particles moving at the same velocity in well-defined orbits around the sun. As the Earth passes through this orbit, they produce a spectacular show for the observer. However, shower meteors account for a small fraction of the total incidence of meteors. The other class of meteors are referred to as sporadic meteors. These consist of particles that move in random orbits around the sun and account for the majority of meteors used in long range radio wave propagation. Their location in the atmosphere and the times of their occurrence are random. However, the rate of incidence of sporadic meteors varies during the time of day as well as vary during the season. The optimum time of day for meteor communications is during dawn of each day, which has the highest incidence of meteors entering the atmosphere. The lowest incidence is during sunset. This diurnal variation occurs as a result of the morning side of the Earth sweeping up meteors as it moves forward in its orbit around the sun. Conversely, on the evening side, the only meteors reaching the Earth are those which overtake it. Seasonal variations occur because the intersections of meteor orbits with the Earth's orbit are not uniformly distributed, but are concentrated so as to produce a maximum of intersections in August and a minimum in February.9 Of the billions of meteors entering the atmosphere every day, only a small number are suitable for communications. One may ask, what is MBC and what are the actual physics involved? As already mentioned, it is the reflection/re-radiation of radio waves from a meteor, resulting in a telecommunications link. However, the communications signal is not reflected/re-radiated by the meteor itself but from the ionized trail it leaves as it travels through the atmosphere. As the meteor enters the Earth's atmosphere, it is traveling between 10 and 75 kilometers per second. At approximately 120km above the surface of the Earth, it encounters air molecules of sufficient density that friction builds up between the meteor and these air molecules. The heat that is pro- duced evaporates atoms from the meteor. These boiled off atoms collide with the surrounding air and produce additional heat, light, and ionization, which forms a meteor trail. This trail is essentially a column of ionized air, which acts like a conductor, and reflects and re-radiates radio wave energy. The ionized trail caused by a meteor can be classified as either overdense or underdense and is determined by the electron line density of the trail.10 Underdense trails have a low density and, when radio wave energy passes through these trails, individual electrons are excited and re-radiate the signal back to Earth. Overdense trails have an electron line density so great that radio signals can not penetrate the trail and are actually reflected back to Earth. The majority of meteors entering the atmosphere produce underdense trails. The length of the ionized trail is dependent on the mass of the meteor and the angle at which the meteor enters the atmosphere. Trails can reach up to 50 km in length but normally average 15km in length. In addition, the ionized trail's usefulness for an MBC link diminishes rapidly due to the expansion of the trail through diffusion and the effects of strong wind shear in this region of the atmosphere. Meteor trail durations range from less than a second to several seconds. The burning up of meteors creates ionized trails which then permit radio waves in the lower VHF spectrum (30-100MHZ) to be reflected or re-radiated from these trails for distances up to 2000km. To provide a communication channel between two stations, a meteor trail must be spatially located in the common volume of the antenna patterns of the two stations. Because of the short duration of the trails, information must be transmitted in a burst mode and messages must be kept terse. In addition, both transmit and receive station antennas must be illuminating the same region of the sky in order to establish a successful communi- cations link. This fact, and realizing that meteors enter the atmosphere in a random pattern, results in usable meteor trails every 4 to 20 seconds. An MBC link functions in the following manner. A probe, or polling signal, with the unique address of the specific remote where information is to be obtained, is sent repeatedly into the atmosphere from a master station. The remote station waits and listens for the probe with its specific address to be reflected by a meteor trail. This reflected signal returns to Earth in an elliptically shaped (10x35km) footprint. When the desired remote station falls within this footprint and is addressed by the probe signal, it sends back a message to the master station that the communication channel is open. The master station acknowledges the remote station and the "handshake" is complete. Communications between the two stations via the meteor trail can commence in a half or full duplex mode and continue until the trail dissipates and the channel closes. This entire sequence of events occurs in less than a second. The master station then returns to sending the probe signal to initiate the process. Because of the short duration of the meteor trail and the random nature of meteors entering the atmosphere, as much informa- tion as possible must be passed over the rapidly fading propaga- tion path. The majority of text messages transmitted over an MBC system are too long to be sent over a single trail. As a result, long text messages are divided into a number of smaller sections. Each of these sections is small enough to be transmitted over a single trail. These smaller sections are referred to as "packets".11 Each packet contains essential administrative information, such as bit sequence for synchronization, station identification, and error control. This information ensures correct reassembly of the original message and delivery to the proper addressee. When a long text message consisting of several packets is transmitted over an MBC system, the transmitting station will send as many packets of information as possible over an open channel. However, as the trail fades and the signal strength falls below a fixed threshold, the channel will close. The transmitting station will store any packets not transmitted until another meteor trail forms and is usable to transmit the remaining packets of information. The receiving station also places packets of information in que until all packets associated with a particular message have been received. Once all packets have been accounted for by the receiving station, they are reassembled into the logical sequence of the original message. At present, there are three basic equipment configurations for MBC systems. These are one station to one station, or point- to-point communications, one station to many remote stations, and interconnecting many stations, or complex networks. The simplest form of MBC station is a network composed of just two stations. This point-to-point configuration requires minimal consideration given to station addressing or coordination. A more complex sys- tem is the one station to many remote stations composition. This network connects a single master station to a large number of remotes and is ideally suited for an information gathering/teleme- try system such as AMBCS or SNOTEL. It can also be used as a "broadcast" mode communication system. The most complex MBC system involves interconnecting many stations. This config- uration is similar to the previous system except several sets of master and remote networks are interconnected. The increased system complexity compounds coordination problems and requires more detailed message formats and communication procedures.12 An MBC system operates by transmitting packets of digitized information when a meteor trail is usable for the reflection or re-radiation of radio waves. This form of communications provides numerous advantages over the more conventional types of systems, such as HF/VHF single channel radio, satellite and VHF/SHF LOS multichannel, and cable systems. An MBC system, used as a means of BLOS communications, ranging from 0-1200km, is less expensive to install and operate than existing systems because of its reduced requirements and costs associated with extensive ground station facilities, elaborate antenna systems, and expensive satellites. In addition, an MBC system is simple to operate, requiring minimal training and considerably less operator intervention than a typical HF circuit that requires an experienced individual to monitor it and make numerous frequency changes in order to maintain the circuit reliability. Meteor scatter propagation also provides an inherently low probability of intercept and detection (LPI/LPD) characteristics and anti-jam capabilities because of the burst mode of transmission, the small signal footprint, and random nature of the communication path.13 For an enemy to detect or jam such a system, he would have to be very close to either the transmitter or receiver. In essence, he would have to share the same geometry relative to the meteor trail as the MBC stations and fall within the relatively small signal footprint. This fact makes MBC systems more resistant to interception, detection, and jamming than conventional systems. Finally, an MBC system has significantly higher reliability than HF and satellite systems following a nuclear detonation. Following a nuclear explosion, the various layers of the ionosphere become highly absorptive to radio waves due to the vast increase in free electrons. Although MBC will initially be effected by a nuclear detonation, the recovery time will be considerably faster than that of the typical HF or satellite system. The D layer of the ionosphere where MBC radio wave propa- gation primarily occurs, recovers considerably faster than the E and F layers that HF propagation depend on and where satellite transmissions must traverse.14 Most literature indicates that an MBC network could be reestablished, albeit at a degraded level, in a few minutes following a nuclear event. MBC systems have several distinct disadvantages when compared to conventional BLOS communication systems. The greatest problem with MBC is its limited throughput when compared with existing long-haul systems. Currently, MBC is a low capacity system and is ill-suited to support the high capacity information demands of the modern battlefield. Current systems cannot support data rates in excess of a few hundred bits per second (BPS) nor support voice communications. Existing HF systems are capable of data rates of 1200 BPS while satellite systems can operate at speeds well in excess of 2400 BPS. By the very nature of the random meteor trails, MBC systems must wait until conditions are correct before transmission can occur. With available technology, although the waiting time for usable trails is only seconds or less, the wait requires buffering for data service and precludes normal voice communications. The traditional BLOS systems can provide real-time communications with a voice capability. An MBC system also operates most efficiently in a narrow range of frequencies in the lower VHF band. However, the spectrum in this band is extremely crowded with both military and commercial applications and obtaining frequencies that would not interfere with the weak signal strength of the reflected/re-radiated MBC signal would be difficult. Finally, the range that an MBC system could effective- ly cover has been a controversial issue. The maximum range of 2000km that MBC can cover has not been disputed. The minimum distance has been questioned. Some schools of thought contend that effective MBC can be achieved with 0km separation between stations while others contend that a minimum separation of approximately 400km is required between two stations to achieve the area of common sky necessary for meteor trail communications. The proponents of this theory attribute connectivity between stations closer than 400km as a result of LOS propagation. Regardless of whether communications occur as a result of meteor burst propagation or by traditional LOS means, MBC systems provide an inherent flexibility over existing communication means. The capability of providing connectivity in both LOS and BLOS ranges using the same VHF configuration has a significant advantage over other BLOS systems, such as HF. As already mentioned, MBC is a mature technology. The knowledge gained from the early years of research and observation of the early operational systems has resulted in a wealth of MBC data. This knowledge, combined with technological advances and innovations, is rapidly transforming MBC systems once characterized as slow and bulky. All major improvement trends have focused on the same goals of increasing throughput, decreasing the size of the equipment, improving the the LPI/LPD characteristics, and lowering production costs. Most recently, the integration of solid-state microelectronics into MBC systems has reduced their size and enhanced their capabilities. Advances in equipment with greater signal processing capability have dramatically increased the information throughput of MBC systems. The higher throughputs, considered with the inherent reliability/ survivability characteristics of meteor burst propagation as well as indications of even further potential improvements, indicate great potential for supporting tactical command, control, communications and intelligence (C3I) systems. The significant advances made in meteor burst technology in the past five years, with the probability of order-of-magnitude improvements in current performance levels in the very near future and the advantages that MBC has over conventional telecommunica- tion mediums, suggests robust tactical military application and potential strategic missions. The use of MBC systems by the military has been the subject of much study and specific applications were thoroughly reviewed by John D. Oetting.15 All of these studies have confirmed the utility of MBC as a means of supporting specific military requirements. However, these studies also identified the low throughput of MBC as a major limiting factor. Nevertheless, the general consensus continues to be that MBC is a viable communications media that can augment other exist- ing communication systems to insure continuous and reliable service in support of critical military requirements. The inherent flexibility, mobility, simplicity, jamming resistance, LPI/LPD characteristics, and nuclear survivability of MBC systems, combined with the BLOS long-haul communications cap- ability, enhances C3I at the theater and tactical force level. Although MBC is ill-suited to support high throughput requirements of existing high capacity systems, there are a number of low capacity, long-haul critical requirements that could be satisfied or augmented by an MBC system. Some examples of military appli- cations that would be suitable for an MBC system are: (a) Transmission of fire control instructions to remotely located weapon systems. (b) Transmission of fixed format messages between front line units and their higher headquarters. (c) Providing communications connectivity between a command element and a maneuvering unit BLOS. (d) Remote tracking of the positions of BLOS platforms such as ships, vehicles, and aircraft. (e) Providing telemetered data from remotely located sensor/ surveillance systems. (f) Providing communications connectivity between remotely located reconnaissance teams and higher headquarters. The military is actively involved with MBC systems. As already discussed, the Air Force has implemented an MBC system as a backup communication system connecting 13 remote radar sites in Alaska with the ROCC at Elmendorf AFB. The Air Force also manages the North American Aerospace Defense Command (NORAD) MBC network, consisting of three master stations and eighteen remote terminals, covering two thirds of the United States. This system is a backup for operational HF communications and its primary purpose is strategic reconstitution. The Navy has done considerable testing of MBC systems with particular emphasis on its applicability to tactical anti-submarine warfare (ASW). During FLEETEX 3-89 the Navy successfully tested an MBC system for tactical ASW connectivity and achieved 5 of 7 test objectives. Most notably, an MBC network with an 800 mile radius was established between Norfolk and Bermuda, which included 4 to 6 remote ships, and also resulted in successful integration of P-3 aircraft. The Army is also examining the feasibility of MBC applications for certain Special Forces operations. The dimensions of the modern battlefield have expanded sign- ificantly as a result of improvements in technology. The proliferation of numerous highly sophisticated and lethal weapon systems has necessitated dispersion of forces to insure survivi- ability on the battlefield. This expansion in the area of operation has increased the requirement for additional BLOS communication systems to assure adequate command and control of widely separated units. Future amphibious operations will further challenge existing long-haul communication systems and increase the requirement for additional BLOS means. The threat posed by enemy weapon systems will necessitate the amphibious task force to remain a considerable distance from the shore. This will theoretically place it out of range of the enemy's weapons and reduce the possibility of detection which will undoubtedly aid in tactical surprise. Continued advances in maritime technology will eventually enable the MAGTF to conduct amphibious assaults from a totally OTH posture. With this potential increase in the BLOS communication requirement, the Marine Corps is investigating the feasibility of utilizing MBC systems in various BLOS applica- tions to augment existing systems. The BLOS communication requirements for a MAGTF are already numerous and the growing need for an OTH amphibious assault capability will dramatically increase this already strained communications means. Since all ship-to-shore communications in such a scenario would be BLOS, an MBC system could be effectively employed on low volume data circuits. The additional capability offered by MBC could help satisfy the increased long-haul commun- ication requirements created by OTH amphibious operations. An MBC system could also be used to support potential contingency missions for a MAGTF that are to be conducted in the northern latitudes. The strategic importance of Norway to NATO's northern flank could result in a future site for a MAGTF deployment. Satellite and HF radio communication in these high latitudes have proven to be very difficult and unreliable on numerous exercises due to severe ionospheric conditions and the extremely low satellite-to-horizon angle, which is often obstructed by the mountainous terrain. Existing MBC systems operating at these higher latitudes have routinely demonstrated considerable success in BLOS communications. Because of the potentially large size of a MAGTF's area of operation, which could range in size from a few hundred to several thousand square kilometers, an MBC system installed at the command element (CE) could provide an effective inter-MAGTF network. The CE, which is normally located a considerable distance from the forward edge of the battle area (FEBA), would operate the master station while the ground combat element (GCE), the air combat element (ACE), the combat service support element (CSSE), and the amphibious task force would possess the remote stations. Such a system could pass short, formatted text messages to these remote subscribers. This MBC system could act as a backup path to a num- ber of different MAGTF communication circuits such as the Tactical, Command, Intelligence, or Communication Coordination radio nets. An MBC system could easily act as an overload circuit when any of the traditional BLOS communication links were saturated with high precedence message traffic. A number of the tactical applications of an MBC system capi- talize on the system's LPI/LPD and anti-jam characteristics, which make it especially suitable for operations deep inside enemy territory. Teams from Force Reconnaissance Company or Division Reconnaissance Battalion operate well forward of the FEBA and con- duct reconnaissance and surveillance on enemy activity. For these types of operations to be successful, considerable stealth and maneuverability are required. Manpackable MBC systems, with their inherent LPI/LPD characteristics, facilitate the covert nature of such operations and permit the transmittal of short messages at near real-time speed. An MBC system could also provide an additional BLOS communication means to the Light Armored Infantry Battalion (LAIB) in its reconnaissance or screening missions that could take elements of that unit over 100km forward of the FEBA.16 The reduced threat of enemy interception and detection insures the covert nature of these operations and also reduces their vulner- ability to the enemy's indirect weapons fire. Finally, an MBC system has considerable potential in the area of remote sensors. Currently, sensors in the Marine Corps' inventory have a nominal range of approximately 50 miles. Radio relay equipment must be employed to extend this range.17 However, the use of an MBC system to provide sensor telemetry data would not require the addition of a retransmission site to enhance its already long range. In addition, the anti-jam characteristic of these systems allows relatively reliable (error free) reporting from unmanned sensors of various types to fusion centers or other command/intelligence centers from distances equal to the maximum range of the MBC system. Based on this fact, sensors could be either hand emplaced or air dropped much deeper into enemy terri- tory and subsequently provide intelligence and earlier warning to the MAGTF on the potential enemy threat or capability. Recognizing the limitations of conventional communication systems, the threats against BLOS communications from enemy elec- tronic warfare capabilities, and the rapid saturation of current BLOS communication systems during amphibious operations, the Marine Corps has actively pursued the aquisition of an MBC system. The Marine Corps is developing the MAGTF Expeditionary Command Communications System (MECCS) to augment existing long-haul BLOS communication systems, such as the TSC-95 and TSC-15 HF systems, with a new and enhanced capability.18 The MECCS package will com- bine the capabilities of a regular HF system with a satellite system and also include an MBC capability. Four prototypes are scheduled to be built and tested during FY 1991. However, due to severe budget constraints, this program, like so many other defense programs, may slide into the outyears or be cancelled altogether. MBC is a communications medium that promises considerable advantages over conventional communications means. In such areas as LPI/LPD, anti-jamming characteristics, nuclear survivability, and resistance to atmospheric conditions, MBC as a BLOS communica- tion system has significant capabilities that could be exploited by the military. The system's inherent covertness, due to its LPI/LPD and its anti-jam nature, provides the military with a form of communications with significant advantages over conventional systems and also provides an additional means of BLOS communications, which would greatly assist future MAGTF commanders during the execution of an amphibious assault. Although an MBC system has many advantages, it is by no means a panecea for the constraints and limitations of existing systems. A viable MBC system would only provide a means for an alternate or additional long-haul channel of communications. Such a system would both supplement and compliment existing MAGTF communication systems and provide a means to fulfill the increased requirement for BLOS communications. An MBC system also has numerous disadvantages, with its limited throughput being the most critical. However, advances in technology, in conjunction with the inherent capabilities of MBC communications, provide for a new path for passing information between various subscribers with minimal concern for enemy interdiction. An MBC system will provide the commander with an additional means of augmenting his C3I systems which will ultimately help reduce the uncertainty of the battlefield. ENDNOTES 1 MCDEC, USMC, Electronic Warefare Operations Handbook, OH 3-4 (Quantico, 1979), pp. 27-41. 2 DCA, Meteor Burst Communications (MBC) Technology Assessment Draft, JTC3A Report 8213 (Fort Monmouth, 12 Dec 1988), pp. 2-14 - 2-15. 3 Bernal B. Allen, Meteor Burst Communications For The U.S. Marine Corps Expeditionary Force, Masters Thesis (Montery, 1989), pp. 1-3. 4 DCA, JTC3A Report 8213, pp. 2-16 - 2-17. 5 Manes Barton, "SNOTEL: Wave of the Present," Soil Conservation, (Mar 1977), pp. 8-12. 6 Phillip K. Heacock and Frank D. Price, "How the USAF Talks On a Star!" Popular Communications, (Sep 1984), pp. 44-47. 7 Edward J. Morgan, "The Resurgence of Meteor Burst," Signal, (Jan 1983), p. 70. 8 DCA, JTC3A Report 8213, pp. 2-1 - 2-3. 9 DCA, JTC3A Report 8213, pp. 2-3 - 2-12. 10 Allen, Masters Thesis 1989, p. 8. 11 Kenneth J. Kokjer and Thomas D. Roberts, "Networked Meteor-Burst Data Communications," IEEE Transactions on Communications, V. 24, (Nov 1986), pp. 25-27. 12 Allen, Masters Thesis 1989, pp. 31-34. 13 Allen, Masters Thesis 1989, p. 55. 14 DCA, JTC3A Report 8213, p. 4-3. 15 John D. Oetting, "An Analysis of Meteor Burst Communications for Military Applications," IEEE Transactions on Communications, V. 28, (Sep 1980), pp. 1599-1600. 16 William C. Boden, "LAV Logistical Support Forward of the FEBA," Marine Corps Gazette, (Feb 1988), p. 61. 17 Lynn W. Sabin, "Employment of Sensors," Marine Corps Gazette, (Feb 1989), p. 31. 18 MCRDAC, USMC, Horizons, (Quantico, Nov 1989), p. 17. BIBLIOGRAPHY Allen, Bernal B., Meteor Burst Communications For The U.S. Marine Corps Expeditionary Force, Masters Thesis, Naval Post Grad- uate School, Montery, CA. 1989. Barton, Manes. "SNOTEL: Wave of the Present," Soil Conservation, (March 1977), 8-12. Boden, William C., "LAV Logistical Support Forward of the FEBA," Marine Corps Gazette, (February 1988), 30-35. Browne, Malcolm W., "Radio System Uses Fiery Meteor Trails to Transmit Data," The New York Times, August 22, 1989, Section C., p. 1. Defense Communication Agency, JTC3A Report 8213, Meteor Burst Communications (MBC) Technology Assessment Draft, Fort Monmouth, 12 Dec 1988. Forsyth, P.A., Vogan E.L., Hansen D.R. and Hines C.O., "The Prin- ciples of JANET-A Meteor Burst Communications System," Pro- ceedings of the IRE, V. 45, (December 1957), 1642-1657. Heacock, P.K. and Price F.D., "How the USAF Talks on a Star!" Popular Communications, (September 1984), 44-49. International Telephone and Telegraph Corporation. Reference Data For Radio Engineers Sixth Edition, Indianapolis,IN: International Telephone and Telegraph Corporation, 1977. Kokjer, K.J. and Roberts T.D., "Networked Meteor Burst Data Communications, IEEE Transactions on Communications, V. 24, (November 1986), 23-29. Morgan, Edward J., "Meteor Burst Communications an Update," Signal, (March 1988), 55-61. Morgan, Edward J., "The Resurgence of Meteor Burst," Signal, (Jan- uary 1983), 69-70. Oetting, John D., "An Analysis of Meteor Burst Communications for Military Applications," IEEE Transactions on Communications, V. 28, (September 1980), 1591-1601. Sabin, Lynn W., "Employment of Sensors," Marine Corps Gazette, (February 1989), 30-35. Sugar, George R., "Radio Propagation by Reflection from Meteor Trails," Proceedings of IEEE, (February 1964), 116-135. U.S. Marine Corps. Marine Corps Combat Development Command. Communications, FMFM 3-30 Quantico, 1989. U.S. Marine Corps. Marine Corps Development and Education Command. Electronic Warfare Operations Handbook, OH 3-4 Quantico, 1979. U.S. Marine Corps. Marine Corps Research, Development, and Aquisition Command. Horizons, Quantico, November 1989. Weitzen, Jay A., "Communicating Via Meteor Burst at Short Ranges," IEEE Transactions on Communications, V. 35, (November 1987), 1217-1221.

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