Patent Application
20080122617
This invention is directed to a secure, above-ground high-speed data transmission cable, and particularly to a cable having a data transmission line and additional surrounding fiber optic lines for security monitoring which may be routed above ground.
Data transmission cables are routinely used to transmit highly sensitive data from one computer to another. For example, within a military facility, multiple computers may be linked together over data transmission cables. The users of these computers transmit highly sensitive data relating to military operations and national security over these cables. There exists a need to monitor the cables so as to avoid any interception and theft of the highly sensitive data transmitted on them. For this reason, the cables used in these military facilities are often limited as to their length, as they cannot be monitored over vast lengths.
It is of particular importance to monitor any cables that are above-ground as they are easier to access than buried cables. For a variety of reasons, it is advantageous in certain situations to have data transmission cables above-ground rather than buried. These cables must be monitored to ensure that the data being transmitted over them is not being intercepted by another party. Attempts have been made to monitor fiber optic cables in the past. These attempts have been limited to determining if the cable has been damaged.
U.S. Patent Application Publication 2004/0146254 discloses the insertion of an indicator that can be visually seen when the cable has been degraded. While this allows for repair of a damaged cable, it does nothing for securing the underlying fiber optic data transmission cable and data.
Other attempts have been directed toward cables that are buried under water. These cables must be monitored for damage internally as viewing a cable buried under the ocean is extremely difficult. For example, U.S. Pat. No. 4,623,218 discloses the use of electrical leads within the cables that complete a circuit to send a signal indicating that the electrical leads have not been damaged. Once the electrical leads that surround the fiber optic data transmission cable are damaged, the circuit that they complete is broken, and this indicates to an observer that damage has occurred to the cable. This allows cables that have already been damaged to be repaired.
Accordingly, an object of the present invention is to provide a secure high-speed data transmission cable protected against compromising of the cable and accessing of the transmitted data.
The above objectives are accomplished by providing a secure data transmission cable for electronically transmitting secure data between remote locations in an exposed condition. The data transmission cable comprises a tubular outer protective layer and an inner core disposed within the outer protective layer. A data transmission line is carried within the inner core for transmitting secure data between the remote locations. A fiber optic sensor line is included in the outer protective layer for detecting unauthorized activity relative to the transmission line.
The fiber optic data transmission line may comprise a plurality of optical fibers for transmitting data between remote locations. A protective casing surrounds the data transmission line for protecting the fiber optic data transmission line from contacting the outer protective layer. The casing includes an inner and an outer casing which move relative to each other to provide flexibility to the inner core. The sensor line may be carried within a hollow tubular strand in the outer protective layer which includes a plurality of reinforcing strands formed with the tubular strand to provide flexibility to the inner core. The tubular strands, which contain sensor lines, and the reinforcing strands may be metallic. A plurality of the tubular strands may be braided in the outer tubular braid wherein each of the tubular strands contains a fiber optic sensor line for detecting unauthorized activity relative to the transmission line.
The objectives are further accomplished by a secure data transmission system for securely transmitting data among remote computers connected by above-ground cables. A data transmission cable is provided for connecting first and second computers. The data transmission cable includes a data transmission line for transmitting data and a fiber optic sensor line for detecting unauthorized activity relative to the cable. A scanning unit is in communication with the fiber optic sensor line for continuously pulsing the sensor line to determine the status of the sensor line. A security computer is provided in communication with the scanning device for determining an initial baseline signal based on the initial pulse. The security computer then compares the baseline signal with a status signal determined based on a later pulse of the sensor line. A fault signal is generated in response to a predetermined charge in the status signal. An audible alarm is included for receiving the fault signal and audibly indicating the occurrence of unauthorized activity is connected to the data transmission cable. The scanning unit may comprise an optical time domain reflectometer (OTDR) for continuously pulsing the sensor line to determine the status of the sensor line.
The objectives are further accomplished by a computerized method for the high-speed, secure transmission of data along an accessible transmission line comprises transmitting data along a data transmission line. A protective layer of the cable is provided which surrounds the data transmission line having a fiber optic sensor line extending longitudinally through the protective layer. The sensor line is scanned to determine the status of the line. If a change in a signal transmitted along the sensor line in response to a prescribed attempt to compromise the transmission line is detected, an alarm signal is generated and transmitted to an associated alarm. The alarm is then actuated in response to the attempt to compromise the transmission line.
The construction designed to carry out the invention will hereinafter be described, together with other features thereof. The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown and wherein:
Referring now to the drawings, an illustrative embodiment of the invention will be described in more detail.
As can best be seen in
Data transmission line 14 includes a bundle of optical fibers for providing high-speed data transmission. Fiber optic data transmission line 14 is enclosed in an inner casing 17 and an outer casing 19 to protect the bundle of fibers from exposure that could compromise the data being transmitted. Protective casing includes inner casing 17 and outer casing 19 which are used to reinforce the strength of the inner core while allowing for bending of the cable without a loss of strength.
Preferably, there are three sensor lines, fiber optic sensor lines 16a, 16b and 16c, included in outer protective layer 10. The security lines may be braided around data transmission line 14 along with braided wires 15 to continuously protect fiber optic data transmission line 12 from unauthorized access along the length of the cable. The fiber optic sensor lines are adapted to carry signals that are used to determine the status of the sensor line. Note that in alternative embodiments, a single fiber optic sensor line may be used to protect a fiber optic data transmission line. In further embodiments, any number of fiber optic sensor lines may be included to protect data transmission line 14. The fiber optic sensor lines are enclosed in single cable jackets 18a, 18b, and 18c, respectively, to ensure exact measurements of the status of the sensor lines.
The detailed description that follows may be presented in terms of steps of methods or in program procedures executed on a computer or network of computers. These procedural descriptions are representations used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. These steps require physical manipulations of physical quantities such as electrical or optical signals capable of being stored, transferred, combined, compared, or otherwise manipulated. A computer readable medium can be included that is designed to perform a specific task or tasks. Actual computer or executable code or computer readable code may not be contained within one file or one storage medium but may span several computers or storage mediums.
These computer readable instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine such that the instructions will execute on a computer or other data processing apparatus to create a means for implementing the functions specified herein.
Scan unit 26 is in communication with security computer system 24. Fault signals are generated to the security computer when a fault condition arises. As used herein, “fault condition” means a condition in which sensor line 16b has been cut, or damaged in a manner indicating a person has attempted to compromise the cable and tap into the secure data. Scan unit 26 continuously pulses sensor line 16b, in accordance with scanning instructions processed by computer 24. For example, the computer may control the scan unit to pulse the security line every four seconds.
The scan signals 27 are reflected back, and security computer 24 is programmed to compare the reflected scan signals 29 to the baseline signal to determine whether a predetermined signal (attenuation) deviation representing a fault condition has occurred. In the event the fault condition is detected, a fault signal is generated by the computer along with a calculation of the nature and type of the fault and the location of the fault condition. A set of level data can be included in communication with security computer 24. The set of level data may be in the form of a look-up table containing attenuation levels and reflective spikes and corresponding fault information, i.e., break or damage event.
When security computer 24 begins operation, a baseline signal must be established. The baseline signal represents the status of the fiber optic cable being monitored at a normal or undisturbed state. Initially, computer 24 processes baseline initialization instructions, which signal scanning unit 26 to pulse security line 16b. The pulse creates a significant rise in signal level, referred to as a reflective launch spike, preceded by some noise. The normal signal levels start the beginning of the baseline signal. The security computer continues to establish the baseline until a drop to the noise floor occurs indicating the end of the sensor line being scanned. After the drop, further noise occurs. The security computer will then remove a small portion at the beginning of the baseline and a small portion at the end that are merely reflections of the noise launch, and drop. The final baseline signal is then stored for comparison to future attenuations in the sensor line to determine if a fault has occurred.
During the operation, security computer 24 controls scanning unit 26 to continuously pulse sensor line 16b and receive back scan signals representing real-time scans. With each incoming scan signal, the security computer checks to see if any abnormal attenuations are detected. If a significant attenuation change is detected, its location is compared to the baseline signal previously acquired. If the attenuation matches a pre-existing attenuation from the baseline, then the security computer will not report a fault. Any sensor line being pulsed will have some bends and attenuations in its baseline signal. A straight cable extending perfectly vertically from scanning unit 26 will be one of the few instances that no attenuations will be found in the baseline. Thus, every attenuation detected by the computer system will not indicate a fault and may simply indicate a pre-existing bend. Further, some attenuations will be slight, indicating a slight movement of the cable that does not indicate a fault. The attenuations that most concern a user of this system will be those that show a breach or significant damage to the sensor line, and hence a fault condition. In this case, an alarm would be actuated.
As can best be seen in
Surrounding the central rod are buffer tubes 42. The number of buffer tubes is dependent on the number of fibers in the cable. Each buffer tube can accommodate up to 12 communications fibers 44. However, there is a minimum of 5 buffer tube positions to keep the cable round and eliminate a preferential bending direction. If fewer than 5 buffer tubes are required to house communications fibers (44), then the positions are filled with solid plastic filler rods. These rods only serve to take up space that would otherwise be used for buffer tubes and are trimmed away at splice and termination points. The buffer tubes are gel filled. The purpose of the gel is to act as a lubricant to protect the fibers when the cable is in a dynamic state (installation and aerial, windy conditions, for example), and to block water from traveling through the buffer tube should the cable jacket and tube be breached.
The buffer tubes are installed over the central member in a continuous helical pattern. This is in contradiction to standard optical cables used in television and communication cabling that use a reverse-oscillation lay. In the reverse-oscillation lay the helix windings are wound in alternating first and second directions creating a slack space between the windings for splicing, etc. The windings of a continuous helix are all wound in the same direction which is advantageous for the security applications being made according to the invention, and will be described in more detail later. The helical pattern of the buffer tubes, continuous or not, in any fiber optic cable is for mechanical isolation of the fibers from the cable. During installation and operation, the cable may experience tensile loads and thermal contraction that will cause the plastic components of the cable to elongate or shrink more than the glass fibers. The optical performance of the communications fibers is preserved by the fact that the fibers are isolated from these slight changes in the cable length. The communications fibers in the buffer tubes can be of any type that the end user may desire. Common fiber types that are to be used are single-mode, 50 micron multimode, and 62.5 micron multimode, but, again, special and mixed fiber types can be included in the cable.
The buffer tubes are held in place during manufacturing with binder threads 41 that wind in opposite directions over buffer tubes 42. In addition to holding the tubes in place during manufacturing, the binder threads are impregnated with a water-absorbing material. If the cable jacket is breached and water enters the cable, then these binder threads will expand and block the passage of water through the interstitial spaces in the cable. Water in a fiber cable can wreak havoc if the cable is subjected to freezing temperatures since the water will expand and crush cable components and destroy the fragile optical fibers.
An inner cable jacket 46 is the next layer illustrated in the form of a thin polyethylene layer applied over the buffer tubes and binder threads. This inner layer is what an outer cable jacket 48 will adhere to in order to lock the nerve fibers in place. After the inner jacket layer is applied, sensor fibers 50 are placed onto the cable. As can best be seen in
The fibers are preferably of the single mode type. Single mode fiber provides the performance necessary over long distances, which makes this product optimal for long cable installations where other types of security are impossible or impractical. The sensor fiber coating is of a special construction that provides for the mechanical protection needed for a fiber placed inside of the cable jacket. Since there is no mechanical isolation for the sensor fibers as seen with the communications fibers, the fibers need to be reinforced, and this is accomplished by using a fiberglass coating 52.
The final layer in the cable is outer polyethylene jacket 48 over the top of the sensor fibers. This final jacket will adhere to jacket 46 and create a solid jacket with sensor fibers permanently embedded within. Layer 48 completes the illustrated cable design. An option is the addition of metallic armor in the form of aluminum clad steel wires 54 applied in a continuous helix over gasket 46 of the cable. Metallic armor provides mechanical protection from crush and ballistics. allows placement of the cable directly in the ground, on top of the ground, or sub-sea. This armor is significantly different than that found in standard optical cable. Standard optical cable uses a corrugated steel tape that's laminated on both sides for corrosion protection. Standard armor can be (and is designed to be) opened with everyday cable access tools. Outer polyethylene jacket 48 is applied over the wires to complete the armored version. This final jacket provides corrosion protection for the metallic wires.
Security is accomplished by optically monitoring all the sensor fibers embedded in the cable jacket that surround inner communications fibers 44. Monitoring is done with OTDR 26, as explained above in regard to cable A, or other device that will discern disturbances in the fiber path, and computer user interface system B connected to the OTDR. Gaining access to communications fibers 44 in order to tap them requires getting past sensor fibers 50 without disturbing them to the point that the monitoring equipment will detect a fault condition. In addition, in order to place a tap on any of the communications fibers, a length of the fiber long enough to insert into the tap device must be exposed. This will require a displacement of one or more of the sensor fibers, and it is this process that will trigger a fault and an alarm.
The security features of this cable are centered on making displacement the necessary length of sensor fibers impossible without triggering an alarm. The sensor fibers are closely spaced and embedded in and adhered to the polyethylene jacket. The jacket material maintains continuous spacing of the sensor fibers which prevents spreading them apart. The sensor fibers are wrapped in the opposite direction as the buffer tubes. Unwinding the helically stranded buffer tubes to obtain a length of fiber is impossible since the same action would tighten the wind of the sensor fibers. The fiberglass coating on the sensor fibers provides tensile and compression strength necessary for the sensor fibers to remain intact in the cable jacket during normal operation, but cause the fibers to more easily kink if exposed. The buffer tubes are adhered to the fiberglass central member. This makes unwinding the tubes for the necessary slack more difficult without disturbing the sensor fibers.
The cable is designed to meet requirements of TEMPEST which deals with compromising emanations (CE). Compromising emanations are defined as unintentional intelligence-bearing signals which, if intercepted and analyzed, disclose the information transmitted, received, handled, or otherwise processed by any information-processing equipment. Cables can carry unintended signals via metallic components such as conductors or metallic armoring. The cable, without the optional armor, is a dielectric cable, meaning that it contains no metallic components. For this reason, it is impossible for the cable to carry signals outside of the communications fibers. TEMPEST also deals with the possibility of optical signals leaking intentionally or unintentionally from the communications fibers. This is impossible since, according to the invention, the fibers are enclosed in opaque materials. Removal of the opaque materials will trigger an alarm.
Referring to
As can best be seen in
While only a single sensor line 10, 50 is shown connected to a scanning unit schematically, it is to be understood, of course, that the sensor lines may be terminated at one or more scanning units. Preferably, the scanning unit(s) may be provided by an optical time domain reflectometer (OTDR) of the type routinely utilized to monitor maintenance of fiber optic communication systems. The user interface system B may be connected directly to the scanning unit(s) or through an internet or intranet network 27.
Scan unit 26 continuously pulses the optical sensor line 10, 50 in accordance with scanning instructions processed by computer C. For example, the computer may control the scan unit to pulse the sensor line every four seconds. Scan signals 27 are reflected back, and computer C is programmed to compare reflected scan signals 29 to the baseline signal 50 (
When interface system B begins operation, baseline signal 50 must be established. The baseline signal represents the status of the fiber optic cable being monitored at a normal or undisturbed state. Initially, computer C, processing baseline initialization instructions E as shown in
During the operation, the computer system controls scanning unit 26 to continuously pulse optical sensor lines 10, 50 and receive back scan signals 29 representing real-time scans. With each incoming scan signal, the computer system checks to see if any abnormal attenuations are detected. If a fault attenuation is detected, its location is compared to the baseline signal previously acquired. If the attenuation matches a pre-existing attenuation from the baseline, then the computer system will not report a fault. Any sensor line being pulsed will have some bends and attenuations in its baseline signal. A straight cable extending perfectly vertically from scanning unit 26 will be one of the few instances that no attenuations will be found in the baseline. Thus, every attenuation detected by the computer system will not indicate a fault and may simply indicate a pre-existing bend or damage. Further, some attenuations will be slight, indicating a slight movement of the cable that does not indicate a fault. The attenuations that most concern a user of this system will be those that show a breach or significant damage to the sensor line, and hence a fault condition. As can best be seen in
The system and operation is described more fully in U.S. patent application Ser. No. 11/083,038, filed on Mar. 17, 2005, and corresponding PCT Application PCT/US/2005/40079, filed Nov. 4, 2005, herein incorporated by reference.
Thus, it can be seen that an advantageous secure fiber optic data transmission cable can be had according to the invention using fiber optic data transmission line and fiber optic sensor cables. The cable is monitored according to the invention to provide for secure data transmission. An advantageous computerized user interface system and method can be had according to the invention for the fiber optic security system wherein reflected signals from an optic sensor line can be compared to a baseline signal to determine the nature and type of fault condition occurring at any instant corresponding to a prescribed characteristic reflective signal.
While a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.
This application claims the priority and benefit of U.S. application Ser. No. 11/890,450, filed Aug. 06, 2007, entitled Double-End Fiber Optic Security System For Sensing Intrusions, PCT Application serial No.: PCT/US2006/014601 filed Apr. 19, 2006 entitled Secure Transmission Cable; Provisional Application, Ser. No. 60/673,699, filed on Apr. 21, 2005, entitled Secure Above Ground Fiber Optic Data Transmission Cable; PCT Application Serial No. PCT/US/2005/40080, filed Nov. 4, 2005, entitled Apparatus and Method for A Computerized Fiber Optic Security System; co-pending U.S. application Ser. No. 11/083,038, filed Mar. 17, 2005, entitled Apparatus and Method for A Computerized Fiber Optic Security System; PCT Application Serial No. PCT/US/2005/40079, filed Nov. 4, 2005, entitled Vehicle Denial Security System; U.S. Provisional Application Ser. No. 60/626,197, filed Nov. 9, 2004, entitled Vehicle Denial Security System; PCT Application Serial No. PCT/US/2004/013494, filed May 3, 2004, entitled Fiber Optic Security System for Sensing the Intrusion of Secured Locations; U.S. application Ser. No. 10/429,602, filed May 5, 2003, entitled Fiber Optic Security System for Sensing the Intrusion of Secured Locations; and U.S. Provisional Application No. 60/456,687, filed Mar. 15, 2003, entitled Fiber Optic Security System for Sensing the Intrusion of Secured Locations; all of the above applications being incorporated herein by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 60673699 | Apr 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US06/14601 | Apr 2006 | US |
| Child | 11975803 | US |
