FIBER OPTICS TECHNOLOGY AND SYSTEMS IN THE NAVY

DON WILLIAMS

FIBER OPTICS TECHNOLOGY A N D SYSTEMS ZN THE N A V Y

THE AUTHOR

Mr. Don Williams received his BS degree in Electronics Engineering from the Northrop Institute of Technology in 196s. After gmduation he worked for Bourns, Inc., Riverside, Calif., until 1967, develupang automated component test equipment. F r m 1967 to 1970 he was a- ployed at the Naval Weapons Center, Corona, Calif., where he designed TV guidance subsystems. Subse- quent thereto, he joined the Nalml Electronics Labora- tory Center (NELC), San Diego, Calif., where he is presently Head of the Fiber Optics Systems Branch in the Electro-Optics Technology Division and engaged an circuit design, in particular those for Fiber Optic Sys- tems.

ABSTRACT

Fiber optics technology has become a promising candidate to replam metallic wire conductors in many Navy applications. The stimulus behind this is the technical achievements in the reduction of signal attenuation of fiber optics from over lo00 db/km to the recently achieved attenuation factor of under 4 db/km. The Naval Electronics Laboratory, San Diego. is pursuing a technology effort aimed at developing a general set of fiber optics components. These would be the cables in various loss factors; light sources in electm- optic modules for bulkhead mounting to interface with several logic and linear circuit standards; and photo detector modules. The state-of-the-art in the technology and design considerations of interest to naval en- gineers when dealing in fiber optics will be described along with the rationale and justification for using fiber optics in place of metallic wires.

INTRODUCTION

IN RECENT YEARS, FIBER OPTICS TECHNOLOGY has become a very promising candidate to replace metallic

wire conductors in many NAVY applications. The stimuli for this are recent technical achievements in the reduction of signal attenuation of fiber optics and the rapid advances in semiconductor light sources and photode- tectors. The Naval Electronics Laboratory Center in San Diego, as the lead laboratory in fiber optics technology development for the Department of Defense (DOD) , is pursuing both technology development and systems development programs. The technology effort is aimed a t development of a general set of fiber optics components. The systems development efforts range from feasibility demonstrations to direct Fleet support hardware. This paper will introduce fiber optics technology and describe several typical NAVY applications.

It is hoped that this paper will serve to stimulate systems’ users and designers tg consider the potential advantages of fiber optics and to evaluate this technology as it applies to their systems requirements.

Figure 1 shows, in cartoon form, what has been hap- pening to electronics and cable technology over the

Naval Enqimrr Journal. April Im 165

FIBER OPTICS WILLIAMS

1942 1952 1 1962 , 1972

Figure 2. A Typical Conventional Fiber. Figure 1. Electronics and Cable Technology-Where Do We Go After Four Decades?

past four decades. Across the top we see, in the early forties, a rather bulky electronic suite involving large transformers, vacuum tubes and simple interconnects. Later, size was reduced with smaller vacuum tubes and their associated hardware. These were replaced with solid state devices that developed into integrated circuits and finally large scale integrated circuits.

Correspondingly, the complexity of cables is shown to increase tremendously. The situation on the right hand side satirizes the dilemma facing us today. The man holds a large-scale integration circuit which, if interfaced to another remotely located device, could require a standard NAVY cable of the type in his other hand. There are several technologies proposed to re verse this trend. ,We believe fiber optics has the great- est potential for military systems.

There are two basic applications of fiber optics: one is imaging bundles, such as flexible image conduits, faceplates and lenses, and the second is nonimaging “light pipes.” The second type is of principal concern here. In describing these optical waveguides, multi- mode and single mode refer to the modes of energy propagation just as they do in electrical waveguides. The NAVY’S present effort is concentrated in the multi- mode category, where one finds two general signal loss factor divisions : the conventional, or readily available commercial grades, with signal attenuations running between 500 and 1000 decibels per kilometer (db/km), and fibers with losses in the range of 20 db/km or less. The most recent accomplishment in low-loss fibers is less than 2 db/km. Several intermediate loss factors are also appearing in the 100 db/km to 500 db/km range, giving the systems designer considerable flexibility of choice.

In Figure 2 we see a typical conventional fiber which may be from 1 to 3 mils in diameter. Low-loss fibers may be 5 to 7 mils in diameter. Many of these are placed in a fiber “bundle” to offer a large end area to the light emitting and detecting semiconductors and to have redundancy for military systems. The NAVY’S

166 Naval Enpinean Journal. April 1975

technology program has as one of its major goals pro- ducing engineering development model cables of conventional fibers with a loss in the 100 db/km range and low-loss fibers in the under 10 db/km range.

Light propagates through the fibers as seen in Fig- ure 3 because of the difference in index of refraction (n , , n,) between the core glass (center section) and the cladding glass (outer layer), the cladding having the lower index of refraction.

Figure 4 tabulates the comparative features of fiber optics, coax and twisted pair lines. Each line on the chart represents a shared parameter and endeavors to show a fair comparison. For low cost the common factors are: the same cable size, flexibility, equivalent bandwidth and manufacturing quality. The dots sig- nify outstanding or superior features for that particular category.

Fiber optics, coax. or twisted pair offer a fairly even choice in the first four categories. If one wants a low crosstalk or no crosstalk (that is, no measurable crosstalk between adjacent fibers in a fiber bundle), one would have to use fiber optics. Since there is no cross-

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Fiber Optic Light Transmission

Figure 3.

WILLIAMS FIBER OPTICS

ZECFEFTIES OF DATA TRANSMISSION CABLES

LOW COST

TEMPERATURES TO 300 C

VIBRATION TOLERANT LOW CROSS TALK

NO cmss TALI: RF I EM1 NOISE IMMUNITY

1OTAL ELECTRICAL ISOLATION

NO SPARK FIRE HAZARDS

N O SHORT CIRCUIT L O A W G N O RINGIN; ECHOES EMP IMMUNITY

TFMPERATURES TO 1 0 0 O C NO CONTACT OISCONTIN1IITY

SIGNAL BANDWIDTH 200 Y

NELC y. m u

Figure 4. Comparative Features of Fiber Optics.

talk between adjacent fibers, there is certainly no crosstalk between adjacent fiber cables.

Fiber optics, being made of glass, a dielectric, provide ideal RF’I/EMI noise immunity. They do not pick up nor do they radiate any signal information.

Fiber optics also provide total electrical isolation between the sending and receiving terminals, eliminating any common ground and the problems that are associated with common grounds (voltage offsets, ground currents, ground noise, pickup, etc.) .

There are no spark or fire hazards with fiber optics, should the fiber optics be damaged. There is m local secondary damage incurred because no sparking, heat, or energy dissipation of any sort takes place.

There can be m short circuits or circuit-loading re flections back to the terminal equipment if a fiber optic cable should be damaged. In wire systems the damage to a cable may cause reflected damage into the terminal circuits by shorting, grounding, or dangerous po- tentials and currents in the wires. The fibers do not conduct electrical current and thus eliminate this problem.

Fiber optics have EMP immunity for the same reason they have RFI/EMI immunity. Experiments on nuclear radiation hardening or radiation hard fibers are finding some fiber optic materials presently manu- factured that offer very good radiation hardening for manned as well as unmanned environments.

Wire systems suffer from connector discontinuity problems because of the need for good physical contact a t connector interfaces for signal transfer. Proper choice of the optical interface between light source or detector and the fiber optic bundle provides a signal junction requiring no physical contact. The light energy signal passes through the small air gap between these devices and the end of the fiber optic bundle.

Tests have shown that most liquid “contaminants” found in NAVY aircraft increase signal coupling when placed in this interface. Grits and opaque materials can, however, decrease transmission or damage connector surfaces if proper procedures are ignored.

Temperatures up to 1,O0OoC may be withstood by

certain glass systems. Most present glass flbers are stable well beyond 300°C.

Assuming an acceptable flber loss factor in the range of 50 db/km, one Ands a 200 megahertz limit with 5ber oQtics for a 300 meter length. This is primarily a function of the electro-optic devices available, either the directly modulated light emitting diode (LED) or the laser beam acousto-optic modulators. Coax, according to handbook data, is limited to 20 megahertz for the same cable size and length, and a twisted wire pair to one (1) megahertz. Fiber optic systems with band- widths over 100 megahertz should be considered laboratory systems a t present, and not quite ready for deployment. Potential signal bandwidth with single mode fibers is calculated to be above one (1) Gigahertz.

Three types of signal multiplexing may be considered for fiber optics. Electronic parallel to serial (P/S) or time division multiplexing may be used to obtain a serial format of many parallel signals for single channel fiber optics communication. An example of this will be described later for a NAVY data cable. As we now know, there is no measurable crosstalk

between adjacent flbers in a bundle and thus no crosstalk between groups of fibers. The fiber optic bundle may thus be subdivided with each group of fibers being a separate, parallel, channel. This concept may be ex- tended to a single fiber per channel if one can afford to give up the redundancy in a group of flbers.

Light sources with different wavelength characteristics (colors) may be employed to add to the data capacity of a flber optics. This wavelength (or carrier frequency) “multiplexing” allows several channels to be carried on a flber bundle, subgroup of fibers, or even on single fibers. Practical limits are presently about five colors in the range from visible red (-6500A) to the near infrared (-9300A). Various combinations of all three “multiplexing” techniques may be used to en- hance greatly the data capacity of fiber optics.

Figure 5 is a block diagram of a typical fiber optic system. In this case, we have depicted a digital signal; however, the system could transmit an analog signal as well. Depending on the bandwidth and current levels required for the type of Light Emitting Diode (LED) used, the driver could be as simple as a single transis-

TYPICAL SYSTEM

+ + I LED 1 PHOTODIODE

- - AMPLIFIER

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Figure 5. Block Diagram-Typic81 Fiber Optics System.

167 Naval Enpinoon Journal. April 1975


tor. For high speed operation one would use more complex amplifiers. The intensity of light output from the LED is proportional to the current through it. Thus, the amplifier output current controls the light intensity. In this particular application, a Zugic one would be the LED “on” state (light on), and a logic zero would be LED “off’ (no light output). The light coming from the LED enters the fiber optic bundle and propagates through the bundle to the photodiode a t the receiving end. The photodiode signal current is proportional to the amount of light impinging oh it, and this is sensed by the load resistor. This signal is amplified and shaped for the particular type of output required.

Figure 6 is an artist’s conception of a singlebundle in the upper cable drawing and a multiple bundle (four-bundle) cable in the lower drawing. These are representative of fully armored cables under development in NELC’s fiber optics technology program. The packaging and armoring materials and the connectors may be quite similar to existing wire cable protective materials and types ; emphasis is, however, being placed on developing completely nonconductive protective jackets to satisfy Red/Black Secure Criteria and to re- move any possible electrical path along the cable.

‘15€R C?PTIC CGSCES AYC) CONNECTORS -

NELC m moD -~ _ _ ~ _ ~ - -

Figure 6. Artist’s Conception of a Single-Bundle and Multiple-Bundle Cable.

The four-bundle cable is shown with bundle separation throughout, but may be mixed along the cable because there is no crosstalk problem. End identification and separation of channels is all that is required for multibundle cables. If splicing or similar repairs are anticipated, the cable channels should be physically separated throughout t&-maintain identification and to allow efficient repair.

Figure 7 is a line drawing of the standard fiber optic/ electronic interface module being developed in NELC’s fiber optics technology program. The ex- ploded view shows the basic components used in the Light Emitting Diode/Driver Module (the transmitting end of a fiber optic system). This basic module design will be used for several standard electronic interface

units, each having a Light Emitting Diode (LED) and matching drive circuits optimized for its particular logic or analog family type.

The first generation of MIL-qualified modules are being developed for direct compatibility with tran- sistor-logic (TTL) circuits. Future module families will be developed for direct compatibility with other logic and analog interfaces.

The first preproduction TTL source modules have successfully passed MIL-E-5400P, Class I1 aircraft environmental testing (temperature range -62” C to +95” C, altitude to 70,000 feet, humidity to 90%, vibration, 10 Hz to 2000 Hz). Production quantity modules should be available in June of this year; TTL compatible detector modules about six months behind the source units in their development phases.

The module would be assembled using the parts selected for the particular “family member” a t the factory. The modules are planned to be a disposable or throw-away item in the event of a component failure. In the upper left hand corner of Figure 7 one sees a cable connector with this bulkhead mounted module. The module would protrude behind the bulkhead approximately %’‘ including the pins. The module diameter behind the bulkhead would be approximately 0.3 of an inch. A family of modules is planned for the receiving terminal similar to the transmitting modules for each family in which a photodiode would replace the LED in the drawing, and different electronics would be designed for the receiving function. The modules contain all the circuits and components required for direct connection to the logic family or analog type specified.

The interface approach has several advantages as a fiber optic interface, such as:

1) Elimination of contact discontinuity at the “break point” because of the optical coupling instead of electrical contact.

2) Throw-away modularity. 3) Diode-to-circuit matching and engineering is no

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B U I K I I I A O amC1DR NELC 6. i r

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Figure 7. Standard Fiber OptidElectronic Interface Module.

168 Naval Enginwrr Journal. April 1975


longer the systems designer’s problem. 4 ) Easy to install and replace. 5) Update to newer replacements is extremely sim-

ple.

Several standard environmental tests were performed on fiber optic bundles to draw a comparison with the metallic counterparts: TWISTED PAIR and COAX CABLE. Two loss grades were tested: the Galileo bundle with a loss of 500 dbi km and a Corning bundle with a loss of 70 dbikm. An outstanding feature of the 500 db/km fibers is the cyclic flexibility. This cable survived, without any fibers being broken, 30,000 cycles in which it was bent through k 9 0 ” about onehalf inch mandrels placed on opposite sides of the test bundle. Should one submit any of the metallic wire types to this same test, they would “work-harden’’ and fail before 30,000 cycles. The low-loss cable did not per- form as well (1000 cycles/ 2 inch mandrels). The low- loss development for the test specimen, however, was not as advanced as the 500 dbikm sample. The low- loss technology effort has been concentrated on reduc- ing losses. Environmental aspects are now being worked on to improve this situation.

The twist tests are significant when compared with metallic conductors. For a 10% breakage level, the 500 dbikm fibers withstood seven 360’ rotations or twists per foot. One would not be able to do this to a soft dielectric coax or twisted pair without incurring a failure more critical than 10T signal loss.

NELC has developed termination tooling for splicing fiber optic bundles which requires little skill to use and makes the job quite simple. A splice is made as follows :

1) Strip I/*’’ of PVC jacket from end of bundle. 2) Apply a small amount of quick-setting epoxy to

the PVC jacket around the end. 3) Slide the metal ferrule over the fibers and jacket

until firmly seated on the jacket. 4 ) Apply a drop of quick-setting epoxy to the fibers

protruding from the narrow end of the ferrule (capil- lary action will cause epoxy to fill voids between fibers and ferrule).

5 ) Use motorized tool to finish end of termination.

The battery-powered grinding and polishing tool (Figure 8) has three ports designed to accept the termination ferrule. The three finishing steps can be accomplished in less than one minute after the epoxy has set, which also takes less than one minute.

This procedure is followed for both ends of an “in- line” splice, and the two end termination ferrules are inserted into opposite ends of a sleeve to butt the fiber ends together. It is sealed by the same epoxy applied just prior to insertion in the sleeve.

With conventional medium-loss (500 db/km) flbers the “in-line’’ splice will produce a 3 db signal loss. The packing fraction (individual fiber to fiber align- ment) at the butt joint is the major contributor to this loss. Systems are typically designed to allow for a few

FIBER OPTICS GRINDER AND POLISHER

6Rm01N6 WHEEL

PORT C

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Figure 8. Battery-Powered Grinding and Polishing Tool.

“in-line’’ splices during their lifetimes. Improved techniques are under investigation to reduce the splicing loss.

SYSTEMS APPLICATIONS

Figure 9 shows two cables. The outer cable is a standard NAVY data cable consisting of 45 shielded, twisted-pairs and is used for parallel transmission of computer information. The center dual cable serves the same purposes. However, it is fiber optics. The reduction in cable size must be attributed to the elec-

Figure 9. A CemparisonStandard Navy Data Cable VB Fiber Optics Dual Cable. (Official U.S. Navy Photo)

Naval Engirmrr Journal, April IT7S 169


tronics inside the connectors. We are dealing with parallel electrical information, but it is much easier to transmit the information over a single fiber optic channel in serial format. To do this, the electronics contained in the connector on the left converts the 36 parallel lines to a serial format at a higher data rate (serial data clock 10 MHz.) Inside the connector neck this serial electronic s i g a l is converted to an optical signal using a light emitting diode. The signal then propagates through the fibers and is detected in the other connector housing where the light signal is detected, converted to an electrical signal, and recon- verted from the serial back to the original parallel format. The second fiber optic bundle is for an ac- knowledge signal which is sent back to the transmitting end of the cable. This cable was tested with the Message Processing and Distribution System (MPDS) and functioned as well as the wire cable. This was a feasibility demonstration using a plug compatible retrofit. Significant additional savings could be realized if the electronic multiplexing were packaged inside the equipment. The 36-line driver and receiver circuits necessary to drive the wire cable would be eliminated, as would the 90-pin electrical connector interface. Proper application of this advanced concept would have a fiber optic cable to equipment mounted module interface.

Figure 10 shows a block diagram of the fiber optic secure phone system. This is a six station telephone network on board the U S S Little Rock (CLG-4). Fiber optics were used for secure communications because they have no signal leakage and are thus TEMPEST qualified under ship-board criteria. The phones are located in the Intelligence Office, Flag Plot, Chief of Staff Office, Supplemental Radio (SUPRAD) -which also contains the central switching station, and there are two phones in the Combat Information Center (CIC) complex. This system has been deployed for one and one-half years and has been favorably com-

I FLAGSHIP 6th FLEET SECURE SIX STATION PHONE SYSTEM

s202

INTEL F l

I FIBER OPTIC CABLE i FOR TEMPEST SECURITY

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Figure 10. Block Diagram-Fiber Optic Secure Phone System.

Figure 11. Bulkhead-Mounted Terminal in the Fiber Optic Telephone System. (Official US. Navy Photo)

mented on by Commander SIXTH Fleet. The photograph (Figure 11) shows one of the tele-

phones in the system. The phone’s appearance is similar to standard NAVY sound-powered phones and was designed to operate as in a normal Intercom System. The phone system will allow three simultaneous two- way conversations. The fiber optic cables come out of the top of the phone box and may be seen strapped against the bulkhead. In this application we used the conventional fiber optics having a loss of 500 db/km. These are jacketed with PVC plastic and have no armoring on them. Future applications, of course, will use armoring as it is developed in the technology program. This system used circuit box modules to prove the module concept previously described and now being developed in the technology program.

SUPRAD contains the central switching station through which all calls are routed. There are six but- tons on the switching station that may be used to eliminate any phone from the link. If one attempted to use such a phone, he would only get a busy signal, as would anyone attempting to reach him.

Optical signals arriving in the fiber optic bundle from the calling station are detected and converted to electrical form a t the central switching station. These TTL logic-compatible signals are processed and di- rected to the phone station being called. They exit the central switching station again as optical signals in fiber optic bundles. At the “called station” the optical signals are detected and demodulated to produce the

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FIBER OPTK CABLE PllOTS M O V Rooy FOR EM! RFI ENVIRONMENT

Figure 12. Fiber Optic Closed-Circuit TV System-Artist's Conception. audio signal for the handset receiver. Full duplex operation is accomplished by using a pair of these signal paths in both directions for each phoneyink.

An artist's conception of the fiber optic closed-circuit TV system installed on the USS Kittyhawk is shown in Figure 12. The purpose for using fiber optics in this particular installation was to demonstrate cable immunity to the RF'I/EMI environment. The television camera is in the Integrated Operations In- telligence Center (IOIC) complex, and the monitor is in Pilot's Ready Room No. 9. No problems were en- countered installing the PVC jacketed low-loss fiber bundles on the ship.

The actual fiber optic closed-circuit television system hardware is shown in the photograph in Figure 13. From left to right are the TV camera, the video- modulated light circuits, 300 feet of low-loss (60 db/km) fiber optic cable, the fiber optic receiver and TV monitor. This system uses a pulse frequency modu-

lation technique to demonstrate also the bandwidth capabilities of the fiber optics and to reduce the effect of dynamic range and linearity limitations of the light emitting diode (LED). The video modulated circuits use an Emitter Coupled Logic (ECL) oscillator cen- tered a t 44.3 MHz which is frequency modulated by the composite video. This signal is converted to a light signal for transmission through the flber optic bundle. At the receiver a photo detector reconverts the signal to the electrical format and a phase locked loop re- covers the composite video for the monitor.

The video display was clearer and more noise-free than the coax wire system it duplicated. This was due to the electrical isolation and the EM1 immunity of the fiber optics.

Figure 14 is a pictorial view of the A-7 aircraft showing the approximate location of the avionics associated with the Navigation and Weapons Delivery

FIBER OPTICS A 7 AIRBORNE L I G H T OPTICAL FIBER TECHNOLOGY ALOFT DEMONSTRATION

Figure 14. A-7 Aircraft Avionics Associated With NWDS (Navigation and Weapons Delivery System).

Figure 13. Fiber Optic Cloeed-Circuit TV System Hardware. (Official U.S. Navy Photo)

Naval Enqimen Journal. April IT7S 171


System (NWDS). NELC is currently managing a program to replace all the signal wiring in the NWDS with fiber optics and, in several instances, to use data multiplexing. The combination of data multiplexing and fiber optics will reduce the number of point-to- point signal channels from approximately 309 to 13. The A-7 will benefit greatly from the elimination of electromagnetic interference, the primary reason for fiber optics in aircraft. The savings in weight and component costs are a comparison between the fiber optics cables and their connectors and the original wires and connectors that are replaced. The addition of electronics for the signal multiplexing requires fewer circuit packages and less power than the multi- channel line drivers and receivers used in the present wire configuration.

A one-on-one comparison of the fiber optics cables and wire equivalents in the multiplexed configuration is as follows:

Figure 15. RFI Screen Room Tests During EM1 Tests Associated With NWDS.

13 cables (average 20 feet each), 10 MHz Data. Fiber optics 3.6 pounds RG-142 coax 12.0 pounds T-43 Twisted pair 35.6 pounds

This is a two year program culminating in a com- plete flight test to exercise fully the entire Navigation and Weapons Delivery System (NWDS) with the fiber optics.

A predecessor to the A-7 program, the EM1 tests, was performed on the ASN-91 computer to Head-Up Display (HUD) of the NWDS. A fiber optic system was spliced into this 4-channel link in the simulation laboratory. Under normal operating conditions there was no visible difference in operation of the HUD when connected to the computer through the fiber optic link or a conventional shielded-wire cable.

The photograph in Figure 15, is a picture of the RFI screen room tests that were performed in this demonstration. The wiring from the ASN-91 computer of the NWDS to the Head-Up Display (HUD) electronics was replaced with fiber optics. This spliced-in system replaced four twisted shielded pair signal lines by multiplexing the data to serial format, converting it to an optical signal, sending it through 50 feet of fiber optics (which is 15 feet more than the maximum length required in the A-7), detecting the light signal at the receiving terminal, reconverting it to the electronic signal, and reconverting to the original parallel format of four twisted shielded electrical lines. The conversion electronics as well as the fiber optic cable were completely tested to Methods RE02 and RS03 of MIL-STD-462 and to radiated limits specified in MIL-STD-461. Radiated susceptibility field strengths per MIL-STD-461, RE02 are as follows:

The net results were that the fiber optics system could not be disturbed or penetrated, and no noise signals could be detected on the logic coming out of the system with the specified frequencies and field strengths. Conversely, we could not measure any emanations from the system for the same frequency spectrum. This test confirmed not only that fiber optics are inherently immune to RFI, but it also proved the EM1 performance of the included connector apertures (their waveguide filter effect a t the particular frequencies of interest), the packaging, and shielding of the electronic interfaces and multiplexing circuits.

Figure 16 shows the multiplexer and demultiplexer boxes in the foreground with the fiber bundle. In the background is a lucite box containing a Tesla coil, a generator of electrical noise having a wide frequency spectrum. The Tesla coil produces a visible arc from its tip to the aluminum block such that the arc goes directly through the fiber bundle. The only result of the arc is to melt the PVC jacket after long exposure. The arc causes no interference in the operation of the

14 KHZ to 35 MHz - 10V/M

35 MHz to 10 GHz - 5V/M Figure 16.

172 Naval Enqinoor$ Journal, April I975


Head-Up Display (HUD) . The HUD operation is “rock solid.” To demonstrate the effect of this energy on the aircraft wiring, the original wire cable was exposed to the Tesla arc. This was done by placing the wire cable through the trough at the base of the aluminum, 3 l i inches from the arc and insulated from the block. The EM1 induced in the cable (four twisted shielded pairs plus a gross shield) was enough to make t h e Head-Up Display bounce around to the point tha t one could not recognize or locate the symbols. We also know that if t he gross shield is removed from the twisted shielded pairs, one could only get within 18 inches of the arc before the transients would erase the memory of the ASN-91 computer.

SUMMARY

Fiber optics is truly becoming a viable candidate for internal communications for the military. The inherent advantages and the rapid development of technology, hardware, and systems applications are of great significance to the Naval Systems Engineer.

Many programs and developments are now under way to expedite t he use of fiber optics in the NAVY; f a r too many to cover in this introductory paper.

Fur ther information and reports on the technology development, environmental test programs, or systems application projects are available through the Author.

BIBLIOGRAPHY

[11 Churchill, R. A., and K. Avicola, “Wideband Fiber Optic Analog Information Link.” Aittonetics, Sep- tember 1969.

[21 Control Data Corporation, A-7 Aloft Demonstration Program Plan, N00123-73-C-0141.

[31 Damari, A. D., H. H. Bloem, D. J. Stigliani. Jr.. R. C. Clapper and H. C. Farrell, High-speed Optical Data Link f o r Interronnection Between L S I Moddes . New York: IBM, Federal Systems Division, Final Report (March 1972---March 1973 1 .

[41 Eastley. R. A.. and W. H. Putnam, Fiber Optic I n - terconnectwns for 2KSES Electrowic Systems. Naval Electronics Laboratory Center, TD 333, March 1974.

[51 Eastley. R. A., and W. H. Putnam, Telephone Sys- tem-Fiber Optic Model S202. Naval Electronics Lab- oratory Center, TD 260. Preliminary Technical Manual NSAP Task S-9-72 (19 July 1973).

[61 Farrell, H. C.. and R. N. Jackson, EMI Tests o f a Flber Optic. Data Link and A-7D/E Bench Tes t Demonstration. New York : IBM. Federal Systems

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1231

Division, Final Report ( February-May 1973). Howard, E. A., and D. H. Marcus, Fiber Optic Data Bits. Naval Electronics Laboratory Center, TR 1921 t 29 April 1974). IBM Electronics Systems Center, Z,ight Interface Tech m b g y Improvement Investigation, Volume 111, 30 September 1971. IBM Electronics System Center, WaLvlength Di- risio)i M i t l f i p k r i n g in Light Interface Technology. Progress Report, N00015-71-C-0012, Volume 11. Independent Research and Independent Explanatory Dewlopment . Naval Electronics Laboratory Center, Annual Report Fiscal Year 1972 (1 September 1972). Kosmos. G.. The Eflects o f Contaminants on Fiber Optic Connector Radiation Patterns. Naval Elec- tronics Lahoratory Center, TD 349 (25 July 1974). Lcbduska. R. L.. and G. M. Holma. Fiber Optic Cable Hardware Test . Naval Electronics Laboratory Cen- ter, TR 1900 (11 December 1973). Lebduska. R. L.. FLber Optic Cable Tes t . Naval Electronics Laboratory Center, TR 1869 (12 March 1973 I . Light Interfuce Technology ( L I T ) . IBM File No. 69-947-047, IBM Federal Systems Division, Mary- land. Nuese. C. J.. A. G. Sigai. and I. Kudman. High- Brigh f w s s Electroltimenescent Diodes. RCA, Annual Report, N00014-71-C-0198 ( 1 January-31 December 1971). Parsons. S. R.. D. J. Stigliani. R. C. Clapper, and D. W. Hanna. High-speed Optical Data Links. New York : IBM Federal Systems Division, Final Report (17 January 1971-17 January 1972). Shuhert, J. C., InstaUation and Tes t s o f LIT in Heli- copter System. New York: IBM Federal Systems Division ( 14 November 1974). Stigliani. D. J., Jr.. Performance Characteristics of (( Fiber Optic Commitnication Link. New York : IBM Electronics Systems Center, March 1972. Stigliani. Daniel J.. Jr., Light Interface Technology Znip r o i w n e n t I n vest igat ions. Monthly Status Report for July 1971, Volume I. IBM Corporation. Stigliani. Daniel J.. Jr.. David W. Hanna. and Robert J. Lynch, Wavelength Division Midtipkxing in Light Interftlre Tech.nology. New York : IBM Electronics System Center (19 March 1971). Stotts, L. B., A. L. Lewis, and V. N. Srniley. Fiber Optic B m d k Transmission Characteristics. Naval Electronics Laboratory Center, TN 2265 (16 Novem- ber 1972). Taylor. H. F.. W. M. Caton. and A. L. Lewis, Fiber Optics Data Bus System. Naval Electronics Labora- tory Center, TR 1930 (26 August 1974). Taylor, H. F., Transfer of Information on Naval Vessels ria Fiber Optics Transmission Lines. Naval Electronics Laboratory Center. TR 1763 (3 May 1971).

Marine Technology Ship Systems Electronic Systems . Micrographics . Logistics . Management Systems . Documentation Engineenng

~ E H N I G A L APPLICZITIONS, INC. San Diego (74) 2784273 . Los Angela (213) 473-2991 . McLem (703) 893-18oc Norfolk (804) 853 2M1 Huntsville (205) 881-2265

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FIBER OPTICS TECHNOLOGY AND SYSTEMS IN THE NAVY

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