Glossary

AI-1

Appendix I

GLOSSARY ACTIVE SATELLITE—A satellite that amplifies the received signal and retransmits it back to earth. AFDS—An abbreviation for the amphibious flagship data system. ANGLE OF INCLINATION—The angular difference between the equatorial plane of the earth and the plane of orbit of the satellite. ANTENNA COUPLER—A device used for impedance matching between an antenna and a transmitter or receiver. APOGEE—The point in the orbit of a satellite the greatest distance from the earth. ASSEMBLY—A number of parts or subassemblies, or any combination thereof, joined together to perform a specific function.

ASWTDS—An abbreviation for the antisubmarine warfare tactical data system. ASYNCHRONOUS ORBIT—One where the satellite does not rotate or move at the same speed as the earth. ATDS—An abbreviation for the airborne tactical data system. AUDIO FREQUENCY TONE SHIFT—A system that uses amplitude modulation to change dc mark and space impulses into audio impulses. AUTOMATIC TRACKING—Tracking done by the equipment comparing the direction of the antenna axis and the direction of the received signal. AUTOMATIC VOLUME/GAIN CONTROL—A circuit used to limit variations in the output signal strength of a receiver.

BALANCED PHASE DETECTOR—A circuit that controls the oscillator frequency (afc). BAUD—A measurement of speed based on the number of code elements or units per second. BEAT-FREQUENCY OSCILLATOR—An additional oscillator used in a receiver when receiving a cw signal. It provides an audible tone. BITS-PER-SECOND—Bit is an acronym of the words binary digit. One bit is equal to one signal unit or element. BLACK—The reference color of equipment that passes unclassified information. It normally refers to patch panels. CODE—In teletypewriter operation, code is a combination of mark and space conditions representing symbols, figures, or letters.

COHERENT—Radiation on one frequency. AI-2 COMPARATOR—An equipment that compares incoming signals and selects the strongest to be fed to a teletypewriter through a patch panel. This is used in diversity operation. CONVERTER—An equipment that changes the audio output of a receiver to dc pulses. These pulses are fed to a tty to indicate marks and spaces. DETECTION—The separation of low-frequency (audio) intelligence from the high (radio) frequency carrier. DOUBLING UP—This is a type of two-equipment installation where one unit can be substituted for another in the event of failure.

DOWN LINK—The frequency used to transmit an amplified signal from the satellite back to earth. DUMMY LOAD—A nonradiating device that absorbs the rf and has the impedance characteristics of the antenna. ECLIPSE—This occurs when the satellite is not in view or in direct line of sight with the sun. This happens when the earth is between them. ELECTROMAGNETIC INTERFERENCE—A term used to describe the degradation of a receiver or system. EPHEMERIS—A table showing the precalculated position of a satellite at any given time.

EQUATORIAL ORBIT—An orbit that occurs when the plane of a satellite coincides with the plane of the earth at the equator. EXTREMELY HIGH FREQUENCY—The band of frequencies from 30 gigahertz to 300 gigahertz. EXTREMELY LOW FREQUENCY—The band of frequencies up to 300 hertz. FACSIMILE—The method for transmitting and receiving still images. These images can be maps, photographs, and handwritten or printed text. FADING—The variations in signal strength at the antenna of a receiver. FIBER OPTICS—Conductors or optical waveguides that readily pass light.

FIDELITY—The ability of a receiver to accurately reproduce, at its output, the signal at its input. FORWARD AGC—The type of agc that causes an amplifier to be driven towards saturation. FRAMING—The process of synchronizing a facsimile receiver to a transmitter. This allows proper picture reproduction. FREQUENCY-DIVISION MULTIPLEXING—Multiplexing that transmits and receives the full 360 degrees of each sine wave. FREQUENCY SYNTHESIS—A process that uses hetrodyning and frequency selection to produce a signal. FREQUENCY SYNTHESIZER—A frequency source of high accuracy.

GANGED TUNING—The process used to tune two or more circuits with a single control. AI-3 GROUP—A collection of units, assemblies, subassemblies, and parts. It is a subdivision of a set or system but is not capable of performing a complete operational function. HAND OVER—The operation where one earth terminal yields control to another as a satellite moves out of its area of coverage. HARMONIC—An exact multiple of the fundamental frequency. Even harmonics are 2, 4, and so on, times the fundamental. Odd are 3, 5, and so on, times the fundamental frequency.

HELIX—A large coil of wire. It acts as a coil and is used with variable inductors for impedance matching of high-power transmitters. HELIX HOUSE—A building at a transmitter site that contains antenna loading, coupling, and tuning circuits. HETERODYNING—The mixing of the incoming signal with the local oscillator frequency. This produces the two fundamentals and the sum and difference frequencies. HIGH FREQUENCY—The band of frequencies from 3 megahertz to 30 megahertz. IMAGE FREQUENCY—An undesired frequency capable of producing the desired frequency through heterodyning.

INCLINED ORBIT—Orbits where there is some amount of inclination. These include equatorial and polar orbits. INCOHERENT—This refers to radiation on a broad band of frequencies. INTELLIGENCE—Any signal that conveys information (voice, teletypewriter, facsimile). KEYER—A device that changes dc pulses to mark and space modulation for teletypewriter transmissions. LASER—An acronym for light amplification by stimulated emission of radiation. LISSAJOUS PATTERN—A combined, simultaneous display of the amplitude and phase relationships of two input signals on a CRT.

LOW FREQUENCY—The band of frequencies from 30 kilohertz to 300 kilohertz. MARKING—The state where a circuit is closed and current flows in teletypewriter operation. MEDIUM ALTITUDE ORBIT—An orbit from 2,000 to 12,000 miles above the earth. The rotation rate of the earth and satellite are quite different, and the satellite moves quickly across the sky. MEDIUM FREQUENCY—The band of frequencies from 300 kilohertz to 3 megahertz. MTDS—An abbreviation for the marine tactical data system. MULTICOUPLERS—Couplers patch receivers or transmitters to antennas. They also filter out harmonics and spurious responses, and impedance-match the equipment.

MULTIPLEXING—A method for simultaneous transmission of two or more signals over a common carrier wave. AI-4 NEAR SYNCHRONOUS ORBIT—An orbit in which the satellite rotates close to but not exactly at the same speed as the earth. NEUTRAL—The teletypewriter operation where current flow represents a mark and no flow represents a space. NOISE SILENCER, NOISE SUPPRESSOR, OR NOISE LIMITER—Circuits that clip the peaks of the noise spikes in a receiver. NONSYNCHRONOUS—The teletypewriter operation where both transmitter and receiver do not operate continuously ORDER-WIRE CIRCUIT—A circuit between operators used for operations control and coordination.

PAGE PRINTER—A high-speed printer that prints teletypewriter characters one at a time in a full-page format. PASSIVE SATELLITE—A satellite that reflects radio signals back to earth. PATCH PANEL—A panel used to tie a receiver or transmitter to its associated equipment. PART—A part is one component or two or more components joined together. It is not normally subject to disassembly without destruction. PERFORATOR—A device that stores a teletypewriter message on a paper tape. It may be stored for later transmission. PERIGEE—The point in the orbit of a satellite closest to the earth.

PERMANENT MAGNET SPEAKER—A speaker with a permanent magnet mounted on soft iron pole pieces. POLAR—The teletypewriter operation where current flow of one polarity represents a mark and current of the opposite polarity represents a space. POLAR ORBIT—An orbit that has an angle of inclination of or near 90 degrees. PROGRAMMED TRACKING—The method that uses known satellite orbital parameters to generate antenna pointing angles. RADIO COMMUNICATIONS—The term describing teletypewriter, voice, telegraphic, and facsimile communications.

RADIO FREQUENCY CARRIER SHIFT—The system that uses a keyer to shift a radio frequency signal above or below an assigned frequency. These shifts correspond to marks and spaces. RADIO SET CONTROL UNIT—Equipment used to remotely control certain transmitter and receiver functions. RECEIVER—Equipment that converts electromagnetic energy into a visible or an audible form. RECEIVER TRANSFER SWITCHBOARD—Equipment used to transfer receiver audio outputs to remote control station audio circuits. AI-5 RECEPTION—The instant when an electromagnetic wave passes through a receiver antenna and induces a voltage in that antenna.

RED—The reference color of equipment that passes classified information. It normally refers to patch panels. REPEATER—Another name for an active satellite. REPERFORATOR—Equipment that converts the incoming tty signal and stores it on paper tape. REPRODUCTION—The process of converting electrical signals to sound waves. This sound is speech, music, and so on. REVERSE AGC—The type of agc that causes an amplifier to be driven toward cut-off. RUNNING OPEN—The teletypewriter condition where the type hammer constantly strikes the type box but does not print or move across the page.

SATELLITE ECLIPSE—An eclipse where the rays of the sun don't reach the satellite. This prevents recharging of the solar cells of the satellite and decreases the power to the transmitter. SATELLITE-SUN CONJUNCTION—A period when the satellite and sun are close together and the noise from the sun prevents or hampers communications. SCANNING—The process of subdividing a picture in an orderly manner into segments. This is used in facsimile transmission. SELECTIVITY—The ability of a receiver to select the desired signal and reject unwanted signals.

SENSITIVITY—The ability of a receiver to reproduce very weak signals. The greater the receiver sensitivity, the weaker the signal that will be reproduced. SET—A unit or units and the assemblies, subassemblies, and parts connected or associated together to perform a specific function. SPACING—The condition in teletypewriter operation where a circuit is open and no current flows. SQUELCH—A circuit that cuts off the output of a receiver when there is no input. START—The first unit of a teletypewriter signal. It is always a space.

STOP—The last unit of a teletypewriter signal. It is always a mark. SUBASSEMBLY—Consists of two or more parts that form a portion of an assembly or a unit. SUBHARMONIC—An exact submultiple of the fundamental frequency. Even subharmonics are one- half, one-quarter, and so on. Odd subharmonics are one-third, one-fifth, and so on of the fundamental frequency. SUPERHIGH FREQUENCY—The band of frequencies from 3 gigahertz to 30 gigahertz. SUPPRESSION—The process of eliminating an undesired portion of a signal. SYNCHRONOUS—A type of teletypewriter operation where both transmitter and receiver operate continuously.

AI-6 SYNCHRONOUS ORBIT—An orbit in which the satellite moves or rotates at the same speed as the earth. SYSTEM—A combination of sets, units, assemblies, subassemblies, and parts joined together to form a specific operational function or several functions. TELECOMMUNICATIONS—The transmission, emission, or reception of signs, signals, writings, images, or sounds. This is done by visual, oral, wire, radio, or other electromagnetic means. TELETYPEWRITER—A machine that can transmit and or receive letters, numbers, or symbols. It may have a keyboard similar to a typewriter.

TEMPEST—A term normally used to describe compromising emanations. These emanations are unintentionally radiated signals that could disclose classified information. TIME-DIVISION MULTIPLEXING—The process that periodically samples the full 360 degrees of each sine wave. The sample can be of a received signal or of a signal to be transmitted. TONE-TERMINAL SET—Equipment that converts tty dc pulses into audio tones for modulation of a transmitter in audio-frequency-tone shift transmissions. TOP-HAT—An antenna that is center-fed and capacitively loaded.

TRANSITION—The time it takes to shift from a mark to a space condition or from a space to a mark condition. TRANSMITTER—Equipment that generates and amplifies an rf carrier, modulates the rf carrier with intelligence, and radiates the signal into space. TRANSMITTER DISTRIBUTOR—A device that reads Baudot code from paper tape and allows a message to be printed on a page printer. TRANSMITTER TRANSFER SWITCHBOARD—Equipment that selectively transfers remote control station functions and signals to transmitters. TRIATIC—A special type of monopole antenna array.

ULTRAHIGH FREQUENCY—The band of frequencies from 300 megahertz to 3 gigahertz. UNIT—An assembly or any combination of parts, subassemblies, and assemblies mounted together. Normally capable of independent operation. UP LINK—The frequency used to transmit a signal from earth to a satellite. VERY HIGH FREQUENCY—The band of frequencies from 30 megahertz to 300 megahertz. VERY LOW FREQUENCY—The band of frequencies from 3 kilohertz to 30 kilohertz. WORDS-PER-MINUTE—An approximate rate of speed. It means the number of five letter words with a space between them that can be transmitted or received in a one-minute period.

ZONE OF MUTUAL VISIBILITY—The area where the satellite can be seen by both the up- and down-link earth terminals. AII-1

Appendix Ii

Reference List

Chapter One

ELF Communications System Program, NAVELEXINST 5430.26, October 1983. Shipboard Electronics Materials Officer, NAVEDTRA 10478-A, 1982. Electronics Technician, 3 & 2, Vol. 3, NAVEDTRA 10198, 1979. Cryptologic Technician M 3 & 2, NAVEDTRA 10232-C, 1978. Radioman 3 & 2, NAVEDTRA 10228-G, 1978. Howeth, L. S., History of Communications-Electronics in the United States Navy, Bureau of Ships and Of fice of Naval History, Washington, D.C., 1963.

Chapter Two

Electronics Technician 3 & 2, Vol. 3, NAVEDTRA 10198, 1979. Cryptologic Technician M 3 & 2, NAVEDTRA 10232-C, 1978. Radioman 3 & 2, NAVEDTRA 10228-G, 1978. Cryptologic Collection Equipments, NAVEDTRA 10251, 1977. Basic Electronics, Vol. 1, NAVPERS 10087-C, 1970. Basic Electronics, Vol. 2, NAVPERS 10087-C1, 1979. Fundamentals of Single Sideband, NAVELEX 0967-LP-222-2010, 1958.

Chapter Three

Shipboard Electronics Material Officer, NAVEDTRA 10478-A, 1982. Electronics Technician 3 & 2, Vol. 3, NAVEDTRA 10198, 1979. Cryptologic Technician M 3 & 2, NAVEDTRA 10232-C, 1978. The Electronics Material Officer’s Guide to Shipboard Electromagnetic Interference Control,

Navseasyscom Std-407-5287556, 1983.

AII-2

Chapter Four

Shipboard Electronics Material Officer, NAVEDTRA 10478-A, 1982. Electronics Technician 3 & 2, Vol. 3, NAVEDTRA 10198, 1979. Cryptologic Technician M 3 & 2, NAVEDTRA 10232-C, 1978. Radioman 3 & 2, NAVEDTRA 10228-G, 1978. Satellite Communications Systems, United States Air Force, KEO-90008, 1972. Fleet Satellite Communications System Description, Naval Ocean Systems Center, January 1978.

Chapter Five

Shipboard Electronics Material Officer, NAVEDTRA 10478-A, 1982. Electronics Technician 3 & 2, Vol. 3, NAVEDTRA 10198, 1979. Microwave and Tropo-Scatter Communications Systems, NAVELEX 0101,112, 1972. Vlf, Lf and Mf Communications Systems, NAVELEX 0101,113, 1972. Design Handbook for Optical Fiber Systems, U.S. Army Communications-Electronics, CCC-CED-XES-78-0l, 1978. Cooper, Robert S., "SPACE Another Dimension of Defense," Defense 84, August 1984, pp. 12-19. McGraw-Hill, Vol. 3, Encyclopedia of Science and Technology, 1971.

McGraw-Hill, Vol. 12, Encyclopedia of Science and Technology, 1971. INDEX-1

Module 17 Index

A Amplitude modulation (AM) receiver, 2-11 Amplitude modulated transmitter, 2-3 to 2-4 Angle of inclination, 4-4 Antenna coupler group, 3-7 to 3-8 Antenna distribution systems, 3-11 to 3-15 Apogee, 4-3 Assembly, 1-8 Audio frequency tone shift (afts), 3-21 to 3-22, 3-29 Audio reproduction devices, 2-30 to 2-32 Audio tone, 2-25 to 2-26 Automatic digital network (AUTODIN), 1-17 Automatic frequency control (afc), 2-27 to 2-29 Automatic secure voice communications (AUTOSEVOCOM), 1-17 Automatic tracking, 4-14 Automatic voice network (AUTOVON), 1-17 B Balanced-phase detector, 2-28 Basic principles, teletypewriter and facsimile equipment, 3-15 to 3-19 Basic systems, teletypewriter and facsimile equipment, 3-14 to 3-34 Beat frequency oscillator (bfo), 2-23 Broadcast, 1-16 C Carrier reinsertion, 2-16 Communications satellite system, description of, 4-3 to 4-4 Communications applications, lasers, 5-18 Communications fundamentals, 1-15 to 1-18 Communications links, 1-15 to 1-16 Communications theory, introduction to, 2-1 to 2-37 Continuous wave transmitter, 2-2 to 2-3 Cryptographic equipment, 3-26 Crystal filters, 2-26 D Defense Communications Satellite Program (DCSP), 4-2 Defense Satellite Communications System (DSCS) phase II, 4-2 Defense special security communications system (DSSCS), 1-18 Delayed automatic gain control (dagc), 2-22 Detection, 2-12 Dummy load, 5-3 E Earth terminal characteristics, 4-9 Electrical telecommunications, 1-2 to 1-4 facsimile, 1-3 radiotelegraph, 1-2 radiotelephone, 1-2 teletypewriter, 1-3 Electromagnetic compatibility, 3-38 Electromagnetic interference, 3-38 to 3-39 Electromagnetic radiation, 3-40 to 3-43 Emergency equipment, 5-14 to 5-15 Equatorial orbit, 4-5 Equipment purposes, 3-1 to 3-15 Extremely low frequency (elf), 1-11 F Facsimile (fax), 1-3, 3-35 to 3-36 Fiber optics, 5-18 Fidelity, 2-11 Fleet broadcasts, 1-14 Forward agc, 2-21 Frequency modulated (fin) receiver, 2-12 to 2-14 Frequency multiplication, 2-6 Frequency synthesis, 2-29 Full Duplex, 1-16 Fundamental satellite communications system, 4-2 to 4-15 INDEX-2 Fundamental systems equipment, 3-1 to 3-47 equipment purposes, 3-1 to 3-15 antenna distribution systems, 3-11 to 3-15 handset, 3-2 radio set control unit, 3-2 to 3-3 receivers, 3-10 transfer switchboards, 3-3 to 3-4 transmitters, 3-4 to 3-10 security, quality monitoring, and safety, 3-36 to 3-43 electromagnetic radiation, 3-40 to 3-43 shipboard communications systems quality monitoring (QMCS), 3-38 to 3-43

Tempest, 3-36

transmission security, 3-37 summary, 3-43 to 3-47 teletypewriter and facsimile equipment, 3-15 to 3-34 basic principles, 3-15 to 3-19 basic systems, 3-14 to 3-34 Future satellite communications, 4-17 to 4-19 G Glossary, AI-1 to AI-6 Ground-to-air, 1-14 Group, 1-7 H Half duplex, 1-15 Handset, 3-2 Harmonics, 2-5 Helix, 5-3 to 5-4 Heterodyning, 2-12 High command communications network (HICOM), 1-18 High frequency (hf), 1-13 History of satellite communications, 4-1 to 4-2 I Image signals, 2-14 Inclined orbit, 4-4 Introduction to communications theory, 2-1 to 2-37 introduction, 2-1 receiver fundamentals, 2-9 to 2-30 audio reproduction devices, 2-30 to 2-32 frequency synthesis, 2-29 receiver characteristics, 2-10 receiver control circuits, 2-16 to 2-29 single-sideband, 2-14 to 2-16 superheterodyne receiver, 2-11 to 2-16 summary, 2-32 to 2-37 transmitter fundamentals, 2-3 to 2-9 amplitude modulated transmitter, 2-3 to 2-4 continuous wave transmitter, 2-2 to 2-3 frequency modulated transmitter, 2-4 to 2-5 single-sideband transmitter, 2-7 to 2-9 Introduction to miscellaneous communications systems and equipment, 5-1 to 5-20 introduction, 5-1 lasers, 5-17 to 5-18 communications applications, 5-18 theory of operation, 5-17 portable equipment, 5-13 to 5-17 emergency equipment, 5-14 to 5-15 operational equipment, 5-15 to 5-17 summary, 5-19 to 5-20 systems, 5-1 to 5-13 medium frequency and below, 5-2 to 5-8 microwave, 5-8 to 5-10 naval tactical data system, 5-10 to 5-13 Introduction to radio-frequency communications, 1-1 to 1-20 communications fundamentals, 1-15 to 1-18 communications links, 1-15 to 1-16 Navy-only networks, 1-18 switched networks, 1-16 to 1-18 introduction to naval telecommunications, 1-1 to 1-15