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Com/Rad Inc. SCG - HF SSB Communications Equipment HF Communications Glossary 10-meters: 28.0-29.7MHz 15-meters: 21.0-21.450MHz 20-meters:: 14.0-14.350MHz 40-meters: 7MHz to 7.3MHz 80-meters: 3.5-4.0MHz 160-meters: 1.8-2.0MHz (+): positive (power supply input) (-): negative (power supply input) A3A: mode of single sideband with -16dB pilot carrier A3H: AME or AM compatible (carrier with only upper sideband) A3J: telephony; single sideband with suppressed carrier AGC: automatic gain control which prevents receiver overload ALC: automatic loading control which prevents transmitter overload AMP: amplifier AMTOR: amateur radio equivalent of SITOR with slightly different standards ATTN: attenuator which reduces a received signal ADSP: Adaptive Digital Signal Processing; exclusive to SGC, a DSP technology which processes the signal to eliminate unwanted noise and improve incoming signal AM: amplitude modulation, low efficiency type of radio transmission generally used for broadcast AM radio station bands with 100% carrier inserted AMVER: Coast Guard operated system for rescue "automated mutual assistance vessel rescue system" AM broadcast band: A band ranging from 530 to 1605 KHz. Amateur bands: HF frequencies of 1.8MHz to 29.7 MHz set aside for amateur radio operators. Amplitude: The height of a radio or sound waveloudness. Amplitude Modulation: Adding information to an RF carrier by increasing and decreasing amplitude. Analog: Representing data with physical quantities (a watch with hour and minute hands is an analog time display). ANTENNA: any part of any SSB system that radiates radio energy ARQ: automatic repeat request; a mode to compare transmission; a repeat signal is sent only when requested by the receiving station BAND: a range of frequencies, usually within a one MHz span BANK: a collection of channels to be scanned as a group in order Binary: A system of numbers represented only by digits 0 and 1. (Contrast with decimal which uses digits 0 through 9.) Capacitor: A device to store electrical energy. Carrier: An unmodulated RF signal. CHAN: channel CHASSIS GND: chassis or cabinet ground CLAR: clarifier; allows receiver frequency to be offset slightly from transmitter frequency COMM: communication; also used to reference serial communications computer port CW: continuous wave; to transmit the mode of Morse code CRYSTAL: a piece of quartz mineral that will resonate at a particular frequency and used as a reference in transceivers COAX: an electrical conductor which carries radio energy from a transmitter to an antenna system; the inner conductor is insulated from an external wire mesh shield Chip: A wafer of semiconductor material used in an electronic circuit. Copy: When radio operators hear and write down a message, they "copy." DATA I/O: data input/output DC: direct current DUPLEX: a method of frequency in which ship stations transmit on one frequency while shore stations transmit a different frequency DSP: digital signal processing; technology which eliminates unwanted noise to enhances a signal DXpedition: A contest in which amateur radio operators try to reach distant stations. EMER: emergency FEC: forward error correction; a mode to compare transmission; each character is sent twice and the redundancy of the code serves as the check FEEDLINE: the method of connecting the antenna to the radio FREQUENCY: the number of polarity alternations per second measured in Hertz. KHz = thousand Hertz; MHz = million Hertz FM: frequency modulation FWD: forward transmit power going to the antenna GAIN: the amount of amplification a system has; in antenna systems, the gain is the measurement of the directional characteristics GROUND: a connection to earth or an earth counterpoise GROUNDPLANE: an artificial ground used for antenna systems GROUNDWAVE: a radio signal that travels along the earth, bending over the horizon GMT: Greenwich Mean Time (universal time) the international standard time referred to the zero degree meridian Heterodyne: The frequency that results when two radio frequencies "beat" together (one frequency minus the second frequency = heterodyne). Hertz: See Hz. HF: A range of frequencies from 3 to 30 MHz. Hz (Hertz): A measure of frequency: one cycle per second Inductor: A coil onto which voltage is imposed by another coil. IMPEDANCE: the apparent opposition in an electrical circuit to the flow of an alternating current IONOSPHERE: electricity conducting layers in the earth's upper atmosphere KHz: 1000 Hertz LCD: liquid crystal display LPA: linear power amplifier LSB: lower sideband LED Light-emitting diode: a semiconductor that lights up; used in digital displays. MEMORY: a computer memory address to which channel information may be assigned MHz: 1 million Hertz MF: (Medium Frequency), a band of frequencies in the 2 MHz range used for short range communications Microprocessor: A computer processor contained on a chip. MODULATION: the process of varying the amplitude, frequency or phase of a carrier or signal OSCILLATOR: a device that produces alternating current Oscilloscope: A display of frequency on a cathode ray tube. PCB: printed circuit board Phase-shift: Removing an unwanted frequency (or sideband) by imposing a mirror-image frequency so the two cancel each other. PTT: push to talk PEP: peak envelope power; commonly a power output rating PROPAGATION: the characteristics of different radio frequency transmissions, generally in regard to usable distance in relation to frequency and time of day RF: radio frequency; any frequency higher than a person can hear RESONATE: the frequency that a circuit is tuned to RADIATE: the movement of energy away from a place, as in the radiation of an antenna SSB: Single Side Band; a high efficiency type of radio transmission generally used for long distance communications where energy is not radiated until modulation is present SQL: squelch SIMPLEX: a method of frequency use in which stations transit and receive on the same frequency SITOR: a commercial system of radio teletype for ship to shore, ship to ship and between ships and any telex subscriber; "ship international transmitting over radio" SKIP: the bounce of the radio signal off the ionosphere SKYWAVE: a radio signal which is projected into the ionosphere and bounces one or more times before returning to earth SYNTHESIZER: the device that produces and controls frequencies through synthetic results SNS: exclusive to SGC; spectral noise subtraction; works with DSP in signal processing to improve incoming signals TELEX: a commercial service involving teletypewriters connected through automatic exchange; "teleprinter + exchange" TRANSCEIVER: a term applied to equipment that both transmits and receives USB: upper sideband UTC: coordinated universal time; same as GMT VCO: voltage controlled oscillator VHF: Very High Frequency; commonly refers to a short range type of radio whose signal is transmitted on a line of sight from antenna to antenna VSWR :voltage standing wave ratio; a measurement of the efficiency of an antenna system; it measures the energy which is projected out and reflected back to the antenna VOLTAGE: a measurement of electrical pressure of the current times resistance VDC: voltage direct current WAVELENGTH: distance between two successive radio waves WORK: to be in radio contact or communication with another station XMT: transmit XFMR: transformer |
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