S-Z

S

Scanner: A radio receiver which automatically tunes through a sequence of user-selected frequencies.

Scatter: Propagation via random "scattering" of a signal directly off the ionosphere overheard; scatter signals are usually weak.

Search: A feature in certain receivers that will scan a frequency range at certain increments (such as 1 or 5 kHz) and pause on any frequency where a signal is present.

Selectivity: How well a receiver can reject signals on frequencies adjacent to the one you want to tune. It is indicated by a number of decibels rejection at a frequency point away from the desired signal.

Sensitivity: How well a receiver responds to weak signals, measure in microvolts; the lower the number of microvolts indicated, the more sensitive the receiver.

Shack: The room or other location where a radio station is operated from.

Shape factor: A receiver's selectivity measured at the 6 and 60 decibel rejection points. 

SHF: Abbreviation for super high frequencies.

Short skip: Propagation via the ionosphere over a distance of a few hundred miles or less.

Shortwave: Frequencies in the high frequencies' region of 3 to 30 MHz, but this term is often used to refer to frequencies from 1.7 to 30 MHz. 

Sideband: A signal equal to the bandwidth of the modulation frequency found above and below the carrier frequency in an AM signal.

Sidewinder: Slang for a SSB station.

Simplex: To transmit and receive on the same frequency.

Single sideband: A modulation technique that suppresses one sideband and the carrier and transmits only the remaining sideband.

SINPO: A code used in reception reports to rate the signal strength, interference, propagation conditions, atmospheric noise, and overall quality of reception on a scale from 1(lowest) to 5 (highest).

Skip: Any type of sky wave propagation via ionospheric refraction.

Skip zone: An area where a station being propagated via skywave cannot be heard because it is "skipping" off the ionosphere overhead.

Skyhook: Slang for an antenna.

Sky wave: Radio signals propagated by refraction in the ionosphere.

S-meter: A meter or bar graph that indicates the relative strength of a received signal.

Solid state: A circuit that uses no vacuum tubes---only transistors, integrated circuits, etc.

Space frequency: In FSK, the lower of the two frequencies used.

Speech processing: A circuit that increases the average 

Split channel: A frequency located between standard frequency allocations, such as the 10 kHz spacing of AM broadcast band frequencies or coordinated repeater frequencies.

Sporadic-E: Random patches of intense ionization that form in the E-layer of the ionosphere and refract higher frequency signals that normally cannot be refracted by the ionosphere.

Spread spectrum: A modulation method that spreads transmitter energy across a relatively wide frequency range according to a modulating code. 

Spurs: Undesired signals and frequencies in the output of a transmitter.

Squelch: A circuit in a radio receiver that quiets the receiver until the strength of a received signal exceeds a specified level.

Squelch tail: A brief bit of noise heard between the end of a radio transmission and the reactivation of the receiver's squelch circuit.

SSB: Abbreviation for single sideband.

Standing wave ratio: The ratio of power sent doan a feedline from the transmitter to the power reflected back through the feedline to the transmitter. A ratio of 1:1 is ideal; anything higher than 2:1 usually indicates a problem in the feedline or antenna.

Store and forward: A system for the receipt, storage, and later retransmission of packet radio messages.

Super high frequencies: The frequency range above 3000 MHz.

Surface wave: Another term for a ground wave.

SWL: Abbreviation for "shortwave listener."

SWLing: Abbreviation for "shortwave listening."

SWR: Abbreviation for standing wave ratio.

Synchronous detection: Similar to exalted carrier reception, but the replacement carrier tuning and tracking is done automatically by the receiver.

T

Telemetry: One-way radio transmissions used for tracking and measurement data.

Terminal node controller: A device used to convert digital signals from a PC into an analog form that can be transmitted by radio and to convert received analog signals into digital form for display on the PC's monitor.

Ticket: The license or other operating credential for a radio station and its operator(s).

Time-out: To transmit too long in a single transmission, causing a repeater's timer circuit to stop further transmissions.

TNC: Abbreviation for terminal node controller.

Tone access: A method of activating a repeater station that requires transmission of a brief tone before all transmissions to be relayed.

Top loading: Placing a loading coil at the top of an antenna in order to lower the antenna's resonant frequency.

Traffic: Messages to and from third parties exchanged by radio stations.

Transceiver: A combined transmitter and receiver sharing a common housing and many of the same components.

Translator: A device that receives multiple signals within a certain frequency range and simultaneously retransmits them in another frequency range.

Transponder: A device that will emit a radio signal when it receives a radio signal on a certain frequency.

Transverter: A device that takes one signal in a specified frequency range and simultaneously retransmits it in another frequency range. (This differs from a translator, which can handle more than one signal.)

Trap dipole: A dipole antenna with several coils, or "traps," that allow the antenna to be used on several bands.

Tropo: Term referring to tropospheric ducting.

Tropospheric ducting: Propagation of signals above 30 MHz via bending and ducting along weather fronts in the lowest layer of the Earth's atmosphere, the troposphere.

Trunking: A method of switching incoming signals between different repeater stations to prevent interference and ensure access to a repeater.

Turboscan: A very high scanning rate in a scanner receiver; also called hyperscan.

U

UHF: Abbreviation for ultra-high frequencies.

UHF low: The frequency range from 450 to 470 MHz.

UHF-T: The frequency range from 470 to 512 MHz. 

Ultra-high frequencies: The frequency range from 300 to 3000 MHz.

Unattended operation: Operation of a radio station without a human operator at the control point.

Uncoordinated repeater: A repeater station operating on frequencies not approved by the appropriate frequency coordinator.

Unity gain: An antenna that gives no gain or loss; its effective radiated power is equal to the transmitter power applied to it.

Upper sideband: The sideband higher in frequency than the transmitter's carrier.

USB: Abbreviation for upper sideband.

UTC: Abbreviation for coordinated universal time.

V

V: This is used after a frequency to indicate that it varies slightly.

Variable frequency oscillator: A circuit used to set the frequency of a receiver or transmitter.

VEC: Abbreviation for "volunteer exam coordinator," a group of hams who give license exams to prospective hams under authorization from the FCC.

Vertical polarization: An antenna that radiates, or receives best, radio waves having their electric field perpendicular to the Earth's surface.

Very high frequencies: The frequency range from 30 to 300 MHz. 

VFO: Abbreviation for variable frequency oscillator.

VHF: Abbreviation for very high frequencies.

VHF high band: The frequency range from 150 to 175 MHz.

VHF low band: The frequency range from 30 to 50 MHz.

VOX: A circuit that can turn a transmitter on and off automatically whenever someone speaks into the microphone.

W

Wallpaper: QSL cards, certificates, and other items decorating the walls of a radio station.

WAS: Abbreviation for "Worked All States," an award given by the ARRL to hams who contact other hams in all 50 states.

Wavelength: The distance between the same points on two consecutive radio waves.

WAZ: Abbreviation for "Worked All Zones," an award given by CQ Magazine to hams who contact other hams in 40 different geographic zones dividing up the globe.

Window: A frequency range set aside for foreign ham radio stations to transmit in while ham stations in the United States and Canada do not; American and Canadian stations call foreign stations on frequencies outside the window.

Work: To communicate with another radio station or stations.

Working frequency: A frequency that two or more stations can use to communicate with each other.

X

XYL: Radiotelegraph code for "ex-young lady," used to refer to the wife of a radio operator. 

Y

Yagi: A directional antenna consisting of a dipole connected to the receiver or transmitter and two additional elements, a slightly longer reflector and a slightly shorter director. Electromagnetic coupling between the elements focuses maximum power (or reception) in the direction of the director.

YL: Radiotelegraph abbreviation for "young lady," used to refer to a female radio operator or announcer.

Z

Zero beat: When the frequencies of two carriers are identical and there is no heterodyne heard between them.