STEP-TRANSMISSION SYSTEMA data transmission system that operates on direct current. It consists
of a step transmitter (rotary switch) and a step motor interconnected to transmit data (information)
between remote locations .
STICKOFF VOLTAGEA low voltage used in multispeed synchrosystems to prevent false
STOPThe last unit of a teletypewriter signal. It is always a mark .
STRANDED CONDUCTORA conductor composed of a group of wires. The wires in a stranded
conductor are usually twisted together and not insulated from each other .
STRANDSFine metallic filaments twisted together to form a single wire .
STRATOSPHERELocated between the troposphere and the ionosphere; it has little effect on radio
STROBOSCOPEAn instrument that allows viewing of rotating or reciprocating objects by producing the
optical effect of a slowing down or stopping motion .
STUBShort section of a transmission line used to match the impedance of a transmission line to an
antenna. Can also be used to produce desired phase relationships between connected elements of an
antenna  .
SUBASSEMBLYConsists of two or more parts that form a portion of an assembly or a unit .
SUBHARMONICAn 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
SUBSTRATEMounting surface for integrated circuits. May be semiconductor or insulator material
depending on type of IC .
SUDDEN IONOSPHERIC DISTURBANCEAn irregular ionospheric disturbance that can totally blank
out hf radio communications .
SUMMING NETWORKA combination of two or more parallel resistors used in servosystems as an
error detector. The output of the network is the algebraic sum of the inputs .
SUPERHETERODYNE RECEIVERA type of receiver that uses a mixer to convert the RF echo to an
IF signal for amplification .
SUPERHIGH FREQUENCYThe band of frequencies from 3 gigahertz to 30 gigahertz .
SUPERSONIC(1) Speed greater than the speed of sound . (2) Ultrasonic.
SUPPORT SYSTEMFor a radar, a system that provides an auxiliary input, such as dry air, electrical
power, or liquid cooling .
SUPPRESSIONThe process of eliminating an undesired portion of a signal .
SURFACE WAVERadio waves that travel along the contours of the earth, thereby being highly
SWAMPING RESISTORA resistor used to increase or "broaden" the bandwidth of a circuit .