18WuD2x

686 time modulation • tolerance
time modulation Any form of modulation in which
the instantaneous characteristics of a signal are
varied.
timeout The expiration of an allotted time period
for a given operation.
timer 1. A device for automatically controlling the
duration of an operation. See ELECTRONIC
TIMER. 2. A device for measuring the duration of
an operation.
time sharing In computer operations, a method
for interlaced (i.e., nearly simultaneous) use of a
machine or facility by two or more persons or
agencies. As the cost of computers diminishes, so
does the need for time sharing. Also see TIME-
DIVISION MULTIPLEXING.
time-sharing dynamic allocator In computer storage,
a program that allocates memory areas and
peripherals to programs being entered into a timesharing
system; it also controls program execution.
timeshift 1. To receive a message at a significantly
later time than when it was sent. 2. To use a
videocassette or videodisc recorder to view a television
program at a later time than when it was
transmitted.
time-shifting communications Any form of communications
in which the recipient reads or views
the message(s) at a significantly later time than
the message is sent from the source. A common
example is electronic mail (e-mail) using online
computer networks.
time signals Special radio transmissions made
under the auspices of the National Bureau of
Standards, for indicating Coordinated Universal
Time (UTC).
time slot A specifically defined time interval in a
data signal. It is of importance primarily in digital
communications, where a given time interval can
be high or low or at some discrete value.
time-space-time switch A large switch consisting
of a space block between two time blocks.
time zone One of the 24 zones into which the global
map is divided for the purpose of standardizing
time. Within these zones, mean solar time is determined
in terms of distance east or west of the zero
meridian at Greenwich (near London, England).
Each zone is equal to 15 degrees of longitude, or
1 hour. Four zones fall within the continental
United States: Eastern Standard Time (zone of the
75th meridian), Central Standard Time (zone of
the 90th meridian), Mountain Standard Time
(zone of the 105th meridian), and Pacific Standard
Time (zone of the 120th meridian). Also see
MERIDIAN, ZERO MERIDIAN, and ZONE TIME.
timing extraction The retrieval of a timing signal
from incoming data.
timing pin current Measured in microamperes.
The current that generates a timing waveform in
an integrated-circuit voltage regulator.
timing signal A repeating signal sent along with
data to control the synchronization of transmitter
and receiver.
tin 1. Symbol, Sn. A metallic element. Atomic
number, 50. Atomic weight, 118.71. Tin is widely
used in electronics as a structural material, a
constituent of solder, and (in foil form) as the
plates of some fixed capacitors. 2. To prepare the
tip of a soldering gun or iron, or the stripped end
of a wire or cable, by applying a coat of solder.
tin-oxide resistor See METAL-OXIDE RESISTOR.
tinsel Metal film strips interwoven with fabric
threads to provide a flexible cord, particularly for
headphones.
tint control In a color-television receiver, the control
for changing color hue.
tip jack The mating connector for a tip plug.
tip plug 1. A prod terminating in a phone tip. 2. A
plug-type connector terminating in a phone tip.
tip plug, 2
titanium Symbol, Ti. A metallic element. Atomic
number, 22. Atomic weight, 47.88. Titanium enters
into some dielectric compounds (e.g., titanium
dioxide).
titanium dioxide Formula, TiO 2 . A ceramic dielectric
material. Dielectric constant, 90 to 170.
Dielectric strength, 100 to 210 V/mil.
T junction See TEE JUNCTION.
Tl Symbol for THALLIUM.
T 2 L Abbreviation of TRANSISTOR-TRANSISTOR
LOGIC. (Also, TTL.)
TLA Abbreviation of TABLE LOOK-AT.
TLC Abbreviation of thin-layer chromatography.
TLU Abbreviation of TABLE LOOK-UP.
TM 1. Abbreviation of TRANSVERSE MAGNETIC.
2. Abbreviation of technical manual.
Tm Symbol for THULIUM.
TM mode See TRANSVERSE MAGNETIC MODE.
TM wave See TRANSVERSE MAGNETIC MODE.
T network See TEE NETWORK.
TNS Abbreviation of TRANSCUTANEOUS NERVE
STIMULATOR.
toggle A bistable device.
toggle switch A switch having a mechanism that
snaps into the on or off position at the opposite
extremes to which a lever is moved.
tolerance The amount by which error is allowed in
a value, rating, dimension, etc. It is usually