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A-weighting A standard compensation (weighting) curve sometimes
applied to
audio measurements to account for the ear's response to low-level sound.
Frequently
applied to measurements of the residual noise levels of wireless microphone
systems
and other electronic devices. ("A-weighted noise.")
Acoustic Phase Interference See Phase
Cancellation .
Active Circuit An electronic circuit which uses active devices
such as transistors or
integrated circuits for its operation and which requires a power source
for operation.
Active Device Devices such as transistors, integrated circuits
and vacuum tubes that
require an external power source in order to perform an intended purpose,
such as
amplification.
Active Splitter An electronic device that consists of an RF signal
splitter (power
divider) preceded by an RF amplifier that compensates for the RF loss of
the splitter.
Used to allow one antenna to feed several receivers.
Adapter Mount
Term used to describe gooseneck microphones with a 5/8"-27
threaded rotating collar which screws onto the 5/8"-27 threads of a mic
stand,
mounting stud, etc.
Adjacent Channel Rejection The ability of a radio receiver to reject
interference
from an undesired signal on another nearby channel frequency. In wireless,
unless the
frequency separation between the desired signal and the adjacent signal
is specified,
the term is generally not of any practical significance.
Alkaline Battery A type of battery often used in electronic equipment.
Offers
longer operating life than other types of readily-available batteries.
Anechoic Chamber An acoustic space without echo or reverberation.
Often used
for the acoustic testing of microphones and loudspeakers.
Attenuate To reduce the amount of energy contained in an electrical
or radio
frequency signal. Also, to reduce the intensity or level of sound waves.
Back to top.
Attenuator Pad - a switchable
or removable internal electrical resistor that reduces the
audio volltage from the mic capsule before it reaches the rest of
the internal electronics.
It is used when the acoustic level of target sound sources is very high,
and avoids overload
distortion within the mic.
Balanced Circuit
A signal-carrying circuit with two active electrical conductors of
equal impedance on which equal, but oppositely-phased signal components
may
exist. Usually both conductors are enclosed within an overall metallic
shield, which
does not carry the signal. Widely used to reduce the pickup of hum and
noise in
audio system cabling. Also referred to as a balanced line or balanced
output.
Band A range of frequencies, as defined by regulatory authorities
or by commonly
accepted usage.
Bar Graph A display device indicating a value, usually by
means of a row of LEDs or
LCD segments. One or more LEDs or LCD segments illuminate to display the
present value of the function being metered in relationship to the maximum
value.
Have replaced fragile and expensive mechanical meters for most purposes
in audio
equipment. See also VU Meter.
Beamwidth The angle in degrees over which a directive antenna will
provide a gain
within 3 dB of the value in the direction of maximum gain.
Bi-directional Operating primarily in two directions, 180 degrees
apart. See
Figure-8.
Bias Voltage A low DC voltage typically supplied by a body-pack
wireless
transmitter to power a condenser microphone. (Not the same as phantom power.)
BNC Connector A type of small "twist and lock" RF connector often
used with
coaxial cables and antennas in wireless systems.
Board See Console.
Booster See RF Line Amplifier.
Boundary Microphone
A type of microphone that detects sound pressure level
changes at a boundary of the acoustic space in order to reduce interference
between
direct and reflected sound.
Boundary effect - when a microphone is near a wall or floor, or
any large rigid surface,
it will receive reflected sound from that surface at a fairly high level,
but fractionally later
than the original sound source. Depending on the distance, this can
lead to apparent peaks
and dips in the microphones frequency response.
Breathing An audible change in the level of background noise with
varying audio
levels. Most often used to describe an undesirable characteristic of companding
systems. A faster, somewhat more noticeable form is called pumping.
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Cable Loss The
inherent loss of coaxial RF cables due to conductor resistances,
absorptive losses in the insulating material and signal leakage between
the braids of
the outer shield. This typically occurs when cables are too long
(usually over 200 feet
from studio mics), they begin to cause a loss of high frequencies, a phenomenon
called cable loss.
Capsule The portion of a microphone that converts acoustic energy
to electrical
energy -- the inner sub assembly of the mic diaphragm, coil, and magnet
(for dynamics),
or diaphragm and backing plate assembly (for condenser mics). In
general, the capsule
is considered to be the integral unit, though it may contain many individual
parts. Often
includes shock mounts, acoustic isolators, protective covers and electronic
circuitry in
addition to the basic transducer. Also called an element.
Cardioid Describes the pickup pattern of one type of directional
microphone, which
is roughly in the shape of a heart. Such microphones are several dB less
sensitive to
sound arriving from sources at angles 90 degrees or greater away from its
front.
Carrier A modulated RF signal; that is, one which is carrying audio
or other
information. Sometimes used in a general manner to refer to any RF signal.
Channel In wireless, a designated radio frequency available for
use by the
transmitter and receiver. In audio, the circuit path for a specific signal,
or a functional
unit that is designed to independently process a signal.
Clipping In audio equipment, severe distortion caused by a signal
whose peak level
exceeds the capabilities of the device processing the signal. Results in
the flattening of
the signal peaks as if they had been "clipped" off.
Coaxial Cable A cable designed to conduct RF, consisting of an inner
conductor, a
tubular outer conductor and an insulating material in between the inner
and outer
conductor. The outer conductor is usually a woven copper braid covered
by an
outer layer of protective plastic.
Companding or Compansion A technique used to reduce the effects
of noise
unavoidably introduced by signal losses, circuit limitations and interference
during
transmission of an audio signal. Companding is also used to increase the
effective
dynamic range of the audio signal without causing overmodulation or overdeviation
of
the transmitted RF signal. The signal to be transmitted is first dynamically
compressed to reduce its overall dynamic range by a factor of, as an example,
2:1
("2-to-1"). After the signal arrives at the reception point, it is dynamically
expanded
by a corresponding factor of 1:2, thereby restoring the original dynamic
range.
During the expansion process, transmission noise is reduced by a 2:1 factor
such that
noise that was, for example, 40 dB below maximum output will be reduced
to 80 dB
below maximum output.
Compressor A circuit to perform compression of an audio signal.
May be either a
variable or logarithmic (2:1) type.
Condenser Microphone A type of microphone in which the diaphragm
is one plate
of a capacitor (condenser) containing an electrical charge. An electrical
output signal
is generated by detecting the variations in the charge present in the capacitor
resulting
from movement of the diaphragm by sound waves or audio currents. Some are
called capacitor
microphones.
Console A larger audio mixer with several input and output channels.
Also known as
a board.
Counterpoise The second half of an antenna, which "balances" the
radiating element
to launch the RF wave. Although not always readily apparent, a counterpoise
always
exists and its suitability can greatly affect the efficiency of the antenna.
A ground
plane, as found on ground plane antennas, is one type of counterpoise,
as is the outer
case or circuit board of a receiver using an attached whip antenna.
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` DAT Digital
Audio Tape.
dBm Decibels referred to 1 milliwatt.
dBu Decibels referred to the voltage equivalent of 0 dBm into a
600 ohm load.
0 dBu = 0.775V = ‚2.2 dBV
dBV Decibels referred to 1 volt.
Decibel A ratio of two levels, based upon a logarithmic scale.
Often abbreviated as
dB.
De-emphasis In FM radio systems, the noise accompanying the received
audio
increases rapidly in the higher audio range. To offset this, at the transmitter
the audio
signal is pre-emphasized to raise the level of the higher audio frequencies
relative to
the lower audio frequencies. This allows the received audio to be de-emphasized,
yielding an overall flat audio frequency response, while greatly reducing
the effects of
the noise introduced by the transmission process.
Diaphragm The portion of a microphone which is mechanically moved
by incident
sound (sound waves), thereby allowing conversion of sound energy to electrical
energy.
Distance Factor (DF) Provides an indication of a directional microphone's
increased working distance, compared to a DF of "1.0" for an omnidirectional
mic.
Directivity or Directional The property of transmitting or
receiving energy more strongly in some
directions than in others. This includes any microphone that discriminates
in terms of response
for sounds coming from different angles. The greater or lesser degree
of directionality is indicated
by the microphones polar response.
Direct vs. reflected sound
microphones "hear" sound directly from the source, but also receive
sound that has bounced around the room, and which enters the mic
from all angles. Directional
mics tend to allow a higher proportion of direct sound by rejecting some
of the bounced sound.
Dynamic Microphone. A type of microphone consisting of a diaphragm
mechanically attached to a coil operating in a magnetic field. Sound pressure
variations cause movement of the coil within the magnetic field, producing
a small
voltage across the coil terminals.
Dynamic Range The range in dB between the noise floor of a device
and its
defined maximum output level. The term applies to both audio devices and
RF
equipment, but the maximum output level is defined differently.
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Electret Condenser
Microphone A type of condenser microphone whose
transducer contains an electret material that permanently retains an electrical
charge,
and does not require the external voltage source required by other types
of
condenser transducers to polarize the diaphragm. The charge is retained
by the use of
special plastic like materials used in constructing the capsule, and stays
constant for years
without recharging. Electrets do not need an external power supply
for polarizing voltage, but
still need a small DC voltage (usually from an internal battery) for the
active electronics.
Feedback
In acoustics, the undesirable leakage of audio from loudspeakers back
into a microphone, resulting in a loud squeal or howling sound, or in less
severe
cases, a hollow ringing sound quality or whistles.
FET Field-effect transistor, typically used as an impedance converter
at the element
in a condenser microphone.
Figure-8 or Figure-of-8 A bi-directional microphone pattern, with
two equal lobes
180 degrees apart. Also describes some antenna patterns, such as that of
a dipole.
Frequency Diversity Use of different frequencies simultaneously
for receiving,
selecting the one with a better signal. Primarily used for military and
large commercial
applications. Wireless microphones typically use space diversity (see True
Diversity).
Frequency Search A process of searching for wireless microphone
frequencies that
are free from interference caused by other frequencies in use at a particular
location,
and do not in turn interfere with the other used frequencies. Normally
performed
using a personal computer and a program designed for this purpose.
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Gain Before Feedback
The amount of total gain that can be achieved in an audio
system, from microphone to speakers, before the onset of acoustic feedback.
Ground Effect A loss of operating range, sometimes significant,
when wireless
antennas are positioned near to the ground. Caused by partial signal cancellations
due to RF energy reflected up from the ground mixing with the direct RF
signal.
Because of the shorter wavelengths involved, UHF frequencies usually are
less
affected than VHF frequencies.
Ground Lift Switch or Ground Lifter A switch to disconnect the
shield of a
balanced audio cable from the local equipment ground. In certain situations,
can
eliminate ground loop and hum problems.
Ground Loop A condition where the local grounds at each end of
a length of cable
are at a different AC potential. This sometimes causes hum and noise problems
and
may require the use of corrective measures such as a ground lift switch
on the
equipment.
Ground Loss See Ground Effect.
Harmonic
An exact integer multiple of a fundamental frequency or tone.
Harmonic Distortion Undesired signal harmonics at the output of
a device which
were not present at the input. See also T.H.D.
Headworn Microphone A miniature microphone mounted on a short boom
and
held in place near a performer's mouth by some type of headband or similar
device.
Useful for vocalists who need their hands free during dance numbers or
to play an
instrument.
Hi-Z (High impedance) A loosely-defined audio term used to describe
devices
whose input or output impedance is greater than approximately 5,000 ohms.
High-impedance mics typically are 20,000+ ohms.
HRS Connector (Hirose Connector) A type of audio connector often
used for the
microphone connections on wireless body-pack transmitters. The connector
wiring is
not standardized within the wireless industry.
Hum A continuous undesired audio component at the frequency of
the incoming AC
power line, or a harmonic.
Hypercardioid Describes the pickup pattern of one type of directional
microphone.
Its front lobe is somewhat narrower than that of the cardioid microphone,
and it
possesses a small rear lobe in which the sound pickup is out-of-phase with
that of
the front lobe.
Hz An abbreviation for Hertz, the number of cycles per second of
a signal.
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Image Rejection
The measure of a receiver's ability to reject signals at its image
frequency. Normally expressed as the ratio, in dB, of the receiver's sensitivity
at the
desired frequency versus the sensitivity at the image frequency.
Impedance The opposition to the flow of an AC signal offered by
a circuit or
device. See also RF Impedance, Hi-Z, Lo-Z.
In-line A term used to describe microphone accessories that are
connected between
the mic and the mixer input.
Instrument In audio, generally refers to a musical instrument of
some type.
Intermodulation A process whereby strong signals mix together in
an active circuit
to create undesired output frequencies that are not present at the input.
International Power Connector A type of internationally-approved
power
connector widely used for AC power input on audio equipment, allowing
international use by means of power cords specific to particular countries.
Also
referred to as an IEC connector.
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kHz Kilohertz,
1,000 Hertz, or one thousand cycles per second.
Lavalier Microphone
A type of miniature microphone that is usually worn fastened
to clothing somewhere near the user's mouth. Also referred to as a clip-on
or lapel
microphone. Can also be used in live sound to pick up the sound of
various acoustic instruments.
LCD Abbreviation for Liquid Crystal Display. A type of display,
usually numerical,
used in electronic equipment. Dark characters are formed on a lighter background.
Requires external back lighting to be visible under low-light conditions.
LED Abbreviation for Light Emitting Diode. A semiconductor device
that emits
visible light when conducting current. Has replaced incandescent lamps
as indicators
in most electronic equipment.
Line Level Audio signals whose maximum average levels can exceed
approximately
0.5 volts, or a circuit which can output or accept such signals.
Line Microphone See Shotgun Microphone .
Lo-Z (Low impedance) A loosely-defined audio term used to describe
devices
whose input or output impedance is less that approximately 5,000 ohms.
In
microphones, Lo-Z commonly is 50 - 1,000 ohms.
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MHz Megahertz,
one million Hertz, or one million cycles per second.
Mic Level Audio signals whose level is similar to those of microphones,
that is,
generally ranging from roughly 0.001 volts (1 mV) to 5 volts.
Mini-plug A miniature phone plug, available in both "mono" and
"stereo" versions.
The most common size for audio use is 3.5 mm.
Mini-XLR Connector
A Switchcraft® Tini-QG® connector, frequently called a
mini-XLR, is available in several configurations. Be careful, the pins
are numbered in
the opposite direction from an XLR! Often used on small boundary microphones,
and for the mic connections on some wireless body-pack transmitters. The
connectors' wiring schemes are not standardized within the microphone industry.
Mixer A device for summing two or more electrical signals. In general
audio usage,
a device to control and sum the outputs of two or more microphones. In
wireless
microphones, the receiver circuit which mixes the RF signal with the local
oscillator
signal to obtain the IF output.
M/S Stereo Microphone Mid-side or mono-stereo microphone. A type
of stereo
microphone with both a cardioid transducer facing forward and a "figure-8"
transducer which is mounted such that its maximum sensitivities are pointed
"sideways." An electronic circuit is required to develop the two stereo
channels from
the two transducer outputs. With this technique, it is possible to combine
the
transducer outputs in such a manner as to vary the stereo image.
MOSFET A type of RF transistor often used in wireless microphone
receivers.
Multi-pattern Microphone A type of microphone with a switch to
allow selection
between more than one polar pattern.
Mute To turn off or silence an audio signal. In wireless, sometimes
used to indicate
the squelched condition for a receiver.
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Neodymium
A rare metallic element that can be made into particularly strong
magnets. Superior to the magnetic materials more commonly used in dynamic
microphones.
NiCad A type of rechargeable battery often used in electronic equipment.
Typically
provides only a small fraction of the operating time of alkaline batteries.
Noise Reduction Any technique for reducing the amount of undesired
noise in an
audio signal. Companding is one of several such techniques.
Noise Squelch A squelch detection technique that monitors noise
at frequencies
above the audio range at the FM demodulator output. A high level of noise
in this
region indicates a weak or unusable RF signal, or some form of interference.
Back to top
Off-axis - an angle other than "on-axis" is called "off-axis".
Off-axis response - the frequency response of most microphones is somewhat
uneven
for sounds entering from any direction except straight on. Some microphones
maintain
very good frequency response at a fairly wide angle away from the on-axis
direction.
A microphone's off-axis performance can be visualized via its polar-response
graph.
Omnidirectional (Omni) Describes a device such as a microphone
or antenna that operates
equally well from any angle.
On-axis - looking straight into the center of the microphone's diaphragm.
Also defined as
"zero degrees" on the polar plot. Most microphones obtain their best
performance for sounds
entering on-axis.
Oscillator An electronic circuit that generates a specific tone
or frequency.
Overload A condition where the signal levels present exceed the
capabilities of a
device, causing an undesirable consequence called distortion.
This effect can be controlled
by using an attenuator pad.
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Pa See Pascal.
Pad An attenuator, typically used to reduce mic output to avoid
equipment input
overload.
Pascal (Pa) A unit of measure for sound pressure. One Pascal equals
94 dB SPL.
Passive Lacking any active devices or active circuitry.
PCB Abbreviation for Printed Circuit Board. An insulating material
with attached
electrical conductors, and usually, various types of electronic devices.
Phantom Power
a powering system for condenser microphones where DC voltage is
sent down the same wires that transmit the tiny audio currents to
the preamp or line-in at
the deck or console. Because the DC voltage is sent equally down
both audio
conductors (and forms a current flow only with the third "ground" conductor),
it effectively
cancels itself out at the console audio input, hence the term "phantom".
The advantage is
that an extra conductor is not needed to transfer power to the mic's electronics.
Phase ("In-phase/Out-of-phase") Actually refers to the polarity
of an electrical or
acoustic signal. If two or more signals or devices are "out-of-phase" with
respect to
each other, cancellation or other disturbance of the combined output can
result.
Some examples of operating phase (polarity) definitions: "Positive sound
pressure
causes positive output" (microphones) or "positive input causes positive
acoustic
output" (speakers).
Phase
Cancellation Undesirable dips and peaks in frequency response caused
by
mixing the outputs of two microphones which are picking up the same sound
but with
different arrival times. For example, this can occur when two microphones
are
placed near each other, but still with space between them; or when wireless
microphone users stand next to each other. Also referred to as acoustic
phase
interference. See also "3:1 Rule".
Phase Lock Loop The control mechanism used in most frequency synthesizers.
Operates by comparing the phase of a sample signal, usually the frequency-divided
output of the RF oscillator, with a precision fixed reference frequency.
The phase
comparator output then drives a control loop which forces the RF oscillator
frequency to be an exact multiple of the reference frequency. Changing
the frequency
divider ratio will lock the oscillator to a new frequency, changing the
operating
frequency of the synthesizer. See also Synthesizer.
Phasing Diversity A type of diversity where two antennas but only
one receiver
channel are used. The two antennas are electronically combined, which has
the effect
of creating a single virtual antenna whose electrical position is at some
point in space
other than the location of the two physical antennas. When the receiver
detects a
signal loss that might be due to a multipath dropout, it experimentally
changes the
electrical phase of one of the antennas. This has the effect of moving
the electrical
position of the virtual antenna in space. This action may correct the signal
loss, have
no effect, or make it worse, since the receiver cannot determine the actual
cause of
the signal loss or anticipate the effect of the phase change. The principal
advantage of
phasing diversity is low cost.
Phono Plug Connector A type of plug-in audio connector with a 1/4-inch
(6.3 mm)
diameter metal contact sleeve, and either one or two signal contacts. Widely
used in
the telephone industry, particularly in the past, hence the name.
Pilot Tone A specific tone frequency applied to a transmitter outside
the audio
range; used by tone coded squelch systems for receiver squelch control.
Plate Microphone See Boundary Microphone
.
PLL Abbreviation for Phase Lock Loop.
Polarized In condenser microphones, the source of the charge contained
in the
microphone capsule. Transducers may be of the internally polarized (electret)
type,
or may require an outside source of polarizing voltage (externally-polarized).
Polar Pattern A plot of a device's sensitivity or efficiency as
a function of the angle
around the device. Widely used to characterize the performance of microphones,
loudspeakers and antennas.
Polar response a term used to describe the performance of a microphone
over a full
range of pickup angles. The polar response is expressed using a "polar
plot," and there
will usually be several lines on the plot to indicate the varying polar
response to the microphone
over a range of test frequencies.
Pop An undesirable short duration microphone output, often caused
by explosive
exhalation of air during the formation of certain vocal sounds.
Pop Filter A material, usually some form of acoustically-transparent
foam and/or
mesh, used on or in microphones to reduce the effects of breath blasts
and air
currents.
Power Supply A source for the power needed for active electronic
circuitry. Can
consist of one or more batteries, or an electronic circuit which converts
AC line
voltage to the type of power required by a particular device.
Preamplifier A type of amplifier specifically designed to amplify
low-level signals.
Processor A device which modifies an electrical signal, usually
in a dynamic manner.
In wireless, sometimes used to refer to companding.
Propagation The radiation of signal energy through a physical area
or space.
Proximity Effect The exaggeration of low-frequency sounds in a
directional
microphone when it is very near the sound source. This can be counteracted
by engaging a rolloff filter.
Pumping Undesirable and objectionable gain or background noise
level changes in a
companding system. A slower, somewhat less noticeable form is called breathing.
Back to top
Quick Mount
Term used to describe gooseneck microphones with an integral
output connector which plugs into a matching jack.
Ratio Combining
A technique used in true diversity receivers whereby the audio
from the two receiver channels is mixed in varying ratios, depending upon
which
channel has the stronger signal. In the more common switching approach,
the
receiver simply selects the audio from the better channel by means of an
electronic
switch.
Remote Power See Phantom Power .
Rolloff Filter
- an internal electrical filter in the mic that can be switched in to lower
the
response at low frequencies. Some mics have a filter that allows
the user to select from
two different bass frequency points, for more precise action. The
rolloff filter is
generally used to counteract the proximity effect.
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Selectivity
The measure of a receiver's ability to reject interfering signals at
frequencies near the operating frequency.
Sensitivity In wired microphones, phono cartridges, etc., the amount of
output for a
given input. In RF receivers, the amount of input signal a device requires
in order to
produce a reference quality of output.
Shield - a metal covering or surrounding sheath that prevents external
electrical fields
from interfering with audio voltages in the microphone cabling.
Shock Mount In microphones, a mechanical device, usually incorporating
some
type of shock-absorbing elastic material, designed to acoustically isolate
the
transducer from shock, vibration and handling noise. Both internal and
external shock
mounts are commonly used.
Shotgun Microphone
A type of highly-directional microphone having a very narrow
elliptical pattern and extremely reduced pickup from the sides and rear.
Shotguns are
effective at picking up sounds at greater than normal working distances.
It has a very
narrow pickup angle and must be carefully "aimed" by the operator.
Signal-to-noise Ratio or SNR The ratio, normally expressed in dB,
between the
level of the desired signal and the level of unwanted noise.
Sound Pressure Fluctuations in air pressure due to the presence
of a sound. This
sound pressure is expressed in units such as Pascals, microbars, or dynes/cm2.
Sound Pressure Level or SPL A standard measurement of the amplitude
of sound,
expressed as the ratio in decibels between the measured sound pressure
and
standard reference of 0 dB SPL = 20 microPascals = 0.0002 dynes/cm2.
Space Diversity See True Diversity .
Squelch A receiver circuit designed to mute (squelch) the audio
output when the
received signal is too weak to provide acceptable audio or, in some cases,
when the
wrong signal is being received. See also Noise Squelch, Signal Level Squelch,
Tone
Coded Squelch.
Stereo Microphone A type of microphone with more than one internal
transducer
that is capable of generating a stereo output. See also M/S Stereo Microphone,
X/Y
Stereo Microphone.
Subcardioid Describes the pickup pattern of one type of directional
microphone,
which is only modestly directional but retains some degree of rejection
of sounds
arriving from the sides and rear. Provides a somewhat broader and less
well-defined
pattern than does a standard cardioid microphone.
Subcarrier A secondary tone or carrier which modulates a primary
carrier. The
subcarrier frequency is normally above the audio range, and may itself
be modulated
to transmit audio or other information.
Supercardioid or hypercardioid - directional microphone patterns
that favor sounds
entering on-axis, and reject off-axis sounds to a greater degree than the
cardioid pattern.
Suspension The mounting for a microphone capsule, generally designed
to provide
some degree of mechanical isolation between the capsule or transducer and
the
microphone body in order to reduce handling noise.
Switching Diversity The most common implementation of a true diversity
receiver,
in which the audio from the better of two receiver channels is continuously
selected
by means of an electronic switch. See True Diversity
.
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T.H.D. Abbreviation
for Total Harmonic Distortion . The sum total of all undesired
harmonic energy present in an output signal, usually expressed as a percentage
of the
total output signal.
Third Order Intermodulation One of several types of intermodulation
products
that can be created in electronic circuits. In this case, the second harmonic
of an
input frequency mixes with a second input frequency to yield a third output
frequency
which is not present at the input.
Thread Mount See Adapter Mount .
"3:1 Rule" ("3-to-1 Rule") Rule-of-thumb ratio for the minimum distance
mics
should be spaced apart ("3 times X"), compared to their distance from the
sound
source ("X"). See also Phase Cancellation
.
Tini-QG See Mini-XLR Connector .
Tone Coded Squelch A form of receiver squelch that relies upon
detection of a
specific tone at a frequency above the audio range. If the tone is present
at the FM
demodulator output, it is assumed that it originates with the tone oscillator
in the
wireless transmitter and that the correct signal is being received. Usually
combined
with another type of squelch such as signal level squelch.
Transducer In audio, a device to convert sound to electrical energy
or vice versa.
Microphones and loudspeakers are two type of transducers. Also refers to
the
portion of a microphone that is directly involved with conversion of sound
energy to
electrical energy. A phono cartridge also is a transducer, one that converts
mechanical energy (vibration of the stylus) into electrical energy.
Transformerless An electronic circuit capable of outputting or
receiving a balanced
audio signal without the use of a magnetic transformer. Transformerless
circuits
generally have wider frequency response and lower distortion than circuits
using
transformers.
Tube microphone - a condenser microphone that uses a vacuum tube
as the internal
impedance translator element. Non-tube condenser microphones use
a type of transistor
called FET (field effect transistor) as an impedance translating element.
True Diversity
A form of diversity that uses two spaced antennas and two receiver
channels tuned to the same frequency. Essentially eliminates signal loss
(dropouts)
due to multipath by instantaneously selecting the audio output from the
receiver
channel having the stronger RF input signal. Also referred to as space
diversity or
dual-receiver diversity.
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Unbalanced
Refers to a signal-carrying circuit with one electrical conductor and an
overall metallic shield. Also referred to as an unbalanced line.
Unidirectional Describes a device which radiates or receives energy
more efficiently
from a single direction than from all other directions.
VU Meter Originally, an audio output meter for broadcast and recording
studio
consoles with precisely defined reference level and ballistic characteristics.
"VU
meter" has become the common name for any audio output metering, particularly
on
mixers and related equipment. See also Bargraph.
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Wall Power
Supply A type of power supply, or in some cases AC transformer, that
plugs into an AC outlet and provides low-voltage power to an electronic
device.
Wall Transformer A type of power transformer | 
