Specifications

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GLOSSARY
reflected, i.e., bounce off the obstacle's surface
at an angle equal to the angle of incidence.
Remote Antenna
Antenna that is connected by a special anten-
na cable to the antenna input socket on a
receiver rather than directly to the antenna
input socket.
Room Radius
In a room within which a sound is generated, e.g.
by a loudspeaker, every point is characterized by
its own unique ratio of direct sound and sound
reflected from the walls. The distance from the
sound source at which the direct and reflected
sound energies are equal is called the “room
radius”. Outside the room radius the overall
sound pressure level is constant throughout the
room in the form of a “diffuse sound field”.
Sensitivity
A microphone's output voltage at any given
sound pressure level. A more sensitive micro-
phone will sound louder at the same gain set-
ting (the feedback risk being proportionately
higher). High sensitivity (condenser micro-
phones) is needed to drive the mixer adequate-
ly when far miking quiet sound sources.
Sensitivity is commonly given in mV/Pa or dBV
(referenced to 1 V/Pa) and measured at 1 kHz.
Here are some examples:
D 58 0.7 mV/Pa (-63 dBV)
D 190 1.6 mV/Pa (-56 dBV)
C 1000 S 6.0 mV/Pa (-44 dBV)
C 535 7.0 mV/Pa (-43 dBV)
C 480 B comb ULS/61 20.0 mV/Pa (-34 dBV)
C 562 BL 20.0 mV/Pa (-34 dBV)
Shadow loss
Signal loss which occurs in wireless transmission
if an obstacle blocks the line-of-sight transmis-
sion path between transmitter and receiver.
Signal Loss
Signal loss in a cable may be due to ohmic
resistance, dielectric leakage or radiation loss.
Signal-to-noise (S/N) Ratio
The S/N ratio is the difference between the ref-
erence sound pressure level of 94 dB (1 Pa
sound pressure) and the equivalent noise level.
Contrary to the equivalent noise level, a lower
S/N ratio means higher noise and therefore a
narrower dynamic range.
Squelch
Electronic circuit that switches the receiver off
when the received signal is too weak so the
associated extraneous noise and the self-noise
resulting from the receiver being switched off
will be inaudible. The squelch threshold is usu-
ally user adjustable within a preset range.
Tone coded squelch, tone-code squelch, tone
squelch
These terms denote a circuit that will open the
audio path only when it detects a system spe-
cific tone within the demodulated signal. This
tone is higher than 20 kHz, the upper end of the
range of human hearing, and is added to the
audio signal by the transmitter.
Total Harmonic Distortion (T.H.D.)
A measure of the non-linear distortion of a sig-
nal (e.g. a sine wave) that occurs when a
microphone or input is overloaded producing
harmonics (overtones) at multiples of the fun-
damental frequency.
Transient
Temporary change in voltage or current occur-
ring as a voltage or current source is switched
on or off, e.g., a transistor controlled by a pulse
signal.
Transient Response
The ability of a microphone to follow sudden
sound events immediately. Transient response
depends on diaphragm mass, transducer
damping factor, etc.
Types of Microphones
Microphones utilize different electroacoustical
principles to convert sound energy to electrical
energy:
1. Carbon Microphone A microphone using a
flexible diaphragm which moves in
response to sound waves and applies a
varying pressure to a container filled with
carbon granules, causing the resistance of
the microphone to vary correspondingly
2. Piezoelectric microphone A microphone in
which deformation of a piezoelectric bar by
the action of sound waves generates an
output voltage between the faces of the bar.
Also known as “crystal microphone”.
3. Magnetic microphone A microphone
employing a diaphragm acted upon by
sound waves and connected to an armature
which varies the reluctance in a magnetic
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