Lectrosonics HHa, Инструкция по эксплуатации

Страница: 4 / 20

HHa
LECTROSONICS, INC.
4
General Technical Description
Introduction
The HHa handheld transmitter uses state-of-the-art
Digital Hybrid Wireless
®
wireless technology, select-
able output power and a versatile microphone capsule
mounting system to meet the needs of audio profes-
sionals and vocalists.
The compandor-free Digital Hybrid audio chain pre-
serves the quality of the selected microphone capsule
and delivers it to the sound and recording system
without coloration. This superb audio performance and
highly reliable RF transmission makes it ideally suited
for high end stage and studio production.
Digital Signal Processor
The DSP encodes the digitized audio from the A-D
converter and adds an ultrasonic pilot tone to control
the receiver’s squelch in systems that use pilot tone. It
also controls the input limiter and audio metering.
Compatibility Modes
The transmitter was designed to operate with Lec-
trosonics Digital Hybrid Wireless
®
receivers and will
yield the best performance when doing so. Due to
the flexibility of digital signal processing, however, the
transmitter is also able to operate with Lectrosonics
200 Series, Lectrosonics 100 Series, IFB and certain
non-Lectrosonics analog receivers in special compat-
ibility modes. (Contact the Lectrosonics Sales Depart-
ment for a complete list of compatible receivers.)
Digital Hybrid Wireless
®
Technology
All wireless links suffer from channel noise to some
degree and all wireless microphone systems seek to
minimize the impact of that noise on the desired signal.
Conventional analog systems use compandors to
increase the signal to noise ratio, at the cost of distor-
tion artifacts. Wholly digital systems defeat the noise
by sending the audio information in digital form, at
the cost of some combination of power, bandwidth or
channel count.
The Lectrosonics Digital Hybrid Wireless
® system over-
comes channel noise by digitally encoding the audio
in the transmitter and decoding it in the receiver, yet
still sending the encoded information via an analog FM
wireless link. This proprietary algorithm is not a digital
implementation of an analog compandor. Instead, it
is a technique that can be accomplished only in the
digital domain, even though the inputs and outputs are
analog signals.
Because it uses an analog FM link, the system enjoys
all the benefits of conventional FM wireless systems,
such as excellent range, efficient use of RF spectrum,
and long battery life. However, unlike conventional FM
systems, the design has eliminated the analog com-
pandor and its artifacts.
Wide Deviation
±75 kHz deviation is used in the Digital Hybrid and 200
Series compatibility modes to dramatically improve
the capture ratio, signal to noise ratio and dynamic
range of the wireless system. This, in conjunction with
accurate input gain adjustment, produces outstanding
audio quality that rivals a hard wired connection.
Mic
capsule
Bias 5V
+7V
Input
Amp
Interface
Shunt
Limiter
MENU/SEL
BACK
MUTE
POWER
Reference
Crystal
Reference
Crystal
3 V
Battery
Variable
Switching
Power
Supply
Hi.Lo
Pass
Filter
Digital
Pot
Audio
Level
Phantom
Power
Audio
A-D
Converter
11001001
D-A
Converter
11001001
Control P
anel
Microprocessor
Voltage
Controlled
Oscillator
Final
Amplifier
Filter
Amp
Encoded Audio
and Pilot Tone
Bicolor
Modulation
LEDs
Switching
Power
Supply
Digital Signal Processor
Phase Locked Loop
LCD