Lectrosonics HH/E01, Инструкция по эксплуатации

Страница: 4 / 16

HH/E01
LECTROSONICS, INC.
4
General Technical Description
Introduction
The HH/E01 handheld transmitter uses state-of-
the-art Digital Hybrid Wireless ® wireless technology,
selectable output power and a versatile microphone
capsule mounting system to meet the needs of audio
professionals and vocalists.
The compandor-free Digital Hybrid audio chain
preserves the quality of the selected microphone
capsule and delivers it to the sound and recording
system without coloration. This superb audio perfor-
mance and highly reliable RF transmission makes it
ideally suited for high end stage and studio produc-
tion.
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 Lectroson-
ics IFB receivers in special compatibility modes.
Digital Hybrid 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 compan-
dors to increase the signal to noise ratio, at the cost
of distortion artifacts. Wholly digital systems defeat
the noise by sending the audio information in digi-
tal form, at the cost of some combination of power,
bandwidth or channel count.
The Lectrosonics Digital Hybrid Wireless
®
sys-
tem (also called simply Digital Hybrid) overcomes
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 imple-
mentation 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 Digital Hybrid
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 Digital Hybrid has
eliminated the analog compandor and its artifacts.
No Pre-Emphasis/De-Emphasis
The Digital Hybrid design results in a signal-to-noise
ratio high enough to preclude the need for conventional
pre-emphasis (HF boost) in the transmitter and de-
emphasis (HF roll off) in the receiver. This eliminates
the potential for distortion of signals with abundant
high-frequency information.
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
50
Ohms
Isolator
Filter
Amp
Encoded Audio
and Pilot Tone
Bicolor
Modulation
LEDs
Switching
Power
Supply
Digital Signal Processor
Phase Locked Loop
LCD