Lectrosonics UM450 User Manual download pdf (Page 4)

UM450

General Technical Description

Introduction

The UM450 transmitter combines a full 250 mW of

RF output with +/- 75 kHz wide deviation for extended

operating range and extremely high signal to noise ratio.

These key design features are coupled with the com-

pandor-free Digital Hybrid Wireless

audio chain and

packaged in the widely recognized Lectrosonics stan-

dard transmitter housing.

The unit is powered by a single 9V battery in the inter-

nal compartment, or from external DC using the sup-

plied ISO9VOLT battery eliminator. Rechargeable 9 V

batteries and charger are also included with the unit.

Digital Hybrid Technology

All wireless links suffer from channel noise to some de-

gree, and all wireless microphone systems seek to mini-

mize the impact of that noise on the desired signal. Con-

ventional analog systems use compandors for enhanced

dynamic range, at the cost of subtle artifacts (known as

“pumping” and “breathing”). Wholly digital systems defeat

the noise by sending the audio information in digital form,

at the cost of some combination of power, bandwidth and

resistance to interference.US Patent 7,225,135

Lectrosonics Digital Hybrid Wireless™ systems over-

come channel noise in a dramatically new way, digitally

encoding the audio in the transmitter and decoding it

UM450 Block Diagram

in the receiver, yet still sending the encoded informa-

tion via an analog FM wireless link. This proprietary

algorithm is not a digital implementation of an analog

compandor but a technique that can be accomplished

only in the digital domain, even though the inputs and

outputs are analog.

Channel noise still impacts received signal quality and

will eventually overwhelm a receiver. Digital Hybrid

Wireless™ simply encodes the signal to use a noisy

channel as efﬁciently and robustly as possible, yield-

ing audio performance that rivals that of wholly digital

systems, without the power and bandwidth problems

inherent in digital transmission.

Because it uses an analog FM link, Digital Hybrid Wire-

less™ enjoys all the beneﬁts of conventional FM wire-

less systems, such as excellent range, efﬁcient use of

RF spectrum, and resistance to interference. However,

unlike conventional FM systems, it does away with the

analog compandor and its artifacts.

No Pre-Emphasis/De-Emphasis

The Digital Hybrid Wireless™ design results in a signal-to-

noise ratio high enough to preclude the need for conven-

tional pre-emphasis (HF boost) in the transmitter and de-

emphasis (HF roll off) in the receiver. This eliminates the

potential for extreme distortion on signals with abundant

high-frequency information.

LECTROSONICS, INC.

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