Lectrosonics UCR110 - Manual (Page 3)

Compact Receiver
GENERAL TECHNICAL DESCRIPTION
The UCR110 Receiver is comprised of a number of functional subsystems as shown in Fig 1, Block Diagram,
Fig 2, Control Panel and Fig 3, Side Panel
GENERAL FEATURES
The multi-frequency UCR110 FM Receiver is designed to operate with the Lectrosonics UM110 Transmitter and
features microprocessor control of 256 frequencies of operation within each frequency block. Each block covers 25.5
MHz with 0.1 MHz frequency spacing. Up to 256 special frequencies and 0.025MHz spacing can be programmed into
a unit by the factory or by authorized service centers. Any one of thirteen different frequency blocks numbered 21
through 33 are factory available from 537.6 MHz to 865.0 MHz.
The receiver’s unique microcontroller design provides simple operation for audio level/limit LED monitoring, RF level
LED monitoring, squelch, easy on-the-fly frequency programming and low battery warning. The UCR110 Receiver uses
20 kHz FM deviation for efficient use of the bandwidth and dual band companding for clean quiet audio. The receiver
operates on one 9 Volt alkaline battery for up to 8 hours and features a blinking LED low battery indicator. The voltages
are internally regulated for stability. The receiver is housed in a compact, rugged, lightweight aluminum enclosure. The
unit features a durable integral swing-aside battery compartment door.
DUAL BAND COMPANDOR
Traditionally, compandors have been a source of distortion in wireless microphone systems. The basic problem with
conventional systems is that the attack and decay times are always a compromise. If the time constants are fast, high
frequency transients will not be distorted, but this will cause low frequency distortion. If the time constants are slower,
low frequency audio distortion will be low, but high frequency transients will then be distorted.
The 110 system introduces the proven Lectrosonics approach to solving this basic problem, called “dual-band
companding.”
There are actually two separate compandors in the 110 system, one for high frequencies and one for low frequencies.
A crossover network separates the frequency bands at 1kHz with a 6dB per octave slope, followed by separate high
and low frequency compandors. The attack and release times in the high frequency compandor are fast enough to keep
high frequency transient distortion at a low level, and the low frequency compandor uses slower time constants,
reducing low frequency distortion to well below that of a conventional compandor.
PRE-EMPHASIS/DE-EMPHASIS
The signal to noise ratio of the 110 system is extended by utilizing pre-emphasis (HF boost) in the transmitter and de-
emphasis (HF roll off) in the receiver. Pre-emphasis and de-emphasis in an FM radio system usually provides about a
10dB improvement in the signal to noise ratio of the system, but the high frequency boost in the transmitter must be
removed in a purely complementary manner or else the frequency response of the original audio signal will be altered.
The dual-band compandor in the 110 Series system essentially provides a dynamic pre-emphasis/de-emphasis
function with low distortion.
Memory
Controller Control
Panel LED's
Low Freq
Compandor
Audio
Filter
IF Amp/FM
Detector
5V
Regulator
9V
Battery
On/Off
Mixer
Disc
RSSI
RF
Filter
RF
Amplifier
Frequency Synthesizer
S
T
R
Output
Jack
Audio Level
Control
Hi Freq
Compandor
Figure 1 - UCR110 Block Diagram
Rio Rancho, NM – USA 3