General technical description ucr195 receiver, Figure 1 - ucr195d block diagram – Lectrosonics UCR195D User Manual

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GENERAL TECHNICAL DESCRIPTION

UCR195 RECEIVER

The UCR195D is a high performance, dual-conversion,
UHF receiver. The RF performance is extremely stable
over a very wide temperature range, making the
UCR195D perfectly suited to the rough environmental
conditions found in the field. The proprietary audio
processing includes a dual-band compandor for very low
distortion and a superior signal to noise ratio. The
squelch system is operated by a separate pilot tone and
mutes the audio output directly at the output connector.
The audio output is calibrated for exact level matching,
with a ten LED bar graph meter.

DIVERSITY RECEPTION

The antenna phase switching diversity technique was
chosen in order to keep the receiver compact enough for
camera mounted or shoulder bag applications. This
diversity reception technique effectively minimizes
dropouts in short range situations where multi-path
reflections can cause serious problems. The optimum
diversity reception is realized with the diversity antenna
placed away from the receiver, however, dropouts are
significantly reduced with two antennas mounted directly
on the receiver.

SIX-POLE HELICAL RESONATOR FRONT-END

The UCR195D utilizes a six-pole helical resonator for
front-end filtering. The helical resonators are custom
manufactured in-house to provide the high performance
needed, yet still fit into the small UCR195D package.

This outstanding front-end keeps the UCR195D from
being affected by high power, adjacent RF signals and
also provides extremely high image rejection.

GaAs FET FRONT-END FILTER COUPLING

The UCR195D utilizes an ultra low noise GaAs FET
amplifier in the front-end section to compensate for the
required losses between filter stages. The GaAs FET
devices are extremely quiet, especially at the higher
frequencies in the UHF band.

DOUBLE BALANCED DIODE MIXERS

A double balanced diode mixer is used in the UCR195D
to produce the 10.7 MHz IF signal. The mixer produces
output at only the sum and difference signals, with
minimal spurious signals. This mixer offers a very high
overload threshold and a high degree of isolation be
tween ports. This translates to the ability of the receiver
to accept higher input signals without overloading and
causing distortion and less cross talk between receivers
in multiple system installations.

10 POLE LINEAR PHASE FILTER

The 1st IF amplifier is a 4 stage amp with 2 poles of
filtering after each stage. The filters are high quality,
low distortion, constant group delay ceramic filters. This
special type of filter is needed to accommodate the wide
deviation of the 195 system. The 2nd IF incorporates 2
more poles of filtering.

HELICAL

RESONATOR

GaAS

FET

470 - 608

MHz

XTAL

CONTROLLED

1ST

OSCILLATOR

8 POLE

LINEAR PHASE

FILTER

455KHZ

FILTER

10.7MHz IF

AMP

2ND MIXER

IF AMP

COUNTING

DETECTOR

32 kHZ

BLOCKING

FILTER

HI-LEVEL

DIODE MIXER

XTAL

CONTROLLED

2ND

OSCILLATOR

2:1

EXPANDER

TREBLE

2:1

EXPANDER

BASS

AUDIO

AMP

OUTPUT LEVEL ADJUST

AND

RANGE SWITCH

XLR

OUT

PILOT

TONE

MUTE

HELICAL

RESONATOR

AMP

DISABLE

PILOT

TONE

MOD

AUDIO

LED BARGRAPH METER

AMP

PILOT

LED

ENABLE

REVERSE

POLARITY

PROTECTION

+9V

REGULATOR

PWR

LED

PWR ON

AND

LO BATT LOGIC

TURN ON/OFF

DELAY

CH12 IN

BATTERIES

-8.8V

REGULATOR

INT

OFF

EXT

POWER

SWITCH

32kHZ

V+

METER

MODE

FIXED

ANTENNA

SWITCHING

Figure 1 - UCR195D Block Diagram