Lectrosonics UCR411a - Manual (Page 6)

UCR411A
LECTROSONICS, INC. 6
The UCR411A is a portable, high performance, triple-
conversion, frequency synthesized, UHF receiver fully
compatible with all Lectrosonics 400 Series transmitters
(and some other transmitter types – see Compatibility
Modes for details). The RF performance is extremely
stable over a very wide temperature range, making the
UCR411A perfectly suited to the rough environmental
conditions found in the field. The proprietary audio pro-
cessing includes a digital signal processor for very low
distortion and a superior signal-to-noise ratio.
The UCR411A front panel features a menu-driven LCD
graphic display and three control buttons to conve-
niently view and alter user settings. The main window,
for example, displays the pilot tone indicator, antenna
diversity phase, RF level, audio level, receiver battery
status and transmitter battery status. It is also possible
to bypass the pilot tone/squelch from the main display
window. Other windows display operating frequency,
audio output level, battery voltage and test tone status.
The frequency scan mode provides a spectrum analyz-
er for a graphical means of observing all signals “on the
air” within the frequency range of the receiver in order to
find operating frequencies that are free of interference.
Compatibility Modes
The UCR411A receiver was designed to operate with
Lectrosonics 400 Series transmitters and will yield the
best performance when doing so. Due to the flexibility
of digital signal processing, the UCR411A is also able
to operate with Lectrosonics 200 Series, Lectrosonics
100 Series, IFB Mode, as well as Modes 3 and 6, which
work with certain non-Lectrosonics transmitters.
Diversity Reception
The UCR411A technology with SMARTDiversity ™ mini-
mizes dropouts in situations where multi-path reflec-
tions can cause serious problems. The phase diversity
network and PIN diode RF switches are controlled by
the microprocessor using a sophisticated algorithm to
use both antennas simultaneously. This design keeps
the receiver compact enough for camera mounting or
shoulder bag applications, yet provides effective diver-
sity reception.
RF Frequency Tracking Front-End and Mixer
The receiver is frequency agile and can be set to oper-
ate on any one of 256 frequencies within its tuning
range. To significantly reduce unwanted interference
and intermodulation problems, the UCR411A has a fre-
quency selective front-end section that tracks and tunes
to the desired signal frequency and rejects or “tunes
out” unwanted interfering signals. The design consists
of four varactor tuned ceramic transmission line resona-
tors controlled by the microprocessor to provide good
selectivity. The low noise high current RF amplifier was
designed with feedback regulation for stability and pre-
cise gain in order to handle stronger RF signals without
output overload. The first mixer is of new GaAs technol-
ogy that has a very high third order intercept point. This
produces a robust front-end that is as selective as fixed
single frequency designs and is suitable for use in close
proximity to other receivers and transmitters commonly
used in field production “bag” systems.
Microcontroller, PLL and VCO Circuits
The 8-bit microcontroller is truly the “heart” of the
UCR411A receiver. It monitors user command inputs
from the front panel control buttons and numerous other
internal signals such as RF level, audio levels, pilot tone
levels and external/internal power voltages. Outputs
from the microcontroller drive the LCD display and
backlight, control the squelch and audio output attenu-
ator, and operate the front-end tuning, the PLL/VCO
circuits and the antenna phase switch. The UCR411A
design and the advanced technology of the micropro-
cessor control arguably set a new standard in wireless
microphone development.
General Technical Description
UCR411A Block Diagram