Lectrosonics UCR401 - Manual (Page 9)

UHF Digital Hybrid Wireless ® Receiver
Rio Rancho, NM 9
Supersonic Noise-Based
Dynamic Filter and Squelch
In addition to SmartNR, all hybrid receivers are
equipped with a supersonic noise-based dynamic filter
and squelch system. The incoming audio is monitored
for energy above 22 kHz, pilot tone excepted. Excessive
high frequency energy indicates that the received signal
is too weak to achieve an acceptable signal-to-noise
ratio. Under marginal conditions, a variable low pass
filter is rolled in dynamically, masking the noise while
preserving as much of the transmitted signal as pos-
sible. When the channel is too noisy even for the filter,
the audio is squelched.
This noise-based filter and squelch system replaces a
more or less equivalent system used for many years,
which based its operation on RF signal strength. Perfor-
mance of the two systems is virtually identical, but the
noise-based system requires no calibration and there
is no better way to track the signal-to-noise ratio than to
measure it directly.
RF-Controlled Digital Noise Filter
In extremely weak signal conditions, an RF sensitive
variable frequency filter is applied to reduce the high
frequency response of the receiver. This filter does
nothing until the RF signal strength drops below 3 uV at
which point it begins to roll off high frequencies. Usable
audio remains unaffected, but noise-ups or “hits” occur-
ring near the fringe of reception sound much less harsh.
Audio Output Level
A setup screen is provided for adjusting the audio out-
put level in 1 dB increments from -50 to +5 dBu using
the front panel SEL Up and Down buttons.
Test Tone
To assist in matching the audio levels of equipment con-
nected to the UCR401, a 1 kHz audio test tone, adjust-
able from -50 to +5 dBu in 1 dB increments, is available
at the XLR connector. This tone is available through the
TONE display window.
Batteries
The UCR401 operates on two AA 1.5 Volt alkaline,
lithium or NiMH batteries. Access to the battery com-
partment is gained by lifting one end and turning the
rear panel door.
Note: Do not mix battery types in the same unit.
Also, standard or “heavy duty” batteries are not
recommended.
Power Supply
The UCR401 may be operated from an external DC
power source. The power supplies are protected from
damage to the receiver that could occur if a positive
ground power source is applied.
LCD Display
The display has four primary windows. Pressing the
Front Panel MENU button steps through each of these
windows.
If the battery gets low on either transmitter or receiver,
a message will interrupt the display every few seconds
and flash a low battery warning.
After power is turned off and back on again, the unit
defaults to the main window and to the most recent fre-
quency, audio level, transmitter battery type and other
user settings. These settings are retained even if the
batteries are removed. After five minutes of no key ac-
tivity, the LCD backlight goes off and the display reverts
back to the main window.
Power Up Sequence
The power up sequence consists of four messages that
appear automatically after the power is switched on.
1) UCR401
BLK xx (xx is the frequency block number)
2) VERSION
R.R/A.A (R.R is the RF board firmware version,
A.A is the audio board firmware version)
3) COMPAT
mode (mode is one of the following:
400 - Native 400 Series mode
100 - Lectro 100 Series compatibility
200 - Lectro 200 Series compatibility
MODE 3 - compatible with certain
non-Lectrosonics transmitters)
IFB - compatible with all Lectrosonics IFB
transmitters.
MODE 6 - compatible with certain
non-Lectrosonics transmitters)
4) TUNING
mode (mode is one of the following:
NORMAL - tune in single channel increments
GRP x - tune in precoordinated intermod-free
frequencies (x is A, B, C, D, U or V))
The Main Window appears after the introductory mes-
sages are displayed.
The UCR401 is fully operational during the power
up sequence and will immediately respond to button
pushes made before the automatic sequence is com-
pleted. If a valid transmitter signal is already present
when the receiver is turned on, the audio output will
typically be engaged somewhere in the middle of the
power-up sequence, following a brief delay to allow the
audio circuits to stabilize.
Power Off
When the Front Panel Power ON/OFF switch is moved
to the OFF position, the audio output is instantly muted
(squelched) and the message “POWERING OFF...” is
displayed briefly before the receiver switches off.