Lectrosonics SRb_SRb5P - Manual (Page 7)

UHF Digital Hybrid Wireless ®
Rio Rancho, NM 7
The Smart Noise Reduction algorithm has three modes,
selectable from a user setup screen. The optimal setting
for each application is subjective and selected while
simply listening.
• OFF defeats noise reduction and complete trans-
parency is preserved. All signals presented to the
transmitter’s analog front end, including any faint
microphone hiss, will be faithfully reproduced at the
receiver output.
• NORMAL applies enough noise reduction to re-
move most of the hiss from the microphone preamp
and some of the hiss from lavaliere microphones.
The noise reduction benefit is significant in this
position, yet the degree of transparency maintained
is exceptional.
• FULL applies enough noise reduction to remove
most of the hiss from nearly any signal source of
reasonable quality and some high frequency envi-
ronmental noise, assuming levels are set properly
at the transmitter.
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.
Talkback Function
The Talkback function works with the HH hand held
transmitter to use one of the output channels for com-
munication with staff and crew. One of the audio outputs
is connected to the mixer, recorder or house feed. The
other output is connected to a “com” channel.
When the talkback button on the transmitter is pressed,
the audio output on the receiver is switched to the
opposite output jack. When the button is released, the
audio output toggles back to the original output jack.
Turn On and Turn Off Delays
A brief delay is applied when the receiver is powered up
or down to prevent audible noise such as a thump, pop
or other transient noise.
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 UP and DOWN buttons.
Test Tone
To assist in matching the audio levels of equipment
connected to the SRb5P or SRb, a 1 kHz audio test
tone, adjustable from -50 to +5 dBu in 1 dB increments,
is available at the XLR connector. This tone is available
through the TONE setup window.
Power Supply
The SRb5P and SRb is 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 SEL button steps through each of these
windows.
If a battery gets low on one of the transmitters, a mes-
sage 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.