Lectronics IFBT4-VHF, Инструкция по эксплуатации

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Synthesized VHF IFB Transmitter
Rio Rancho, NM
5
Digital Hybrid Wireless
®
Technology
The design is based upon the patented Lectrosonics
Digital Hybrid Wireless
®
system.* While at the time of
the first release of the product, there is only a compan-
ion analog receiver, the Digital Hybrid Wireless system
is included for compatibility with future products.
Audio Signal Processing
Lectrosonics IFB systems use a single band compan-
dor and pre-emphasis/de-emphasis to reduce noise.
This signal processing is generated and applied by the
DSP for accuracy and clean handling of signal dynam-
ics.
The DSP also provides the ability to employ compat-
ibility modes for use with other wireless equipment in
the VHF spectrum that may come along in the future.
Pilot Tone Squelch System
Lectrosonics IFB systems use a supersonic “pilot
tone” to control the squelch activity in the receiver. A
valid RF signal will include the pilot to signal the audio
output to open. Even strong interference on the same
frequency cannot open the audio output if the pilot
tone is not present.
During normal operation, an IFB receiver will listen for
the distinctive pilot tone, remaining silent (squelched)
until the pilot tone is detected. The pilot tone is located
well above audio frequencies and is never passed
through to the receiver’s audio output.
Frequency Agility
The IFBT4 transmitter uses a synthesized, frequency
selectable main oscillator. The frequency is extremely
stable over a wide temperature range and over time.
The transmitter’s standard tuning range covers 239
frequencies from 174 to 216 MHz in 175 kHz steps. to
alleviate interference problems in mobile applications.
Power Delay
When powering the transmitter on and off, and when
switching between the XMIT and TUNE modes, intel-
ligent circuitry adds brief delays in order to allow time
for circuits to stabilize, both locally and in the match-
ing receiver. These delays prevent clicks, thumps and
other noise in the audio.
Microcontroller
The microcontroller oversees most system operations,
including RF frequency and output, DSP audio func-
tions, buttons and display, and more. User settings are
stored in non-volatile memory, so they are retained
even when the power is turned off.
Transmitter
The transmitter operates at the maximum allowed RF
power level to ensure a clean signal free of dropouts
and noise. All transmitter circuits are buffered and
filtered for excellent spectral purity. The clean trans-
mitted signal reduces the chances for interference in
multiple transmitter installations.
Antenna Port
The 50 Ohm BNC output connector will work with stan-
dard coaxial cabling and remote antennas.