Lectrosonics Inc IFBT4VHF 사용자 설명서

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.