Lectrosonics T1 - Manual (Page 6)

T1
Pilot Tone
The T1/R1A system uses an ultrasonic tone modulation
of the carrier to operate the receiver squelch. This “pilot
tone” consists of a 29.997 kHz signal which is mixed
with the audio signal just after the compandor. The pilot
tone controls the audio output muting of the receiver
and is filtered out of the audio signal immediately after
the detector in the receiver so that it does not influence
the compandor or various gain stages.
The benefit of the pilot tone squelch system is that the
receiver will remain muted until it receives the pilot tone
from the matching transmitter, even if a strong RF
signal is present on the carrier frequency of the system.
Frequency Synthesizer
The transmitter uses a synthesized, frequency select­
able main oscillator. The frequency is extremely stable
over a wide temperature range and over time. Two
push-button switches, located on the front panel of the
unit, provides the user with 256 frequencies in 100 kHz
steps over a 25.5 MHz range. This significantly allevi­
ates carrier interference problems in mobile or traveling
applications.
Power Delay
There is a five second power-ON/OFF delay to prevent
audio thumps when switching from XMIT to TUNE or
from TUNE to OFF. This delay also gives the Fre­
quency Synthesizer time to fully stabilize. When the
transmitter is powered OFF, the Pilot Tone is first turned
off muting the audio at the receiver before the rest of
the transmitter is powered down. This prevents clicks,
thumps or feedback from entering the sound system.
Microcontroller
Frequency adjustment and display are handled by the
microprocessor. Nonvolatile memory is provided for
holding the last frequency used, even if power is
removed from the unit for any length of time. Each time
the transmitter is powered up, it will display the last
frequency used.
Transmitter
The T1 transmitter operates at 250 mW, more powerful
than most IFB systems on the market today. The higher
power ensures a clean signal free of dropouts and
noise. The transmitter circuits are buffered and filtered
for exceptional spectral purity. The extra clean signal
that results reduces the chances for interference
between multiple transmitter installations.
Antenna System
The antenna on the T1 consists of a flexible 1/4 wave­
length bronze cable, detachable via a BNC connector.
The 50 ohm output connector works conveniently with a
variety of remote antennas for installation in studios and
production trucks & vans.
LECTROSONICS, INC. 6