Codan Radio Communications VT-3-150-SN User Manual
Audio Processor Board Instruction Manual
1-1
1
FM AUDIO PROCESSOR
1.1
Introduction
The MT-3 FM Audio Processor is a versatile circuit board that can provide several types of audio
processing for voice or data transmission.
The following terms are defined:
processing for voice or data transmission.
The following terms are defined:
Table 1
Bandwidth Definition
Term
Channel Spacing
Rated System Deviation
Wideband
25 kHz or 30 kHz
±5.00 kHz
Narrowband
12.5 kHz or 15 kHz
±2.50 kHz
LTR™ is a trademark of E.F. Johnson Co.
Features include:
•
Automatic level control using a compression amplifier with a 25 dB dynamic range
•
Limiter and Splatter filter that removes noise and harmonics
•
Selectable pre-emphasis or flat audio response
•
Temperature compensated audio output
•
Ability to transmit data and voice switched by a single control line.
•
Backwards compatible with Daniels Electronics MT-2 series transmitters.
•
Direct modulation input for LTR™, DCS, paging and other digital modulations that
require very low frequency modulation to the synthesizer or crystal oscillator module.
require very low frequency modulation to the synthesizer or crystal oscillator module.
•
Separate voice and direct modulation outputs, each individually configurable.
•
Multiple jumpers that can be configured to allow maximum flexibility in routing signals
from inputs to outputs, and disabling selected circuits to reduce operating current.
from inputs to outputs, and disabling selected circuits to reduce operating current.
•
Dual microphone and balanced audio compression circuits.
•
On-board multi-configurable temperature compensation to correct for changes in
transmitter deviation over temperature caused by changing characteristics of synthesizers
and oscillators.
transmitter deviation over temperature caused by changing characteristics of synthesizers
and oscillators.
•
A single chip 10th Order Linear Phase Lowpass splatter filter for increased cutoff
attenuation responses needed in today’s narrow band environment.
attenuation responses needed in today’s narrow band environment.
•
The ability to switch between narrow and wideband through a single control line which
can be externally controlled. This can be useful when configured as a multi-channel
transmitter which uses mixed wide and narrowband frequencies.
can be externally controlled. This can be useful when configured as a multi-channel
transmitter which uses mixed wide and narrowband frequencies.
•
The ability to easily reconfigure fixed operations from narrow to wideband through
simple jumper settings
simple jumper settings