Page 6-18 Vector-LP Radio Beacon Transmitter Technical Instruction Manual
Issue 1.1 Section 6 Theory of Operation
6.5.1.3.2 Forward Power
The Fwd Pwr Sample input (J1-3) is a dc
voltage which represents the forward power at
the transmitter’s RF output. The input is filtered
through operational amplifier U2D and
associated components. A fwd_pwr_sample
signal is applied to ADC U9 for application to
the front panel’s diagnostic display. The
fwd_pwr_sample input is also applied to the
remote interface PWB via the external serial
interface (microcontroller U22). The Fwd Pwr
Sample input is also low-pass filtered through
operational amplifier U2C and associated
components. A speaker_ref_level signal is
applied through DAC U32. The analog output
(pin 12) is filtered through operational amplifier
U28D and associated components and applied
to the Audio (Speaker) output (J11-1), then
applied to speaker LS1 for audio monitoring.
6.5.1.3.3 Battery Voltage
The Battery Voltage input (J1-27) is a dc
voltage which represents the voltage applied
from the transmitter’s optional battery supply.
The input is filtered through operational
amplifier U3B and associated components.
The bat_volt_sample signal is applied to ADC
U12 for application to the front panel’s
diagnostic display.
6.5.1.3.4 Battery Current
The Battery Current input (J1-25) is a dc
voltage which represents the current drawn
by the transmitter’s optional battery supply.
The input is filtered through operational
amplifier U3A and associated components.
The bat_cur_sample signal is applied to ADC
U12 for application to the front panel’s
diagnostic display.
6.5.1.3.5 Low Voltage Power Supplies
Attenuated, buffered samples of all low
voltage dc power supplies (+24 V, r 15 V and
+ 5 V) are applied to ADCs U9 and U12 for
application to the front panel’s diagnostic
display.
6.5.1.3.6 Cabinet Temperature
Low voltage temperature sensor U5 provides
a dc voltage (between 0 and 5 V) which
represents the ambient cabinet temperature.
This voltage is buffered by operational
amplifier U8A and associated components
and applied to ADC U12 for application to the
front panel’s diagnostic display.
6.5.1.4 MICROCONTROLLER
Microcontroller IC U22 interfaces between the
diagnostic display and its associated soft-
keys. It controls the level of the Carrier Ref
signals (see paragraph 6.5.1.1), which
ultimately determines the forward power level
of the transmitter. It also acts as an internal
and external serial interface for transmitter
alarm and status signals.
6.5.1.5 CPLD
Complex programmable logic device (CPLD)
U18 continuously reads digital inputs for all
transmitter alarm events. It is programmed to
perform root cause detection of a fault as well
as high-speed fault protection. Depending on
the nature of the fault, the CPLD generates
transmitter Shutback outputs (J7-1 and J7-2)
or various digital control/inhibit signals via a
parallel data bus.
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