NORMARC 7050, Manual

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TRANSMITTER
1-6
21464-5
NORMARC 7050
MARKER BEACON
TX 1373A Transmitter ©1999 Navia Aviation AS
inputs to the FPGA are the strapped signals used to select outer, middle, inner or FAN marker
frequency, as well as status signals regarding oscillator, RF- and LF-level output. Communi-
cation with the FPGA is done by the IOD[7:0], ~TXRD and ~TXWR signals. Multiplying DAC’s
are used to adjust RF level and modulation depth. The keyed LF signal and the RF level is
applied to the Modulation Control Circuits. The modulation voltages to the PA is generated by
the use of these signals as well as the ON/OFF signal from the AGC and the detected signal
from the PA.
MAINTENANCE / MONITOR CIRCUITRY
The purpose of the onboard monitor circuitry is to give the Monitor card MO 1374 information
about the status of the transmitter. The AMUX_ADR[3:0] from the MO 1374 is applied to the
analogue multiplexer. These four lines select one of sixteen possible signals to be measured.
The signals measured are:
•
PA 20 VDC supply voltage
• PA current drain @ 20 VDC
• Detected RF level from demodulator
• Keying envelope from demodulator
• Positive/negative modulation peaks
• LF AGC voltage
• Driver AGC voltage
• RF level DC voltage from LF generator
• Supply voltage status
The signal information is sent to the MO 1374 monitor unit as a differential analogue test sig-
nal from the MUX.