NORMARC 7050, Manual

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©1999 Navia Aviation AS 21464-5 TX 1373A Transmitter
TRANSMITTER NORMARC 7050
MARKER BEACON
1-3
TRANSMITTER DESCRIPTION
1 TX 1373A Transmitter
1.1 General Description
TX 1373A is a module designed to transmit Marker Beacon signals. An on board oscillator
working at 75 MHz provides an output of app.0 dBm that is used as input to the Power Ampli-
fier (PA). The level of this input signal is adjusted to an output of app. +20 dBm. The Power
Amplifier is capable of delivering up to 4W carrier power at the cabinet output.
Unwanted frequencies are removed by a lowpass filter after the PA. Part of the signal out of
the PA is tapped off to be demodulated and used for feedback and self test purposes. Demod-
ulation is done by a mixer with a linear detector.
The audio signals are generated in the LF circuitry mainly by a Field Programmable Gate
Array (FPGA). Inner, Middle or Outer Marker is selected by straps.
1.1.1 Block diagram
Figure 1-1 TX1373 Block diagram
1.1.2 Signals
Oscillator
Modulation detector
LP filter
Power Amplifier Automatic Gain Control
RF OUT
LF Generator
Maintenance/
Monitor
Modulation Amp
Modulation Control
AMUX_A[3:0]
DAC_DATA[7:0]
DAC_CTRL
MODULATION / BIAS
RF LEVEL / IDENT
MAINTENACE SIGNALS
DET_SIGNAL
TXCS
TXWR
TXRD
IOD[7:0]
TX_CTRL_BUS
TRANSMIT
TRANSMIT
RMS_LEV[1:0]
A_TX[P,N]
HBK817-1