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TM 11-5820-890-30-5
2-2.
CONTROL SECTION. Continued
The control module contains a microprocessor and the programming used in single channel operation. Buffers,
registers, and interface circuits are included to permit the microprocessor to communicate with the other RT
modules. It checks the FCTN, MODE, RF, and CHAN switches and the keyboard for operator action. If the
operator’s actions are valid, the other modules and the front panel display are informed of any directed changes.
Control signals are described in paragraph 2-14.
The ECCM module contains another microprocessor and the programming used in frequency hopping operation.
The ECCM module has two connectors. One connects to the control module and the other to the RT chassis.
When the MODE switch is set to FH or FH/M, the microprocessor in the control module executes instructions in
the ECCM module. It uses the hopset and lockout sets to build a look-up table of frequencies. The TRANSEC
variable, FH sync time (TOD), and net ID number are used to select a frequency from that table. When
transmitting, the ECCM module converts the analog signal into a digital data signal. The ECCM module
microprocessor interleaves the data signal onto the frequency hops. When receiving, the process is reversed.
Frequency hopping operation is described in paragraph 2-15.
The remote l/O module and two-wire interface provide the remote operating capability. The two-wire interface
sends and receives information to and from the remote control unit over a two-wire link. Control information is
encoded using frequency shift keying (FSK). It converts instructions received into a digital data stream for the
remote I/O module. A microprocessor in the remote l/O module interprets the instructions and exchanges data
with the control module. During remote operation, the control module executes instructions from the remote I/O
module instead of the front panel. Remote operation is described in detail in paragraph 2-19. (Also see Chapter 6
on the control-monitor.)
The switching module functions like a railroad switching yard. Many signals are routed between modules through
the switching module. The path the signals take is determined by control input signals. It also performs the
following functions.
Bit synchronization.
Premodulation filtering.
Tone squelch.
Notch Filtering.
Modulation level control.
Generation of clock frequencies using the 3.2-MHz clock signal from the synthesizer.
Input and output control during retransmit operation.
The switching module is involved in most functions of the RT.
2-3.
RF SECTION.
The RF section consists of five modules. They are:
Network, Impedance Matching 1A1
lF/Demodulator 1A8
Tuner/Mixer 1A9
Synthesizer, Electrical Frequency 1A10 (synthesizer)
Exciter/Power Amplifier 1A11
The module locations are shown in figure 2-4.
2-5
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