TM 11-5821-333-30
2-2. CONTROL SECTION
The control section has four modules:
Electronic Components Assembly - Control 1A2 (control module)
Control, Counter-Countermeasures, Electronics 1A3 (ECCM module)
Circuit Card Assembly - Interface 1A4 (interface module)
Circuit Card Assembly - Switching 1A5 (switching module)
The control module contains a microprocessor and all programming needed for single channel operation. The
microprocessor uses additional programming in the ECCM module during frequency hopping operation. The
control module has buffers, registers, and interface circuits to permit the microprocessor to communicate with
other rt modules. The control module receives operator actions as serial data from the front panel. If the opera-
tor’s actions are valid, the other modules and the front panel display are informed of any changes. The control
module microprocessor also tunes the frequency synthesizer and runs the self test when the FUNCTION switch is
set to TEST.
The ECCM module contains a 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 and uses variables stored 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, and hopset 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 detail in paragraph 2-15.
The interface module processes several information and control signals. It performs the following functions:
Filters and amplifies receive voice signals, adds sidetone,
Filters, amplifies, pre-emphasizes, and compresses transmit voice signals,
Buffers and amplifies transmit and receive 16 kb/s data signals,
Detects and debounces transmit push-to-talk (PTT) signal input from intercom,
Processes homing antenna signals to drive homing indicator,
Buffers input ECCM fill information,
Buffers IFM power amplifier control signals,
Monitors the +28 V line for low voltage condition, Supplies a reset to front panel when voltage drops to
about +18 V.
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 (150 Hz)
Module 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
