Optical incremental shaft encoders are installed at the azimuth and elevation rotational axes. The encoders report
the direction of the antenna (azimuth and elevation angles) through the Control and Data Processor, to the
MARWIN Processor. Rotation is unlimited in azimuth white electronic travel limits are established to prevent
elevation excursion beyond +90 (vertical/zenith) and -5. When operator control of antenna movement is
required, a manual tracking command is entered on the CDU by the operator. This disconnects the motor drive
circuits from the error detector on the Tracking Board and the antenna is manually controlled by the hand-held
CDU through the Control and Data Processor.
The microprocessor based Control and Data Processor supervises, controls, and reports receiver and servo
performance. Built-In-Test (BIT) procedures programmed within the Control and Data Processor are exercised
by command from the Control Display Unit (CDU). The BIT procedures verify correct operation of the AM/FM
Receiver as well as the mechanical and electronic drive and control elements of the servo system. BIT results
are reported to the CDU where they are displayed. The Control and Data Processor communicates with the CDU
and also the MARWIN Processor via individual RS-422 bus connections.
The CDU is a small, self contained unit which is connected and powered via the RDF Antenna through a 100 foot
multi-conductor cable. The CDU liquid crystal display (LCD) is provided with a switch selectable backlight for low
light or night viewing. The CDU is used to:
1) Establish the azimuth and horizontal references for the RDF Antenna pointing mechanisms.
2) Manually control the RDF Antenna pointing position during the first moments of balloon/sonde flight to aid
in acquisition and capture of the sonde track.
3) Activate RDF Unit BIT routines via a selection menu. BIT results are displayed on the CDU LCD.
Additionally, the CDU performs six self tests at power-up to verify integrity of the CDU.
4) Manually control the AM/FM Receiver tuning and AFC.
5) Display pertinent operating data during radiosonde flight. Received signal strength (relative), signal
frequency, and antenna azimuth and elevation pointing angles are presented for operator review.
For more detailed information, refer to TM 11-6660-281-12 and TM 11-6660-281-34.
1-9-4. Digital Communications Terminal (DCT), A3. The DCT provides the digital communication interface to
COMSEC and military radios. Messages can be composed and edited by means of fixed-function and variable-
function switches utilizing a light-emitting diode display. Programs within the DCT enable the device to accept
application programs from another DCT. These programs include bootload, self-test, and purge functions. An
internal "keep alive" battery enables retention of the loaded programs For more detailed information, refer to TM
11-5895-1325-12 & P-7-1.
1-9-5. Power Supply Unit (PSU). A4 and 24 VDC Power Supply. A10. The PSU operates from either 120 VAC,
50 or 60 Hz single phase or +28 VDC primary input power. The PSU switches, fitters, and distributes: 1) AC
power to the MARWIN Processor and 24 VDC Power Supply, 2) +28 VDC output power to the MARWIN
Processor, and 3) +8 VDC output power to the DCT. if the PSU is operating from +28 VDC primary input power
only, the 120 VAC output power is not available.
The 24 VDC Power Supply operates from 120 VAC, 50/60 HZ, single phase input power from the PSU and
provides +24 VDC output power to the RDF Unit.