e. End of message assembly. The end-of-message assembly also rides on the guide bars and
contains the margin stop lamp. The assembly is positioned manually by the operator at the required
margin stop position using the carriage STOP handle.
Electronic/Electromechanical Principles. By scanning a spiral path on the drum, the LDF uses a
raster-scan technique to collect images from the input copy by photo-optical means, transmits these
images to a receiving LDF (in Mode A) or to memory (in Mode B), and prints out the images on a
a. Scanning. The light from the lamp of the scan-optic assembly is focused on the input copy.
Where the light strikes the copy, the image under the light is magnified and projected by a lens onto an
aperture in front of a photocell. The photocell converts the light into electrical signals for eventual
transmission or storage of data. The scan-optic lens requires periodic cleaning with a brush as described
in Chapter 3, TM 11-5815-615-10.
b. Printing mechanism. The printing mechanism transducer translates an electrical signal which
varies the pressure of a stylus on the output copy. The pressure of the stylus prints the images on the
output copy using carbon paper. Digital video operations produce either maximum pressure marks or
no-pressure white spaces. Analog video operations produce varying pressure that result in white spaces,
gray shades, or black marks. Build up of dust and other materials is removed by cleaning with a brush
as described in Chapter 3, TM 11-5815-615-10.
Principles of Operation. The LDF is used to send and receive images over long distances. The
images can be printed text information such as letters or other messages which are called black and
white, or they can be photographs or maps which are called gray shade materials. These materials are
called gray shade because they contain tones between black and white. An operable system consists of
two LDFs and a communications link. The communications link allows the two LDFs to either
transmit/receive data or communicate by voice. The LDF has two separate modes of operation, Mode A
and Mode B.
a. In Mode A, images are scanned and transmitted from one machine to another machine that
receives and prints as the transmitted information arrives.
b. When any of the Mode B conditions are selected, the LDF becomes much more
Each LDF has an image memory, a transmit memory, a receive memory,
and supporting electronic functions which are now activated. Pressing the MEMORY LOAD
switch causes processed scanner data to be entered into the image memory from where
it can then be appropriately formatted for rapid transmission (called burst operation)
from the transmit memory into the receiving LDF's receive memory. The data can now be