THEORY
Section I. GENERAL
or TT-1/XC-1), the drum rotates at
the rate of revolution per second or 1
Facsimile equipment is used to transmit images
revolution per second, depending on the
over an electrical communication system, These
setting of motor speed control switch
(30RPM-60RPM) S4. The drum travels
minology, may be maps, photographs, sketches,
from right to left along a lead screw at
typewritten or printed text, or handwriting.
the rate of 12 inches in 20 minutes when
a. Operation Performed. The image that serves
revolving at 1 revolution per second, and
as facsimile copy or picture cannot be transmitted
at the rate of 12 inches in 40 minutes
instantly in its entirety. The three operations
when revolving at revolution per sec-
necessary to transmit and record the picture are
ond. Light from an exciter lamp illu-
as follows:
minates a small area of the picture being
(1) The breaking up of the picture in an
scanned and is reflected back through an
orderly manner into a large number of
aperture to a photocell. During the
elemental areas of varying shades. This
transmission of a complete picture, this
process is called scanning and is accom-
light traverses every portion of the pic-
plished by the facsimile transmitter.
ture as the drum slowly spirals past the
(2) Transmission of electrical signals, repre-
fixed lighted area.
senting these individual elemental areas,
to the facsimile receiver.
(2) At any instant, the amount of light re-
Facsimile
flected back to the photocell is a measure
signals are transmitted over wire and
radio circuits.
of the lightness or darkness of the tiny
spot of picture which is being scanned.
(3) The interpreting of these electrical sig-
nals and the rebuilding and recording of
A photocell transforms varying amounts
the original picture from them. This
of light into corresponding electrical
reversal of the transmitter scanning
signals, which are amplified and trans-
mitted over the facsimile circuit.
process is accomplished by the facsimile
(3) Electrical signals received by the fac-
receiver. The receiving transceiver must
simile receiver are amplified and serve
be accurately synchronized with the
to actuate a recording mechanism which
transmitting transceiver to assure satis-
factory reproduction.
makes a permanent record, spot by spot,
on the recording paper on the syn-
AN/TXC-1(*) performs the basic operations
chronized receiver drum until the com-
plete original picture is reproduced.
outlined in a above in the following manner:
Facsimile Set AN/TXC-1(*) reproduces
(1) The picture to be transmitted is mounted
either photographically, with a controlled
on a cylindrical drum, which revolves at
light source shining on photographic
the rate of 1 revolution per second, in
paper film, or directly, with a stylus that
Facsimile Transceivers TT-1/TXC-1,
burns a white protective coating from
TT-1A/TXC-1, T T - 1 B / T X C - 1 and
specially prepared recording paper. Syn-
TT-1C/TXC-1. In Facsimile Sets AN/
TXC-1C and -1D (Facsimile Trans-
chronization is obtained by constantly
driving both receiving and transmitting
ceiver TT-1D/TXC-1, TT-1E/TXC-1,
