REF ID:A36245B 

Patented May 15, 1951 2 552 548 

' ' 

UNITED 

1 

STATES PATENT 

2,552,548 

FACSIMILE ENCIPHERING SYSTEM 

William F. Friedman, Washington, D. C. 

Application March 6, 1943, Serial No. 478,193 

5 Claims. (Cl. 178-5.1) 

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 

OFFICE 

2 

The invention described herein may be manu- Figure 3 is a circuit diagram of the receiver 

factured and used by or for the Government for in block form. 

governmental purposes, without the payment to In the one embodiment of my invention which me of any royalty thereon. has been selected from among others, my device 

The subject matter of this invention is a sys- r) is shown as comprising a transmitter section 

tem for enciphering facsimiles. having a motor I driving shaft 2 carrying transThis invention relates to means for secretly parent drum 3 surrounded by message sheet 4 

communicating information by transmitting a and also carrying transparent drum 5 surrounded 

facsimile of the message in a graphic form of by control sheet 6. Within drums 3 and 5 are any sort such as a writing, type-writing, pie- JO located electric lamps 7 and 8 which serve as ture, photograph or the like. Secrecy 1s obtained sources of light and which are energized from a by transmitting a series of impulses caused in source of electricity 9. Opposite lamps 7 and B 

part by the message to be transmitted and in so as to receive a beam of light therefrom and, 

part by a control in graphic form such as any respectively, under the control of message sheet 

writing, picture or random arrangement of dots 15 4 and control sheet 6, are located light-sensi- or lines. Such a control does not necessarily tive cells I 0 and 11 which form parts of cirhave any intelligibility in itself. It operates as cuits including amplifiers 12 and 13 and relay a random key. At the receiving end, a dupli- coils 14 and 15. These relays also include mov- cate of this control 1s employed. This dupllcate able contacts 16 and 11 biased in one direction 

control is moved in synchronism with the move- 20 by springs 18 and 19 and, in the other direction, 

ments of the control at the transmitting end and by coils 14 and 16, respectively, when these coils causes a series of impulses which co-operate with are energized, and engaging one or the other of 

the impulses received from the transmitter, the stationary contacts 20 and 21. Contacts 16, 1 l, 

Interaction between the two series of impulses 2'0 and 21 form parts of a circuit, including a serving to produce a facsimile of the original 25 source of current 22 and rela~· coil 23, which, 

message. when energized, attracts movable contact 24 into 

It 1s an object, therefore, of my invention to engagement with stationary contact 25, over- provide apparatus comprising a transmission sys- coming the pull of spring 26. Contacts 24 and 

tem including a transmitter section and a re- 25 control a circuit including transmitter 2l 

ceiver section. Each of said sections has, as a ::o having an output element 28, shown as an an- part thereof, an electric circuit including the tenna. 

contacts of a plurality of relays interconnected At the place to which it is desired to transln such a way as to cause a plurality of impulses mlt the intelligence, there is located a receiving 

to circulate in said circuit. In the transmitter system having a receiving element, indicated 

section these impulses represent the combined ;{::; as an antenna 29, forming part of receiver 

effects due to the message to be transmitted and 30 which is connected into circuit so as to con- to a control element. An impulse can only occur trol relay coil 31. This relay also includes mov- ln this circuit when both of the relays have not able contact 32 stressed away from coil 31 by 

moved their contacts to the same position. In spring 33 and co-operating with stationary con- the receiver section these impulses represent 40 tacts 34. Motor 35 drives shaft 35 carrying transthose caused by the original message, since the parent drum 31 surrounded by second control 

impulses due to the control have been removed sheet 38, which is a duplicate of control sheet 

by the use of a duplicate of the control in the 6. Within drum 31 is located electric lamp 39, 

receiver section. energized by a source of electricity 40. OppoFor a further exposition of my invention refer- 45 site lamp 39 so as to receive a beam of light ence may be had to the annexed drawings and therefrom under the control of second control 

specification at the end whereof the novel fea- sheet 38, is located light-sensitive cell 41 which 

tures of my invention will be specifl.cally pointed forms a part of a circuit including amplifier 42 

out and claimed. and relay coil 43. This relay also includes mov- In the drawings: 60 able contact 44 biased in one direction by spring 

Figure 1 is a circuit diagram of the transmit- 45 and, in the other direction, by coil 43, when 

ter with parts designated by blocks bearing ap- this coil ls energized, so as to engage one or propriate labels. the other of stationary contacts 46. Contacts 34 

Figure 2 is a tabulation illustrating the im- and 46 form parts of a circuit including a source pulses com risin the in 1 e 6li f lectricit 41 and a rela coil 48. This re-: 

roved for Release b NSA on 07-22-2014 ursuantto E.O. 1352 
REF ID:A36245B 

3 

lay includes movable contact 49 stressed away 

from coil 48 by spring 50 and co-operating with 

stationary contact 51. Contacts 49 and 51 are parts of a circuit including a source of electricity 

52 and coil 53, which is the operating element 

of a facsimile reproducer of any convenient type. 

The operation of my device is as follows: The 

message and the control sheets are in any graphic 

form such as a writing, printing, drawing, photograph or the like. They may be said to consist 

of pluralities of spots or elemental parts each of 

which is either black or white depending upon 

the part of the message which it foxms. Relative movement is provided between lamp 1 and 

message sheet 4, between lamp 0 and control sheet 

6, and between lamp 39 and second control sheet 

38 in any convenient manner heretofore used in 

the art of facsimile transmission. This causes the beam of light emitted by each lamp to scan every spat or element of the message or control 

associated with it. In the transmitter this scanning thus produces a series of impulses in the 

amplifying circuits through the action of the light 

sensitive cells I 0 and 11. For convenience of description, these impulses can be said to be produced by black spots in the message or control. 

Thus coils 14 and 15 are energized every time 

an impulse occurs in the amplifying circuit associated therewith. The action of the relays con- trolled by these coils produces in the circuit associated with them a series of impulses distributed 

in time as shown in Figure 2 of the drawings in 

which the term "X" represents an impulse. This 

figure shows the four possible cases. Thus it will 

be seen in column 1 that energizing coil 14 by 

message sheet 4 without energizing coil IS by con- trol sheet 6 causes an impulse in the circEit containing coil 23 and labeled "Result" in Figure 2. 

This energizes coil 23 and causes transmitter 21 

to emit an impulse. As seen in column 2, when 

both coils 14 and 15 are energized no impulse 

appears in the circuit containing coil 23. As seen in column 3, energizing coil 15 but not energizing 

coil 14 causes an impulse in the circuit containing 

coil 23. Column 4 shows that when no impulse is 

present in either amplifier 12 or 13 and, conse- quently, neither coil 14 nor 15 is energized, no impulse appears in the circuit containing coil 23. 

To put it another way, an impulse oniy appears 

in coil 23 and, therefore, an impulse is only sent 

out from transmitter 21, when coils 14 and 15 are not in the same condition, i. e., are not simultaneously energized or de-energized. This is due 

to the fact that simultaneous energization or deenergiza tion of coils 14 and i 5 causes movable 

contacts 16 and 11 to engage stationary contacts 

20 and 21, respectively, which are connected to 

the same side or polarity of source 22. 

The series of impulses emitted by the output 

element 28 of transmitter 27 is received by the 

input element 29 of receiver 30. Each impulse so received energizes coil 31. Motor 35 produces 

relative movement between second control sheet 

38 and light 39 so that control sheet 38 is scanned 

in synchronism with control sheet 6. Since sec- ond control sheet 38 is a duplicate of control sheet 

6, coil 43 is energized in synchronism with the 

energizations of coil 15. Referring again to Fig- ure 2, the line labeled "Result" represents the 

impulses which pass through receiver 30 and energize coil 31, while the line labeled "Control" represents the simultaneous impulses caused by control sheet 38 and which energize coil 43. Figure 2, 

column I, shows that when there is an impulse 

in coil 31 and none in coil 43, an impulse is pro4 

duced in coll 48, which is represented in Figure 2 

by the line labeled "Message." Following 

through the other columns of Figure 2 shows 

that when coils 31 and 43 are simultaneously 

ti energized or de-energized, no impulse appears in 

coil 48. Likewise, while either coil 31 or 43 is 

energized when the other is de-energized, coil 48 

is energized. The energization of coil 48 causes 

coil 53 to be energized and coil 53 operates a 10 stylus or other marking mechanism and thus 

message sheet 4 is reproduced. 

It will be understood that, whereas the foregoing description calls for the transmission of a signal when one only of the coils 14 and 15 is ener- 15 gized, the apparatus will function just as well and 

achieve just as great privacy if rearranged 

slightly, as by giving an opposite bias, a normal 

closed condition, to switch 24-25. In such case, 

of course, a signal will be transmitted whenever 

20 coils 14-15 are in the same condition instead of 

when they are in different conditions. 

I claim: 

1. Means for secretly transmitting graphic information, said means comprising, a message in 

25 graphic form which it is desired to transmit, a scanner arranged to scan and reproduce said 

message as a series of electric impulses of varying intensity, a screen having varying portions, 

<t second scanner arranged to scan and reproduce ~-!O the variations of said screen as a second series of 

electric impulses of varying intensity, a relay 

connected under the control of said scanner and 

arranged to be moved by each of said impulses 

to one of two positions, a second relay connected 

;>;i under the control of said second scanner and 

arranged to be moved by each of said second impulses to one of two positions, an electric circuit 

including parts of said relays and adapted to be 

closed only when there is instantaneously an im41.l pulse in either series but not in the other, a transmitter connected under the control of said 

electric circuit so as to emit impulses whenever 

said circuit is closed, a receiver arranged to re- ceive the impulses emitted by said transmitter 

4ii and having an output comprising a third series 

of electrical impulses of varying intensity, a second screen duplicating said first mentioned 

screen, a third scanner arranged to scan synchronously with the scanning of said second scanner 

50 and reproduce the variations of said second screen as a fourth series of electric impulses of varying 

intensity, an electromechanical interlock con- nected under the control of said third and of said 

fourth series of impulses and arranged to be ener- 65 gized wheneve1· an impulse occurs in one of said 

third and fourth series and no impulse occurs simultaneously in the other of said third and 

fourth series, and a recorder connected under the 

control of said interlock and arranged to operate 

60 whenever said interlock is energized and to 

thereby reproduce said message. 

2. Means for secretly transmitting graphic information, said means comprising, a message in 

graphic form which it is desired to transmit, a 

65 scanner arranged to scan and reproduce said mes- sage as a series of electric impulses of varying 

intensity, a screen having varying portions, a second scanner arranged to scan and reproduce 

the variations of said screen as a second series of 

70 electric impulses of varying intensity, an electromechanical interlock connected under the control 

of both of said series of impulses and arranged 

to be energized whenever an impulse occurs in 

one of said series and does not occur simultaneTti ously in the other of said series, a transmitter 
REF ID:A36245B 

2,IU~2,G48 

5 

connected under the control of said interlock so as to emit impuises whenever said interlock is 

energized, a receiver arranged to receive the impulses emitted by said transmitter and having an output comprising a third series of electrical 5 

impulses of varying intensity, a second screen duplicating said first mentioned screen, a third scanner arranged to scan synchronously with the 

scanning of said second scanner and reproduce 

the variations of said second screen as a fourth 10 

series of electric impulses of varying intensity, a second electro-mechanical interlock connected 

under the control of said third and of said fourth 

series of impulses and arranged to be energized 

whenever an impulse occurs in one of said third Hi 

and fourth series and no impulse occurs simultaneously in the other of said third and fourth 

series, and a recorder connected under the control 

of said second int€rlock and arranged to operate 

whenever said second interlock is energized and 20 

to thereby reproduce said message. 

3. Means for secretly transmitting graphic information, said means comprising, a message in 

graphic form which it is desired to transmit, a scanner arranged to scan and reproduce said 25 

message as a series of electric impulses of varying 

intensity, a screen having varying portions, a second scanner arranged to scan and reproduce 

the variations of said screen as a second series 

of electric impulses of varying intensity, a relay 30 

connected under the control of said scanner and 

arranged to be moved by each of said impulses 

to one of two positions, a second relay connected 

under the control of said second scanner and ar- ranged to be moved by each of said second im- 311 

pulses to one of two positions, an electric circuit 

including parts of said relays and adapted to be 

closed only when there is instantaneously an impulse in either series but not in the other, a transmitter connected under the control of said 40 

electric circuit so as to emit impulses whenever 

said circuit is closed, a receiver arranged to re- ceive the impulses emitted by said transmitter 

and having an output comprising a third series of 

electrical impulses of varying intensity, a second 4G 

screen duplicating said first mentioned screen, a third scanner arranged to scan synchronously 

with the scanning of said second scanner and 

reproduce the variations of said second screen 

6 

transmitting graphic information, means for 

scanning a message to be transmitted to derive 

therefrom an electric signal irregularly assuming a succession of values responsive to the photographic density of the message at the point of 

scanning, means for substantially simultaneously 

scanning a camouflage message to derive a second 

electric signal irregularly assuming a succession 

of values depending upon the photographic density of the camouflage message at the point of 

scanning the second said electric signal being non- synchronous with the first with respect to the 

variations therein, a switch having two circuitclosing positions, means for causing said switch 

to assume one of its circuit-closing conditions 

when said first-mentioned electric signal assumes one value and the other of its circuit-closing con- ditions when the said first-mentioned signal as- sumes another of its values, a second switch having two circuit-closing conditions, and means for 

controlling said switch respansive to said second 

electric signal, a third switch, a control circuit 

for said third switch said circuit serving to close 

said switch when the first-mentioned two switches are in predetermined circuit-closing pasitions 

only, and means for transmitting a signal when 

said third switch is in closed condition. 

5. Means for secretly transmitting graphic information comprising a device for scanning a message to be transmitted and reproducing said 

message as a series of electric impulses of varying 

intensity, a second device for scanning a camou- flage message and reproducing the same as a series of electric impulses of varying intensity the 

impulses of said second series being non-synchro- nous with the impulses of the said first series, a relay connected under the control of said first 

device and arranged to be moved by each of said 

impulses to one of two positions, a second relay 

connected under the control of said second device 

and arranged to be moved by each of the impulses of said second series of said impulses to one of two positions, an electric circuit including 

said relays adapted to be closed only when predetermined combinations of closed positions in 

said relays occur simultaneously, and a transmitter connected under the control of said electric 

circuit so as to emit impulses only whenever said 

circuit is closed. 

wn.LIAM F'. FRIEDMAN. 

REFERENCES CITED 

The following references are of record in the 

file of this pa.tent: 

as a fourth series of electric impulses of varying 50 

intensity, a third relay connected under the con- trol of said third scranner and arranged to be 

moved by each of said impulses of said fourth 

series to one of two positions, a fourth relay 

connected under the control of said receiver and 

arranged to be moved by each of said impulses 65 UNITED STATES PATENTS 

of said third series to one of two positions, an electric circuit including parts of said relays and 

adapted to be closed only when there is instantaneously an impulse in either said third or said 60 fourth series but not in the other. and a recorder 

connected under the control of said circuit and 

arranged to be energized whenever said circuit 

is closed to record the original message. 

4. In an apparatus of the nature described for 65 

Number 

1,310,'719 

1,312,574 

1,657,366 

1,763,358 

1,848,839 

1,868,967 

2,300,664 

Name Date 

Vernam ------------ July 22, 1919 

Pierce ------------- Aug. 12, 1919 

Belin -------------- Jan. 24, 1928 

Jenkins ----------- June 10, 1930 

Ranger ------------- Mar. 8, 1932 

Cartier ------------ July 26, 1932 

Francis ------------- Nov. 3, 1942 
May 15, 1951 

"' f) xx 

N x x 

- x x 

... ~ lo !'t ... a J; ~ ~ II) 

~~~ 

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REF ID:A36245B 

W. F. FRIEDMAN 

FACSIMILE ENCIPHERING SYSTEM 

Filed March 6, 1943 

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