US2471473A - Transmission system - Google Patents

Description

May 31,- 1949 N. H. YOUNG, JR 2,471,473

TRANSMISSION SYSTEM Y original Filed Nov.' 1, 194s 4 Sheets-Sheet 1 A T TOP/MY May 311, 1949*. N.\ YOUNG, JR 2,471,473

TRANSMISSIONV SYSTEM` l original mea Nov. 1, 1943 Sheets-sheet 2 F @y Trim/G M u?? afm? TIME aoc/(ws Pyzsfs JI T TIPIVEY May 3l, 1949. N. H. YouNG,r JR

TRANSMISSION SYSTEM 4 Sheets-Sheet 5 Original Filed Nov. .1. 1943 May 3l, 1949, N. H. YoUNG, JR y 2,471,473

'TRANSMISSION SYSTEM n Original Filed Nov. 1, 1943 l 4 Sheets-Sheet 4 INVENToR. mM/1N H. mtu/v6, J.

, A TTORNE Y Patented May 31, 1949 TRANSMISSION SYSTEM Norman H. Young, Jr., Jackson Heights, N. Y.,

assignor to Federal Telephone 'and Radio Corporation, New York, N. Y., a corporation of Delaware Original application November 1, 1943, Serial No.

508,617, now Patent No.

tomber 10, 1946. Divld ed and this March 19, 1945, Serial No. 583,538

2,407,336, dated Sepapplication 8 Claims. (Cl. 177-380) l This invention relates to methods and means for transmitting intelligence, and more particuvlarly to a secret radio transmission system of the type `in which pulse signals are converted into intelligence signifying indications. I

'I'his is a division of my copending application for Methods and means for transmitting intelligence, Serial No. 508,617, tiled November 1, 1943; now U. S. Patent Number 2,407,336, dated Septem ber 10, 1946.

An object 'of this invention lis to provide a novel method and means for secret radio or other transmission of signal pulses, which provide a favorable signal-to-noise ratio and good resistance to interference, such as jamming.

A further object of this invention is to provide means for transmitting predeterminately timed synchronizing pulses and variably timed intellisence-signifying pulses. 1 Y

An additional object of this invention is the provision of an improved pulse-generating device for providing one set of continuously spaced synchronizing pulses and another selective set of intelligence signifying pulses variable in spacing from said synchronizing pulses.

Generally speaking, this invention may be dened as comprising the construction .and combinations recited in the annexed claims and illustrated in certain embodiments in the drawings accompanying and forming a. part of this application wherein:

Fig. 1 is a block circuit diagram of a preferred form of communication system in accordance with the present invention;

Fig. 2 is -an enlarged plan view of a detail of one of the elements of the communication system illustrated in Fig. 1;

Fig. 3 is a chart illustrating the time spacing between certain intelligence-signifying pulses and the synchronizing pulses in accordance with the present invention, together with their relationship to an amplifier blocking pulse;

Fig. 4 is a front plan view of a cathode ray screen illustrating the manner in which signals are reproduced according to a preferred form of this invention; o

Fig. 5 is a block circuit diagram of a modified form of a receiving system; l

Fig. 5A is a partial enlarged plan view of a modied form of pulse-generating apparatus to be used in connection With the receiving system illustrated in Fig. 5

Fig. 6 is a. transverse view partially in section, of

2 a partial circuit diagram o1' a, part of the pulse generating apparatus illustrated in Fig. 6;

Fig. 8 is a partial front elevation of the pulsegenerating apparatus illustrated in Fig. 6.

In the preferred and simplest form of the invention illustrated in Fig. 1, I propose to. use pulse-generating apparatus of generally known form, consisting of a keyboard I0 provided with suitable indicia designating various characters to be selectively produced, which controls the passage of light through a. rotatable drum I2 to a light-responsive cell or cells Il. Similar apparatus is already known in the art, for example, in the British patent to Creed and Company, 469,809, and also disclosed in the copending application of Edmond M. Deloraine, S. N. 415,554, filed October 18, 1941; now U. S. Patent Number 2,365,458, dated December 19, 1944. As is more fully explained in the aforesaid patent and copending application, the diierent keys of the keyboard III control the passage of light through various openings on the rotatable drum I2 to initiate action of the light-sensitive device which, in turn, through suitable apparatus is converted into usable pulses. In accordance with the present invention the drum I2, shown in more detail in Fig. 2, may be provided with one or more openings s `used to generate a series ofV regularly timed pulses used for synchronizing purposes. Each opening s is followed by laterally displaced additional openings indicated at A, B, C, D, E, F, G, by way of example, each one of these openings being spaced about the drum I2 a dliferent distance from the synchronizing opening s. In accordance with the present invention no control of light through the opening s is necessary since this will produce synchronizing pulses which are desired at all times that the apparatus is operated. However, suitable means are provided, such as key-controlled shutters, for controlling the passage of light through the remaining openings, at will. It will be seen that if light is permitted to pass through opening A, a pulse will be generated, and timed after the synchronizing pulse formed by the opening s with a predetermined spacing. If the opening B is exposed, another pulse at a diierent time from the synchronizing pulse will be generated, etc. It will therefore be apparent that according to the present invention various characters are designated by individual pulses which differ in timed relationship with the synchronizing pulse.

The synchronizing mais am: +1.., hmm-m ampliled as by amplifier I8 and transmitted by transmitter 20.

The receiver 22 will demodulate the signals and at its output will produce both the synchronizing pulses and the timed intelligence-signifying pulses. The receiver output may be amplified as through amplifier 24 and thence connected across the vertical plates of a, cathode ray tube 26. The receiver output is passed through another amplier 28 controlling a sweep generator 36 connected across the horizontal plates of the cathode ray tube. However, in order to properly reproduce a signal or a character in accordance with that transmitted, the sweep generator 30 should be keyed by the synchronizing pulses only. For this Purpose the output of the amplifier 28 is also directed to a suitable apparatus such as a biased multivibrator 32 whose output may then be passed through a pulse shaping circuit 34 to block the amplier 28. The timing of the biased multivibrator 32 is so arranged as to block the ampliier 28 upon the reception of a synchronizing pulse, and for a period substantially equal to the period between successive synchronizing pulses such intelligence-signifying pulses as may be impressed upon the amplifier 28 will not be effective to key the sweep generator, since the latter pulses all occur during this blocking period.

This operation may be more clearly understood from the diagram shown in Fig. 3. In the first place, the synchronizing pulses caused by the opening s in the pulse-generating device are shown at s" while, if it is assumed that the letter E is being transmitted, pulses properly spaced from the synchronizing pulses may appear at E'. Qther pulses shown merely by wayof example in order to indicate the general difference in timed relationship, are shown at G' and R. All intelligence signifying pulses will occur between successive synchronizing pulses s'. When a received synchronizing pulse s' passes through the amplifier 28, it not only initiates the actionv of the sweep generator 36 but also that of the biased multivibrator 32. The latter, can be so designed as to produce a single pulse bb of predetermined length indicated at Fig. 3. As shown in Fig. 3 this pulse can be made to extendrfrom the first of the synchronizing pulses s substan- ,tially up to the next synchronizingpulse, blocking the amplifier 26 for that entire period, and as a result none of the intelligence-signifying pulses will falsely key the sweep generator.

As shown in Fig. 4, the cathode ray tube 26 may be provided on its screen with a suitable scale 36 bearing in spaced relation the characters corresponding to the characters transmitted. When the sweep generator, as initiated by the synchronizingpulse, begins its `action to move the cathode ray beam/across the screen at a predetermined time, the vertical plates of the cathode ray tube will be energized by an intelligence signifying pulse whose position is so calibrated with the scale 36 as to pOint to the character originally. transmitted and lcorresponding to this time spacing. In Fig. 4, by way of example, I have` shown the pulse signal E appearing under the letter E" on the scale 36, and thus the operator can pick out this letter and similar letters so indicated in accordance with the spacing and timing of the. intelligence-signifyirig` pulses. 'I'he synchronizing pulse is also applied to the vvertical deflecting plates of the Ycathode ray tube but its position will be removed from the scale 26, being shown for example, at s" in Fig. 4.

In the form of invention described above, it has been assumed that the individual synchronizing pulses have the same parameters as the various intelligence-signifying pulses. It is known, however, that pulses may be distinguished by their parameters and if, for example, the synchronizing pulses are given a different parameter from the intelligence-signifying pulses, separation of such synchronizing pulses at the receiver may be more simply effected than in the system just described. In this case, the receiving system, shown by Way of example in Fig. 5, would consist of the receiver 22, amplier 24 and cathode ray tube 26 in the manner described above, but the output from the receiver 22 would also be passed through a pulse selector 38 prior to the amplier 28 controlling the sweep generator 36. If, for example, the synchronizing pulses were of greater amplitude than the intelligencesignifying pulses, as might be effected as seen in Fig. 5A, by a drum I2' having a synchronizing opening s1 of greater amplitude than openings A1 and B1, the resulting synchronizing pulses, as will be clear to those skilled in this art, would be of greater amplitude and could be clipped for the purposes of pulse selection. Of course, distinction could be made by reason of pulse '.'idth or shape, selecting circuits for which are known to the art. The modification of my system just described may provide simpler receiving apparatus but, on the other hand, slightly complicates the transmitting system.

In Figs. 6, 7 and 8, I have illustrated a novel type of device for the purpose of generating both synchronizing and intelligence-signifying pulses, and which may take the place of the light-sensitive type of pulse-generating device known to the art and used by way of example in the systems shown in Figs. 1 and 5. This device may consist of a small drum or cylinder 40 provided with a plurality of peripherally spaced radial openings in which are slidably mounted stop arms 42 which, therefore, will be angularly displaced about this drum. An arm 44 having an extension 46 is connected through a friction drive 48 to a rotating shaft 50 and will be normally free to rotate within the drum unless one of the various stop arms 42 is depressed, in which case the arm 44 will be held in xed angular position, as shown in Fig. 6. On the shaft 50 there also appears a rotating switch 52 having a conductive portion 54. An arm 56 holds a brush 66 in contact with the surface of the rotating device 52, and will therefore intermittently contact the conductive portion 54 thereof. A second brush 58 may be in continuous contact with the conductive portion 54 The brush 60 and arm 56 are pivotally mounted as by shaft 62 on the arm 44. It will thus be seen that when none of the stops 42 are depressed, the arm 44 rotates with the rotating t switch 52 and there will be no relative movement between the brush 60 and conductive portion 54. However, when thearm 44 is held stationary in various angular positions, the clutch 48 permits relative movement between the arm and the rotating switch 52 and intermittent contact between the brush 66 and the conductive portion 54. Rotating on the shaft 50 is a second rotary switch 64 having a conductive portion 66 making intermittent contact with a fixed brush 68. A second brush .1.0 is in contact with conductive portion '66. A motor 12 may be used to drive the shaft 50.

If a source of power such as a battery 14 is connected to the brush 68 it will be seen that from the brush 10 will appear, at a frequency des l termined by the speed of the motor 12, a series of positive pulses have a predetermined time spacing. If the source of power 14 is also connected through a brush 15 to the rotating contact arm 44, no pulses willappear at the brush 58 when the contact arm is free to rotate with the rotary switch 52, but when the contact arm 44 is heldin a ilxed angular position upon the depression of one of the stops 42, the contacting of the brush 60 with the conductive portion 54 due to the relative rotation at this time will produce a series of pulses bearing a .definite time relation to the pulses produced by the device 64, such time relation depending upon the angular position at which the contact arm 44 is stopped. In accordance with the present invention and as previously described, the different intelligence-signifying pulses are characterized by different spacing from these synchronizing pulses and ,accordingly, if the stops 42 are selectively depressed in accordance with the signal or character desired, the aforedescribed device will produce this selected time variation in the manner desired. Since the pulses produced by this device will be of a relatively long duration and will be relatively coarse, the output therefrom may be shaped through a suitable pulse-shaping device 16 before used to modulate the carrier for transmitting purposes.

In Figs. 6 and 8, I have shown, by way of example, means by which the various stops 42 may be selectively controlled, as by a keyboard. The stop arms 42 are preferably biased to an outward position by any suitable means such as springs, while cam' members 18 are utilized to press the various stops inwardly against the action of such retracting springs. The cams 16 are mounted on individual rockershafts 19 which, in turn, may be rotated by longitudinally extending rods 80, acting through individual rocker arms 8|. The longitudinally extending rods 80 are moved upwardly upon a depression of keys 82 of the keyboard which, as is common in the art, will bear suitable identifying indicia. Upward movement of the rods 80 rotates the individual shafts 19 in a direction to press the selected cams 18 against the individual stop members 42. The assembly may be mounted in a suitable frame, the rocker shafts 19 being pivotally supported at either end by rings 84 and 86 supported within a suitable mounting frame 88. As will be seen in Fig. 8, in which some of the connections between keys and rocker shafts have been illustrated by way of illustration, while others have been omitted to prevent complicating and confusing the drawing, the vertical rods 80 with the individual rocker arms will be longitudinally spaced from one another -comparatively to the positions on the controlling keys of the keyboard. In these figures I have indicated further, by way of example, the depression of the key 32 corresponding to the letter E, resulting in an upward movement of the rod 80 and a clock-wise rotation of the rocker arm 8| and shaft 19', with a resulting downward movement of the cam 18 against the now depressed stop member 42'.

While in Figs, 7 and 8 I have illustrated for the purpose of showing an operable example, various links, cams, vrods and levers for suitably operating the stop arms 42 from a keyboard, it is contemplated that other equivalent means for Huhv-n-MM\ w..." 1.... .-.....1

fulfill the objects primarily stated. While the timing of the synchronizing pulses :and the following intelligence signifying pulses can be varied in accordance with the desired apparatus and within limits which will be clear to those skilled in this art. For-example, in order to more clearly distinguish at the receiver between synchronizing and intelligence-signifying pulses, the two sets of pulses could be transmitted at diilerent frequencies as disclosed, for example in my copendlng application S. N. 457,407, led September 5, 1942, or the two may be distinguished by utilizing one as an amplitude modulator and another as a frequency modulator, with comparable discriminating apparatus at the receiver. Both of these methods would avoid all possibility of error due to keying ol the synchronizing apparatus by the intelligence-signifying pulses, which might occur for a brief period, although this conditionwould soon automatically correct itself due to the regularity of the synchronizing pulses and the irregularity between different sets of intelligence signifying pulses. Obviously the system isv applicable to direct or carrier wire transmission as well as radio transmission. Accordingly, while I have described above the principles of my invention in connection with certain specific apparatus and particular modiications. thereof, it is to be clearly understood that this description is made only by way of example Vand not as a limitation on the scope of my invention' as set forth in the objects and the accompanying claims.

I claim:

1. An intelligence transmission system comprising means generating a series of synchronizing pulses of a predetermined frequency, means generating a series of sets of intelligence-signi-- fying pulses of the same frequency as said synchronizing pulses, the pulses for each intelligence-signifying character occurring between successive synchronizing pulses, and the pulses of each set being distinguishedfrom the pulses of another set by a different time spacing from the synchronizing pulses, and controllable means for varying said time spacing at will.

2. A transmission system according to claim l, in which both pulse-generating means are arranged to produce individual pulses having substantially identical parameters.

3. A transmission system according to claim 1, in which the second-named pulse-generating means includes a rotary switch device having a rotating contacting surface provided with a predetermined conductive portion, a contactor urged against said surface, frictional means normally rotating said contactor with said rotary switch device, and controllable means holding said contactor in various fixed angular positions depending on the intelligence to be transmitted, whereby the time relationship between said contactor and said rotary switch device may be varied according to the intelligence character to be transmitted.

4. A transmission system according to claim 1, in which the second-named pulse-generating means includes a rotary switch device having a rotating conductive portion, a contactor biased to a position in contact relationship with said conductive portion during rotation thereof, frictional means normally rotating said contactor with said rotary switch device, a plurality of and selective means for movingsald stop arms inwardly in the/path of said contactor to hold it in selectiveV angular positions, whereby the time relationship between said contactor and said rotary switch device may be varied *according to theintelligence character to be transmitted. c

5. A transmission system according to claim 1, in which the first-named pulse-generating means includes a rotary switch device having a rotating contacting surface provided with a predetermined conductive portion, and a fixed contactor engageable with said surface and contacting said conductive portion at predetermined intervals as the switch device rotates, and inA which the second-named pulse-generating means includes a second rotary switch device having a rotating contacting surface provided with a predetermined conductive portion, a contactor urged against said surface, frictional means normally rotating said contactor with said second rotary switch device, and controllable means holding saidy contactor in various fixed angular positions depending on the intelligence to be transmitted, whereby the time relationship between the contacting of the second contactor with the second rotary switch device, may be varied relatively to the contacting of the first xed contactor with the first rotary switch device according to the intelligence character to be transmitted, andmeans rotating said rotary switch devices.

6. A transmission system according to claim 1, in which the first-named pulse-generating means includes a rotary switch device having a rotating contacting surface provided with a predetermined conductive portion, and a fixed contactor engageable with said surface and contacting said conductive portion at predetermined intervals as the switch device rotates, and in which the second-named pulse-generating means includes a second rotary switch device having a rotating contacting surface provided with a predetermined conductive portion, a contactor urged against said surface, frictional means normally rotating said contactor with said second rotary switch device, a .ring surrounding the contactor f said second rotary switch device, a plurality of radially said stop arms outwardly, and selective means for l the second contactor to hold it in the selective fixed angular position, `whereby the timerelationship between the contacting of the second contactor with the second rotary switch device may be varied relatively to the contacting of the first fixed contactor with the first rotary switch device, according to the intelligence character to be transmitted, and means rotating said rotary switch devices.

7. A method of intelligence-transmission comprising generating a series of pulses of predetermined frequency, generating a second series of sets of pulses of the same frequency, each pulse of said second series occurring between successive pulses of the rst series and differing from the pulses of the other sets by a different time dis-v placement from the pulses of the rst series, whereby each pulse of each set of said lsecond series may represent a character to be trans; mitted, and the further step of varying said time displacement at will.

8. A transmission system comprising means for generating a series of synchronizing pulses, a series of devices each corresponding with a distinct intelligence-signifying character, means responsive to selective operation of one of said devices for generating a set of intelligence-significant pulses, means responsive to a succeeding selective operation of said devices for generating a further set of intelligence-significant pulses, the intelligence-signifying character of each set of pulses being dependent upon the timing of each pulse of said each set of pulses with respect to said synchronizing pulses, and controllable means for varying said timing at will.

NORMAN H. YOUNG, JR.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,770,485 Jipp July 15, 1930 2,053,091 Lemmon Sept. 1, 1936 2,104,544 Lemmon et al. Jan. 4, 1938 2,125,491 Dean- Aug. 2, 1938 2,403,890 Johnson July 9, 1946 2,407,336 Young Sept. 10, 1946

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