A. V. HAEFF ET AL FULSE TRANSMISSION SYSTEM

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Document Number (FOIA) /ESDN (CREST): 
CIA-RDP81-00120R000100050005-7
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RIFPUB
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K
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9
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December 20, 2016
Document Release Date: 
July 26, 2000
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5
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Publication Date: 
July 24, 1951
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CONT
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Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 July 24, 1951 A. V. HAEFF ET AL 2,555 61,363 PULSE TRANSMISSION SYSTEM LOCAL OSCILLATOR 17- ATTENUATORH.IMIXER NO.2.~{I~Q FNR E[ TECTORNO 3n CONTROL CONTROL 1DELAYCONTR TUBE RECTIFIER AMPLIFIER 40 41 42 34 51 ENABLING S MEMORY ERROR CATHODE SIGNAL FOLLOWER STORAGE SQUELCH TRIODE 56 O!/TPVT FROM D/Pfl . NT/AL //oEO i9MpL,P/ER /6 e,/?. /} 1NVEN?ORS ANDREW V. HAEFF FRANKLIN H. HARRIS BY TORAGE 3 Sheets-Sheet 1 b2 MEMORY TTRIGGER .v moaaL 4roR ERROR SIGNAL AMPLIFIER Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 Approved For Release 2007/09/21: CIA-RDP81-00120R000100050005-7 lftwrl~ July 24, 1951 A. V. HAEFF ET AL PULSE TRANSMISSION SYSTEM 2,561,363 INVENTORS ANDREW V. HAEFF FRANKLIN H. HARRIS BY Approved For Release 2007/09/21: CIA-RDP81-00120R000100050005-7 Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 July 24, 1951 A- FROM MULTIVIB, 50 TOORIO OF TUBE 53 B- FROM MOLT,v,8. 9/ TO yIt/0 OF 77/BE S3'2 C- COMB/NATION OF A AND B AT rrR//,O C OF re/8E .5'J FROM MOL T/V/B. SO TH.POUd /1 70 TO TUBE S5 F- ?e,a OF TUBE SS (Cogia,NATION OF O 44'O E/ , SATU RATI O N CUT OFF - ANDREW V. HAEFFPUBS FRANKLIN H. HARRIS BY 2,561,363 Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 Patented July 24, 1951 2,561,3163 UNITED STATES PATENT OFFICE 2,561,363 PULSE TRANSMISSION SYSTEM Andrew V. Haeff, Washington, D. C., and Franklin H. Harris, Accokeek, Md. Application January 16, 1946, Serial No. 641,548 13 Claims. (Ci. 250-15) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) i 2 This invention relates to devices used to render which perform these functions, such as those enermy radio echo object detecting and ranging described in greater detail in the copending ap- equipment ineffective. plication of Andrew V. Haeff and Franklin H. One of the important special applications of Harris, entitled: A Synchronizing System, Serial radio echo object detecting and ranging equip- 5 Number 641,363 filed January 15, 1948, normally ment is its use for the control of gun fire. In will utilize each received pulse from the enemy such applications the radio echo equipment is radio location equipment to actuate an interfer- designed to determine the range and bearing of ing pulse delayed so that it will include the next target objects with greater accuracy than is nor- following echo pulse reflected from the target mally possible with radio echo location equip- 10 object. Synchronization is maintained by gen- ment intended for detection and search purposes erating error signals when discrepancies arise, only. and using these error signals to alter the delay. Efforts to render enemy radio echo location The effectiveness of these timing circuits is equipment ineffective commonly consist of trans- impaired if, because of atmospheric conditions mitting a suitably modulated interfering signal 15 or other reasons, one or more pulses from the which either saturates one or more stages of the enemy radio echo location equipment is not re- radio echo location receiver or renders the visual ceived. The aim of the present invention is to presentation unintelligible. For the latter pur- obviate this impairment. pose modulation with a form of random signal It is accordingly one object of this invention containing a broad spectrum of frequencies up to 20 to continue the actuating of an interfering trans- several megacycles, known as noise modulation, mitter at an established pulse repetition rate has been found most effective. when the normal actuating signal is temporarily The interfering signal must be tuned to or ap- interrupted. proximately to the carrier frequency of the en- Another object of this inventuion is to provide emy radio echo location equipment. To be effec- 25 a correction to the synchronizing circuits of an tive, the interfering signal must be many decibels interfering transmitter when the pulse repetition larger than the echo signal at the enemy radio rate of the enemy radio echo location equipment echo location receiver. Also, the interfering decreases. transmitter should be capable of being modulated A further object of this invention is to provide with a signal containing relatively high frequen- 30 a means for returning' control to the basic syn- cies. These three requisites therefore create the chronizing circuits when a large change occurs in need for an interfering transmitter, tunable over the pulse repetition rate of the enemy radio echo a broad range, capable of modulation up to sev- location equipment. eral megacycles, and capable of delivering a large Other objects and features of the present in- amount of power spread over its frequency spec- 35 vention will become apparent upon a careful con- trum. If the interfering signal is to be contin- sideration of the following detailed description uous, the design of such a transmitter involves when taken together with the accompanying the use of special power tubes which are not drawings, in which: readily available. Fig. 1 is a block diagram of the interference An alternative method is to transmit the inter- 40 transmitting system of which this invention is a fering signal in suitably timed pulses. Such a part; method, described in greater detail in the copend- Fig. 2 is a block diagram of the basic circuits ing application of Andrew V. Haeff, Serial Num- used ;in timing the pulses and the pertinent cir- ber 641,549, filed January 16, 1946, entitled: cuits of the invention; Pulse Generation System permits substantial 43 Fig. 3, partly in schematic form, shows the peak power output from tubes with low average basic timing circuits, the circuits which continue power capacities. Its use is based on the premise operation during temporary interruptions of the that for the protection of individual targets from received signals, and the circuits which provide, enemy fire control radio echo location equipments the correction to the synchronizing circuits when it is sufficient ' to generate interfering signals 50 the pulse repetition rate changes; which will be received by these equipments only Fig. 4 is a diagram, partly schematic, of the in the immediate proximity of the echo signal, circuits which return control to the basic syn- so as to render impossible ascertainment of the chronizing circuits when a large change occurs exact position of the target object. in the pulse repetition rate; and With this alternative method, timing circuits 55 Fig. 5 shows a series of wave shapes useful in are required which will cause an interference explaining the various circuits which provide the pulse to be transmitted at such times that they correction. will include echo pulses and which will maintain The interference transmitting system of which this synchronization regardless of changes in the the present invention is a part, and which is de- enemy. pulse repetition rate. Timing circuits 00 scribed in detail in the Haeff application supra, Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 3 receives radio pulses of enemy origin and utilizes them to actuate pulses after a suitable interval which in turn actuate a transmitter. In order that the output of transmitter will not reactuate the system, means are provided whereby a por- tion of the transmitter output neutralizes the transmitter signal received by the receiver antenna. Specifically, and in accordance with the ar- rangement shown in Fig. 1, the pulses trans- mitted by the enemy radio are received by antenna 10 of a directional type, amplified by preselector II, and converted to signals of-an intermediate frequency by beating with the out- put of local oscillator 15 in mixer 12. These intermediate frequency signals then are amplified In intermediate frequency amplifier section 13, demodulated in detector 14, and further amplified in differential amplifier and video amplifier 16, the output of which is applied to cathode ray indicator tube IT and to the delay pulser 22. For each trigger pulse received from the video amplifier I6, the delay pulser 22 applies an actu- ating pulse to modulator 25 after a suitable delay. Modulator 25 in turn actuates transmitter 24, the output of which Is radiated through a separate directional antenna 23. The delay occasioned by delay pulser 22 is such that the actuating pulse from the delay pulser overlaps the next succeed- ing pulse received from the enemy. The cathode ray indicator tube 17 and its associated circuits are used in adjusting the pulser 22 to the enemy pulse repetition rate. A small portion of the output of transmitter 24 is fed through attenuator 18 to mixer 16 where it is converted to the intermediate frequency by beating with the output of local oscillator 15. This signal is amplified in intermediate frequency amplifier section 20, demodulated in detector 21 and applied to differential amplifier 18. Dif- ferential amplifier 16 is arranged, in a manner described in the Haeff application supra, so that the signal originating in leakage radiation cou- pling between the receiving and transmitting antennas 10 and 23 respectively and applied from detector 14 is neutralized by the signal applied from detector 21. Accordingly, when the channel containing detector 21 is operative, only the pulses received from the enemy radar and a small residue of the interference pulses are passed to delay pulser 22 and cathode ray tube IT. The interrelation of the pertinent circuits con- tained in the delay pulser is shown in Fig. 2. The timing and duration of the interference pulse is determined in the channel comprising a series of timing pulse generators shown in this embodi- ment as multivibrators 31, 84, and 35. Multi- vibrator 31 is a one-shot multivibrator the period of which is controlled both mechanically (by ad- justing the resistance or capacitance of the grid circuit of the normally conducting tube) and by the voltage applied from the control tube 49. Multivibrators 34 and 35 are also one-shot multi- vibrators the periods of which may be adjusted. Multivibrator 81 Is triggered by the pulse signal received from the enemy, which is applied at input 80, and the trailing edge of the output of this multivibrator triggers multivibrator K. The trailing edge of the output of multivibrator 34 in turn triggers multivibrator 85. The combined periods of multivibrators 31 and 34 determine the time elapsing between the reception of the first pulse from the enemy and the start of the interference pulse which is to obscure the echo from the next succeeding pulse from the enemy. 4 Multivibrator 85 determines the duration of the interference pulse. Multivibrator 89, which is another one-shot multivibrator with an adjustable period, is used 6 in the automatic delay control circuits presently to be described. This multivibrator is also trig- gered by the trailing edge of the output from multivibrator 34. The total of the periods of multivibrators 31, 34, and 39 is made equal to 10 the interval between pulses received from the enemy. The timing in the system as above described would be adequate if no changes occurred in the pulse repetition rate of the enemy radio echo 15 location equipment. For the possibility that such changes will occur, it is desirable to provide means whereby the system automatically adjusts itself to such changes. The mixing network 38, auto- matic delay control amplifier 42, the delay control 20 rectifier 41 and the control tube 40 perform this function. Positive pulses of equal amplitude are applied from multivibrators 31, 34, and 39 to mix- ing network 88. Since the combined periods of these three multivibrators are equal to the in- 25 terval between enemy pulses at the initial pulse repetition frequency, the output of the mixing network is a steady direct current voltage as long as the enemy pulse repetition frequency remains constant. If, however, the enemy pulse repeti- 80 tion frequency is increased, part of the output of multivibrator 39 will overlap the start of the posi- tive pulse from multivibrator 81, and positive pulses will appear in the output of mixing network 38. Similarly, if the enemy pulse repetition rate 35 Is decreased, negative pulses will appear in the output of the mixing network. The automatic delay control rectifier 41 operates to convert these positive or negative pulses into steady sig- nals which are applied to the grid of delay con- 40 trol tube 40. The period of multivibrator 81 (see Fig. 3) is determined in part by the potential to which the grid of its normally conducting tube is returned. This potential is determined by the delay control 45 tube in such a way that the period of multivi- brator 31 is decreased if positive pulses are ap- plied to automatic delay control amplifier 42 and, conversely, is increased if negative pulses are ap- plied to automatic delay control amplifier 42. 60 This action tends to keep the system synchro- nized with the enemy pulse repetition rate. The timing and synchronizing system which has been described above, and which is described in greater detail in the Haeff and Harris appli- 55 cation supra, will be adequate provided there is no interruption, due to atmospheric or other con- ditions, in the reception of signals from the enemy radio echo location equipment. When such in- terruptions do occur, as has been mentioned pre- 60 viously, the effectiveness of the system will be im- paired. The circuits represented by the remain- ing blocks in the Fig. 2 circuit representation are to prevent this impairment. If the pulse repetition rate of the enemy equip- 65 ment remains the same, and if adequate recep- tion of signals from the enemy is somehow inter- rupted, it is necessary that the system continue to be triggered at the proper intervals during the TO interruption. The trailing edge of the output from multivibrator 39 coincides in time with the reception of the next succeeding signal from the enemy for the established pulse repetition rate. Consequently, the trailing edge of the output from 7 mlultivibr tqr 38 14 used to actuate the memory Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 Nftwol trigger tube 52 which in turn applies the required trigger pulse to the input of multivibrator 81. It is necessary that the memory trigger tube 52 be operative only for a short interval after sig- nals from the enemy equipment cease entirely; 5 otherwise, the memory feed back channel would continue the system in operation for an indefi- nite period. Consequently, memory trigger tube 52 must be supplied with an enabling voltage which is present only while and immediately after 10 the enemy equipment is in operation. Multivi- brator 50 is a one shot multivibrator triggered by the signals received from the enemy at input 80. The output pulses from multivibrator 50 are fil- tered in the enabling voltage holding circuit 51 15 to provide the required enabling voltage for mem- ory trigger circuit 52. If, while the memory circuit is in operation, the enemy pulse repetition rate is increased, the au- tomatic delay control circuits will operate in the 20 normal manner to return the system to synchro- nization, since the next received signal from the enemy will trigger multivibrator 31 before the memory trigger pulse from memory trigger tube 52 is generated. When the memory trigger pulse 25 is generated, it will be applied to multivibrator 31 at a time in the cycle of the latter when it will have no effect. If, however, the enemy pulse repetition rate decreases while the memory circuit is in opera- so tion, the memory circuit, as described above, would trigger the system before the next suc- ceeding signal from the enemy was received, and accordingly, the automatic delay control circuits would be prevented from maintaining synchro- 36 nization. Consequently, when this situation arises, error signals must be applied to the mixing network 38 from some adjunct of the memory circuit itself. Moreover, the adjunct must dis- tinguish between enemy signals arriving late and 40 enemy signals not arriving at all. Multivibrator 31 which is activated by either the enemy signal or the memory circuit, and multivibrator 50 which is activated by the enemy signal only, both apply signals to the memory cathode follower 53. If these signals coincide, no error signal is gener- ated; however, if the signal from multivibra- tor 31 arrives first, an error signal is generated which is stored in a capacitor resistor network 54 having a suitable time-constant. Then, if the enemy signal only is late, when this signal is re- ceived, the output from multivibrator 50 applies the error signal remaining in the storage network 54 to the error signal amplifier 55. From the error signal amplifier 55 it is applied as a nega- tive pulse to the mixing network 38, actuating the automatic delay control circuits. If, however, no enemy signal corresponding to the cycle un- der consideration arrives, the stored error sig- nal expires according to the time-constant char- acteristics of network 54, and the memory circuits operate normally without actuating the auto- matic delay control. It has been found that with the memory cir- cuits in operation, the synchronizing circuits are not as responsive to sudden changes in the enemy pulse repetition rate as they are without the memory circuits in operation. In particular, if the enemy pulse repetition rate is switched to a significantly different value, there is the possi- bility that the system will stabilize itself in such a way that only some submultiple of the enemy pulses Is covered. For this possibility, means are provided to disable the memory circuits when enemy signals are not being covered by the in- fig 6 terfering pulses. A signal corresponding to the interfering pulse from multivibrator 35 and the signal received from the enemy are both applied to squelch triode 66. If the latter signal occurs during the interval of the former, there is no output from the squelch triode 56. If, however, an enemy signal does not occur during the in- terval of the former, it causes the squelch triode 56 to apply a short pulse to multivibrator 50. This short pulse applied to multivibrator 60 pre- vents this multivibrator from being actuated by the enemy signals. When multivibrator 50 is not actuated, the enabling voltage holding cir- cuit 51 does not provide the enabling voltage to the. memory circuit. Accordingly, the memory circuits are rendered inoperative and the ad- justment in the timing is made directly by the automatic delay control circuits. For a more detailed description of the memory circuit and some of its associated circuits, refer- ence is now made to Fig. 3. Multivibrator 31 is triggered by means of a trigger tube, not shown, the signal from which is applied at terminal TO. The trailing edge of the output from multivi- brator 31 in turn triggers multivibrator 34, and the trailing edge of the output from multivi- brator 34 triggers multivibrator 39. A negative pulse is obtained from the cathode terminals 71 of this one shot cathode coupled multivibrator, which pulse is differentiated by capacitor 12 and resistor 73 for application to the grid of the memory trigger tube 52. Switch 15 determines whether or not the memory circuits are to be operative. When switch 15 Is open, the cathode of memory trig- ger tube 52 is returned to the positive side of the power supply, and the tube remains non-con- ducting regardless of signals applied to the grid. When switch 75 is closed, the cathode potential is determined by the voltage divider comprising resistor 14 and resistor 76. The potential deter- mined by this voltage divider is sufficient to hold the tube cut off in spite of signals applied to its grid from the differentiated output; of multivi- brator 39, unless a positive grid bias is obtained from the enabling voltage holding cathode fol- lower 51. If a positive grid bias is obtained from the enabling voltage holding cathode follower 51, the short positive pulse occassioned in the dif- ferentiator circuit by the trailing edge of the out- put of multivibrator 39 causes memory trigger tube 52 to be momentarily conducting. Memory trigger tube 52 has a common plate load resistor with the normally non-conducting tube of mul- tivibrator 31. Accordingly, when the former tube is rendered conducting, multivibrator 31 is actuated according to well known multivibrator principles, and the system is maintained in op- eration even if for some reason the signal ex- pected from the enemy radio echo location equip- ment is not received. The enabling voltage holding cathode follower 5I maintains an enabling grid bias for the mem- ory trigger tube for an interval long enough to permit the memory channel to operate through short interruptions in the reception of enemy signals, but not to operate indefinitely. This cathode follower is actuated by multivibrator 59 which is in turn actuated by trigger tube 17. Sig- nal pulses of positive polarity received from the enemy radio echo location equipment are applied to the grid of trigger tube 77. The cathode po- tential and thus the threshold sensitivity of tube 77 is determined by the position of the tap on potentiometer 18. Tube 17 has the same plate Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 9,ee1,808 . 7 load resistor as the normally non-conducting tube of multivibrator 60; consequently, this mul- tivibrator is actuated when tube 11 is rendered conducting by the enemy signals. A positive pulse is taken from the plate of the 6 normally conducting tube of multivibrator 50 and applied through a coupling network com- prising capacitor 79 and resistor 80 to the grid of enabling voltage holding cathode follower 51. The load of this cathode follower, comprising re- 10 sistor 81 and capacitor 82 in shunt, filters the positive pulse output, and a suitable direct cur- rent voltage is applied as bias from the cathode of tube 51 to the grid of memory trigger tube 52. The period for which this bias is retained after 16 enemy signals are no longer received is deter- mined by the time constant of the circuit com- prising resistor 81 and capacitor 82. 8 signal on the grid of- tube 55 is shown as wave- form F on Fig. 5. The cathode of tube 55 is maintained at a potential determined by the voltage divider com- prising resistors 98 and 94. As will be apparent from Fig. 5 F this potential is such that tube 55 Is held cut off except when the stored error signal and the pulse from multivibrator 50 operate in combination to raise the potential of the grid. Thus the tube is not rendered conducting if the enemy signal is received when it is expected and is not rendered conducting if the enemy signal is not received at all, but is rendered conducting if the enemy signal is received late. When tube 55 conducts, a negative pulse is obtained from its plate and applied to the mix- ing network 88 which actuates the automatic de- lay control circuits in the manner described in tion to the automatic delay control circuits when 20, For a more detailed description of the circuits the enemy pulse repetition rate decreases, two which return control to the automatic delay con- signals are applied to the memory cathode fol- trol circuits when the interfering pulse is found lower 53. to be not covering the echo signal effectively, re- A negative pulse is obtained from the normally ference is now made to Fig. 4. non-conducting tube of multivibrator 50 and 25 Short positive pulses coincident with the re- applied through capacitor 88 and resistor 89 to ception of enemy signals are applied from input the grid of tube 53. This signal is shown as wave- 80 to the grid of the squelch tube 56. Negative form A on Fig. 5 and its leading edge coincides pulses are also applied to this grid from the nor- with the reception of the enemy signal. Also, a mally non-conducting tube of multivibrator 85 positive pulse is obtained from the plate of the 80 through capacitor I01 and resistor 102. The lat- normally conducting tube of multivibrator 81, is ter negative pulses coincide in time with the differentiated by capacitor 85 and resistor 86, and interference pulses; consequently, when the is applied through resistor 87 to the grid of tube enemy signals are being properly included the 53. This signal is shown as waveform B on Fig- positive pulses from input 30 occur within the ure 5, and the leading edge of the positive pulse 85 negative pulses from multivibrator 35. corresponds to the time of triggering the system, The cathode potential of tube 56 is determined either by the enemy signal or by the memory by the voltage divider comprising resistors 103 circuit. and 104. This potential is such that the tube The combination of these two signals is shown remains cut off while no signal is applied to its as waveform C in Fig. 5. When the system is 40 grid and while the positive pulses from input 80 properly synchronized, the two leading edges are offset by the negative pulses from multivibra- coincide (as is shown in the first two cycles of tor 85. If, however, the received signals are not waveform C), and no significant positive signal is properly included, the two signals to the grid of applied to the grid of tube 53. If, however, the tube 56 arrive separately; and the positive pulses enemy signal is delayed or is not received, the 45 from input 80 render the tube conducting. positive pulse occasioned by the leading edge of When tube 56 conducts, a negative pulse is the output from multivibrator 31 does appear as applied from its plate through the coupling net- a positive signal (as is shown in the third cycle work comprising capacitor 105 and resistor 106 to of waveform C). the grid of the normally nonconducting tube of The cathode of tube 58 is connected to ground 50 multivibrator 50. This pulse arrives simul- through resistor 91 and resistor 80. Resistor 91 taneously with the trigger signal from trigger is a large resistor; consequently, in the quiescent tube 11 and prevents the multivibrator from being condition very little current flows through the actuated. When the multivibrator is not ac- tube. When a positive signal such as that shown tuated, the enabling voltage holding cathode fol- for the third cycle of waveform C is applied to 55 lower does not maintain an enabling voltage for the grid of tube 53, a substantial increase in cur- the memory trigger tube 52; and, accordingly rent occurs and capacitor 92 charges according the memory channel is inoperative. With the to a relatively short time constant. At the ter- memory channel inoperative, the automatic delay mination of this signal, the voltage developed control, circuits assume full control of the tim- across capacitor 92 is sufficient to cut tube 53 off; 60 ing. consequently the capacitor discharges according Although only a certain and specific embodi- to a much larger time constant. The voltage at ment of the invention has been shown and de- the cathode of tube 58 (the high potential side scribed, we are fully aware of the many modi- of the storage network comprising resistor 91 and flcations thereof. Therefore this invention is not capacitor 92) is shown as waveform D on Fig. 5, 65 to be limited except insofar as is necessitated The higher voltage observed for the third cycle by the spirit of the prior art and the scope of is, in effect, the error signal, and it is applied as the claims. enabling bias to the grid of the error signal am- In the appended claims the words "received plifler tube 65. pulse" are construed to mean any pertinent ac- A positive pulse is obtained from the plate of the 70 tuating signal, and the words "transmitted normally conducting tube of multivibrator 50 if pulse" are construed to mean any pertinent out- and when the enemy signal arrives. This pulse, put signal. which is shown as waveform E on Fig. 5, is ap- The invention described herein may be manu- plied through capacitor 79 and the storage net- factured and used by or for the Government of work to the grid of tube 55 also. The composite 76 the United States of America for governmental Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 f1,a111,$e8 9 Durposes without the payment of any royalties terval; a second one shotOmultivibrator initiated thereon or therefor. into operation by the output of the delay means. What is claimed is: the second one shot multivibrator and the delay 1. A method of recurrently transmitting pulses means in combination establishing the expected in dependency on a series of recurrent received interval between successive received pulses; pulses comprising the steps of receiving the re- vacuum tube means connected to the capacitor current pulses, initiating a timing period on re- means operative in response to the enabling volt- ceipt of a pulse, terminating the timing period age to reinitiate operation of the delay means in before the receipt of the next pulse, transmitting coincidence with the trailing edge of the output a pulse signal responsively to the termination of 10 of the second one shot multivibrator, the vacuum the timing period, recurrently generating a series tube means being rendered capable of operation of timing pulses at the average recurrence period by the enabling voltage. of a preceding number of received pulses follow- 6. A method of generating an error signal ing each received pulse by the same timing period, when the repetition rate of a first series of and initiating transmission of a periodic pulse in 1s periodic pulses decreases but not when pulses of response to a timing pulse in the event of failure the first series of pulses are omitted, which com- to receive a recurrent pulse. prises the steps of generating separately second 2. Apparatus for receiving periodic pulses and periodic pulses which are initially coincident transmitting other periodic pulses in response to with the first pulses, of polarity opposite to that the received pulses comprising time delay means I0 of the first pulses, and initially at the recurrence becoming operative responsively to a received rate of a preceding number of the first pulses; pulse, pulse transmitter means initiated into op- and generating an output error signal when eration after a time delay by the delay means, pulses of the first and second series both occur timing pulse generator means operative to supply but not simultaneously. timing pulses at the average recurrence rate of a u 7. A method of generating an error signal preceding number of received periodic pulses, and when the repetition rate of a first pulsed signal means responsive to the timing pulse generator decreases but not when pulses of this first pulsed means operative to initiate operation of the time signal are omitted, which comprises the steps of delay means in the event of brief interruption in generating separately a second pulsed signal the reception of periodic pulses. '0 which is initially coincident with the first signal, 3. Apparatus for receiving periodic Pulses and of polarity opposite to that of the first signal, and transmitting other periodic pulses in response to having the initial repetition rate of the first sig- the received pulses comprising time delay means nal; mixing the first signal and the second signal operative responsively to a received pulse, pulse to neutralize the signals when corresponding transmitter means initiated into operation after SS pulses of both signals occur simultaneously and a time delay by the delay means, pulse generating to form a third signal when it pulse of the first means initiated into operation by the output of signal occurs later than the corresponding pulse the delay means, the pulse generating means and of the second signal or does not occur; storing the delay means in combination establishing the the third signal for a suitable period; and apply- expected interval between successive received 40 ing the third signal as an error signal if and when of the first pulsed signal occurs within pulses; and means responsive to the trailing edge a that pulse period. of the output of the pulse generating means which reinitiates operation of the time delay 8. A means for obtaining error signals when means. the repetition rate of a first pulsed signal de- 4. Apparatus for receiving periodic pulses and 45 creases but not when random pulses of this first transmitting other periodic pulses in response to signal are omitted, which comprises; means gen- the received Pulses comprising time delay means erating a second pulsed signal nitially coinci- operative responsively to a received pulse, pulse dent with the first pulsed signal, said second transmitter means initiated into operation after signal being of polarity opposite to that of the a time delay by the delay means, a first pulse s0 first signal and having the initial repetition rate generating means initiated into operation by the of the first signal; means mixing the first signal received pulses; means converting the output of and the second signal to neutralize the second the first pulse generator means into a direct cur- signal when corresponding pulses of both sig- rent enabling voltage; capacitor means retain1jig nals occur simultaneously and to form a third the enabling voltage for a holding interval; a s6 signal when a pulse of the first signal occurs later second pulse generating means initiated into op- than the corresponding pulse of the second sig- eration by the delay means, the second pulse gen- nal or does not occur; means storing the signal erating means and the delay means in combina- for a suitable interval; and means applying the tion establishing the expected interval between third signal as an error signal if and when a successive received pulses; and means reinitiating 60 pulse of the first signal occurs within the interval. the delay means into operation from the trailing 9. A means for obtaining error signals when edge of the output of the second pulse generating the repetition rate of a negative pulsed signal de- means, the reinitiating means being rendered creases but not when random pulses of this nega- operative by the enabling voltage. tive signal are omitted, which comprises; means 5. Apparatus for receiving periodic pulses and generating separately a positive pulsed signal transmitting other periodic pulses in response to which is initially coincident with and has the the received pulses comprising, time delay means initial repetition rate of the negative signal; operative responsively to a received pulse; pulse mixing means combining the two signals; a ca- transmitter means initiated into operation after pacitor connected with the mixing means to have a time delay by the delay means; a first one shot 70 its charge increased when a positive pulse is not multivibrator initiated into operation by the re- neutralized by a negative pulse, said capacitor ceived pulses; rectifier means converting the out- being arranged to retain a substantial part of put of the first one shot multivibrator into a the increase in charge for a finite period after direct current enabling voltage; capacitor means the termination of the positive pulse occasioning retaining said enabling voltage for a holding in- , g the increase in charge; means directly responsive Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7 11 to each negative pulse generating a simultaneous positive pulse; and a vacuum tube amplifier hav- ing a tube with anode, cathode and grid elec- trodes, the grid bias of the vacuum tube amplifier being determined by the voltage across the ca- 5 pacitor, the grid of the vacuum tube amplifier receiving the simultaneous positive pulses, the cathode potential of the vacuum tube amplifier holding the amplifier cut off except when the simultaneous positive pulses are applied while 10 the capacitor is suitably charged, the error sig- nal being obtained from the output of the amplifier. 10. Apparatus for receiving periodic pulses and transmitting other periodic pulses in response to' 15 the received pulses so that each transmitted pulse includes in time the next succeeding received pulse and so that the transmission of pulses con- tinues through brief interruptions in the received pulses, which comprises; time delay means oper- 20 ative responsively to a received pulse; pulse trans- mitter means initiated into operation after a time delay by the delay means; pulse generator means operative to supply timing pulses at the average recurrence rate of a preceding number of re 25 ceived periodic pulses; means responsive to the timing pulses operative to initiate operation of the time delay means in the event of brief inter- ruption in the reception of the periodic pulses; means generating a first pulsed control signal re- sponsively to the trailing edges of the timing pulse; means generating a second pulsed control signal responsively to the received pulses, said second signal being of polarity opposite to that of said first signal; means mixing the first signal and the second signal to effectively neutralize the first signal when corresponding pulses of both signals occur simultaneously and to form a third signal when a pulse of the second signal occurs later than the corresponding pulse of the first signal or does not occur; means storing the third signal for a suitable interval; means applying the third signal as an error signal if and when a pulse of the second signal occurs within the interval; and circuit means operative responsively to the error signal to adjust the time delay means to maintain synchronization. 11. Apparatus for receiving periodic pulses and transmitting other periodic pulses in response to the received pulses so that each transmitted pulse -50 includes in time the next succeeding received pulse and so that the transmission of pulses con- tinues through brief interruptions in the received pulses, which comprises; time delay means oper-, ative responsively to a received pulse; pulse trans- mitter means initiated into operation after a time delay by the delay means; pulse generator means operative to supply timing pulses at the average recurrence rate of a preceding number of received periodic pulses; means responsive to the timing pulses operative to reinitiate operation of the time delay means in the event of brief in- terruption in the reception of the periodic pulses; means generating a positive pulsed control signal with leading edges coincident with the trailing edges of the timing pulses; means generating a negative pulse control signal responsively to the received pulses; mixing means combining the two control signals; a capacitor connected with the mixing means to have its charge increased when 12 means directly responsive to each negative pulse generating a simultaneous positive pulse; a vac- uum tube amplifier having a tube with anode, cathode and grid electrodes, the grid bias of the amplifier being determined by the voltage across the capacitor, the grid of the amplifier receiving the simultaneous positive pulses, the cathode potential of the amplifier holding the amplifier cut off except when the simultaneous positive pulses are applied while the capacitor is suitably charged; and circuit means responsive to the out- put of the amplifier adjusting the time delay means to maintain synchronization. 12. Apparatus for receiving periodic pulses and transmitting other periodic pulses in response to the received pulses so that each transmitted pulse includes in time the next succeeding re- ceived pulse and so that the transmission of pulses normally continues through brief interrup- tions in the received pulses, which comprises time delay means operative responsively to re- ceived pulses; pulse transmitter means initiated into operation after a time delay by the delay means; control circuit means operative to gen- erate error signals when the recurrence rate of the received pulses changes; means responsive to the error signals to adjust the time delay means to restore-synchronization; means gener- ating an enabling voltage responsively to the received signals; means rendered operative by the enabling voltage for reinitiating into operation the time delay means in the event of interrup- tions in the received pulses; means generating negative pulses coincident with the transmitted pulses; means mixing said negative pulses with the received pulses in positive polarity; and an amplifier receiving the output of said mixing means, said amplifier being responsive only when the received pulses do not occur within the in- terval occupied by the negative pulses, the output of the amplifier rendering the enabling voltage generating means inoperative. 13. A system for transmitting pulses in a se- lected time relationship to received recurrent pulses comprising, a receiver system operative to receive and amplify recurrent pulse signals, a delay pulse generator connected to the output of said receiver system operative to provide trans- mitter keying signals each bearing a selected time displacement from each received pulse signal, signal sustaining means operative to initiate op- eration of the delay pulse generator to sustain production of transmitter keying signals upon momentary interruption of received signals, and transmitter means operative to transmit an out- put pulse responsive to each transmitter keying signal. ANDREW V. HAEFF. FRANKLIN H. HARRIS. a positive pulse is not neutralized by a negative pulse, said capacitor being arranged to retain a substantial part of the increase in charge for a finite period after the termination of the posi- tive pulse occasioning the increase in charge; REFERENCES CITED The following references are of record in the file of this patent: UNITED STATES PATENTS Number Name Date 2,266,401 Reeves ------------- Dec. 16, 1941 2,272,070 Reeves -------------- Feb. 3, 1942 2,402,916 Schroeder ---------- June 25, 1946 2,402,917 Miller ------------- June 25, 1946 2,413,932 Sziklai -------------- Jan. 7,1947 2,415,359 Loughlin ------------ Feb.4,1947 2,418,127 Labin --------------- Apr. 1, 1947 2,419,548 Grieg -------------- Apr. 29, 1947 Approved For Release 2007/09/21: CIA-RDP81-0012OR000100050005-7