Nay. 5,1946. I J‘. A. RANKIN 2,410,523 PHASE-RESPONSIVE SYSTEM Filed April 21, 1945 0 FIG. bl l_.“____.____ 2b ‘32 > o 0.5.4 w INVENTOR. ' JOHN A. RANKINv I ' ‘ATTORNEYS Patented Nov. 5, 1946 UNlTED STATES‘ PATENT orrice 2,410,523 PHASE-RESPONSIVE SYSTEM John A. Rankin, Park Ridge, 111., assignor to Bel mont Radio Corporation, Chicago, 111., a corpo ration of Illinois Application April 21, 1945, Serial No. 589,471 10 Claims. (01. 250—-3.6) 1 2 This invention relates to phase-responsive sys tems and, while it is of general application, it is particularly adapted for the synchronization of scanning oscillators of television receivers from ing while its scope will be pointed out in the ap pended claims. Referring now to the drawing, Fig. l is a circuit diagram of a phase-responsive system embodying the invention as applied to the synchronization received synchronizing pulses. It has been the general practice to synchronize a scanning oscillator of a television receiver by triggering it directly with the received synchro nizing pulses after separation from the composite television signal and after separation of the line synchronizing pulses from the ?eld-synchroniz ing pulses, While ideally this arrangement is effective to initiate each scanning line and each scanning ?eld at precisely the correct point in the scanning cycles, it has been found that, in practice, it is difficult to prevent incorrect trig of a periodic wave generator from an input peri odic wave; while Figs. 2a and 2b are graphs of‘ certain operating characteristics of the system of Fig. 1 to aid in an explanation of the inven tion. Referring now to the drawing, there is repre sented a phase-responsive system embodying the invention for developing an electrical effect Vary ing with relative phase of two periodic electri cal waves, speci?cally for synchronizing a peri - odic wave generator H3 with an input periodic gering of the scanning oscillators by random wave of an integrally related frequency applied noise pulses in the received signal, particularly to input terminals l I. By the term‘ “integrally re if such pulses occur approximately at the time a lated frequency” is meant that the ratio of the synchronizing pulse is due. The result of such 20 frequency of the input wave to. that of the gen spurious triggering of the scanning oscillators is erated wave or the ratio of the frequency of the line tearing and jumping in the case of the line generated wave to that of the input wave is an scanning oscillator and, in case of the ?eld-scan integer; that is, the generated wave is a har ning oscillator, failure to interlace properly or monic or a subharmonic of the input wave while complete loss of the picture. The present inven 25 the input wave and the generated wave may be tion is directed to a phase-responsive system which, while of general application, is particularly suitable for maintaining a constant average phase relation between the received synchronizing pulses of a television signal and the scanning waves developed by the scanning oscillators of a television receiver. It is an object of the invention, therefore, to provide a new and improved phase-responsive system by means of which the average phase be tween two periodic electric waves may be main tained constant. , In accordance with the invention, a phase-re sponsive system for developing an electrical ef fect varying with the relative phase of two peri odic electrical waves comprises means for com bining the two waves with a given polarity, means of any desired wave shapes, preferably one of the waves, for example the input wave, is a rela tively broad pulse wave such as a half-sine wave, as represented adjacent the terminals ll, while the other wave developed by the generator It is a relatively narrow pulse wave, as indicated at the output connections of the generator l0 de scribed hereinafter, For example, the generator I0 may be of the conventional blocking-oscillator type comprising a vacuum tube 12 supplied with a space current from a suitable source +B through a transformer primary winding l3. The grid circuit of the tube l2 includes a transformer secondary winding Hi coupled to the winding i3 40 and a time-constant circuit including a con denser l5 effectively in parallel with a resistor It and a resistor 16a in series. The transformer for individually deriving from the waves two also includes a tertiary winding ll having its midpoint grounded and coupled to the primary bining the opposite polarity waves. The system 45 winding l3 and an output winding 9 from which also includes means for relatively time-displac may be derived the narrow-pulse wave of oppo ing at least one of the waves before combining, site polarity. means for individually rectifying the two com The system also includes means for combining waves of opposite polarity, and means for com bined waves, and an output circuit connected to the input wave at the terminals H with a wave derive the di?erence in the outputs of the two 50 derived from the generator It with the same given rectifying means. polarity, for example with a positive polarity, For a better understanding of the invention, and with the pulses thereof at least partially co together with other and further objects thereof, inciding in time. This means includes a vacuum reference is had to the following description tube repeater or ampli?er I 8 having a signal taken in connection with the accompanying draw 55 input grid to which the input signal at the ter-' 2,410,523 ' 'llfi " ‘ ‘ 4 3 'minals H is applied and an anode load resistor is and a cathode load resistor 20. This means also includes a combining or modulating tube 2| having two signal-input grid electrodes indi vidually connected to the load resistor l9 and to in a conventional manner to develop in its out put circuit a pulse voltage wave comprising a the terminal I'Ia of winding I‘! and provided be utilized in any one of a number of ways well known to the art; for example in a television receiver this pulse wave may be used to syn chronize a scanning-wave generator. This wave series of brief pulses of approximately half-sine wave shape separated by intervals determined by the time constant circuit l5, l6, 16a. This may with an anode load resistor 22. The system also includes means for individually deriving from the two waves two other Waves of opposite polarity. This means comprises the 10 comprising short duration pulses, such as the pulses b, may be derived from the output wind cathode load resistor 2i! of the tube l8 across which is developed an. input-signal pulse wave of polarity opposite to that developed across the ing 9. +3 posite or lagging sloping side of the input pulses “ The circuit constants are so proportioned that, anode load resistor l9, as indicated by the adja during normal operation, the pulses a and b at cent pulse in Fig. 1, and the other half of the 15 least partially coincide in time. As illustrated the transformer tertiary winding I‘! which supplies a pulse b falls on the leading sloping side of the generated wave of opposite polarity from the ter input pulse a._ In this ?gure the voltage 61 rep minal llb. resents the peak-recti?ed voltage developed by There is also provided a second vacuum tube the recti?er 3B and appearing across its load re combining ampli?er or modulator 23 having two sistor 32. signal-input grid electrodes one of which is con Similarly in Fig. 2b are represented the input nected to the cathode load resistor 20 to receive pulses <11 of opposite polarity as combined with the input wave of opposite polarity and the other the generated pulses in of opposite polarity. The of which is connected to the terminal lib to pulses in are delayed by the network 25 by an receive the generated wave of opposite polarity. amount such that they are still at least partially The tube 23 is provided with an anode load re coincident with the input pulses m but preferably sistor 24 while the tubes l8, 2! and 23 are sup by an amount less than the duration of one of plied with space current from a suitable source such pulses so that the pulses in fall on the op~ . . ‘The system also includes means for relatively 30 or. In this ?gure the Voltage 62 represents the time-displacing at least one of the waves before peak-recti?ed output of the recti?er 26 appearing combining and, by way of example, there is illus trated a time-delay network 25 interposed be tween the terminal Ill) and the signal grid of across its load resistor 28. The difference be tween the two recti?ed voltages e2 and er de veloped by the recti?ers 26 and 30 is derived by the combining tube 23 and effective to delay the 35 means of the control circuit 40 and the isolating resistors 3d, 35 which develop a unidirectional narrow pulse wave of opposite polarity devel bias voltage varying with the difference in the oped by the generator Hl. V _ V outputs of the two recti?ers 26 and 38 and, by way Included in the system are means for indi of the ?lter circuit 36,v apply such difference volt vidually peak-rectifying the two combined waves. This means comprising a diode recti?er 26 cou 40 age to the control electrode of the blocking oscil lator tube l2 to control the frequency thereof in pled across the load resistor 24 of the combin a well-known manner. ing tube 23 through a coupling condenser 21 and From the foregoing it will be clear that, should provided with a shunt load resistor 28. Simi the frequency of the blocking oscillator 10 tend larly, the combined wave developed across the load resistor 22 of the combining tube 2| is ap 4. to fall below that of the input synchronizing wave at the terminals H, the pulses b and b1 gen plied through a coupling condenser 3| to a diode erated thereby will tend to lag the input pulses a recti?er 30 connected with reverse polarity and and (11, respectively. This is effective to increase provided with shunt load resistor 32. the positive peak recti?ed voltage 62 and to de Connected to the two peak recti?ers described is an output circuit 40 for deriving the differ 50 crease the negative peak recti?ed voltage 24, thereby decreasing the normal negative bias on ence in the outputs of the two peak recti?ers and the grid of the tube 12 to decrease the period of comprising means responsiveto such difference the generator 10, that is to increase its frequency, for controlling the frequency of the generator until a condition of equilibrium is restored. Ob; Ill. The circuit 40 includes isolating resistors 34 viously, in case the frequency of the generator l0 and 35 connected to the load resistors 28 and tends to rise above that of the input wave at the 32, respectively, of the two recti?ers and a ?lter terminals H, the reversed process takes place. circuit 36 comprising a series resistor 31 and While theinvention has been described as ap shunt condensers 38 and 39 and is connected to plied to a frequency divider, that is an arrange the junction between time-constant resistors l6 and Ilia in the grid circuit of the blocking-oscil 60 ment for generating a pulse wave which is a sub harmonic of the input wave, it will be apparent lator generator E0. that it is equally applicable to a system having The operation of the phase-responsive system any other integral frequency relation between the of the invention may be best understood by ref erence to Figs.w2a and 2b, which illustrate the . input wave and that developed by the generator invention as applied to the synchronization of 65 In. It ‘is only necessary that the pulses a and b, and a1 and b1 coincide in time, which necessarily the generator [0 at the fourth subharmonic of follows from the integral frequency relationship. the input wave, that is, with the system oper In the case of frequency multiplication, a plu ating as a frequency divider. In Fig. 2a the pulses rality of pulses b and b1 will fall between each a represent the input wave of positive polarity developed across the load resistor l9 and applied 70 adjacent pair of pulses a and ‘a1, respectively, while in the case in which the frequency of the to an input grid of the combining tube 2!. The input wave is the same as that generated by the pulses 17 represent the pulses derived from the blocking oscillator 10, one of the pulses b or In blocking oscillator 10 supplied from the terminal will fall on each of thevpulses a or an, respec Ha, to the other signal input grid of the com tively. In the case of frequency multiplication bining tube 2|. The blocking oscillator operates 75 acids-2s kg or- frequency division the average voltaigesbuilt up on condensers 2T and‘S'li'by the peak recti?ers , 26. and 301, respectively, :act. as biases on therecti ?ers andv prevent their‘ response to. eithertheaine put wave or the generated-wave alone and limit their response to the combined input. and gener— ated Wave. It. will further be apparent that: any of the four waves utilizedto develop the control 6 coinciding; in time, means for individually deriv-v ingfromsaidjwaves two waves of opposite polar ity, means} for‘ combining; said opposite-polarity waves, means for relatively time-displacing. at least one of said waves before combining‘ byan amount such that the pulses thereof‘ are still at least partially coincident with’ those of the wave with which it is combined, meansv for indi voltage may be advanced or'retardecl with respect viduallyi rectifying said two combined waves, and to the others to.v produce. the desired ultimate rela 10 an output’ circuitconnected to derive the di?er tive time displacement anduthat either the-input ence in the outputs of said rectifying means. waves or-the generated waves‘ of opposite polari '3. A’ phase-responsive. system for developing ties may both be shifted with respect ,tothe other an electrical e?‘ect varying with the; relative in orderto provide a differentaverage phase re-, . phase of two periodic electrical pulse waves ‘of " lation between the input Waves andthe. generated integrally related frequencies, one wave consist ing of relatively broad pulses and; the other of An important advantage of the phase-respon relatively narrow pulses, comprising, means for sive system described resides in the, fact that, it combining the two waves with a given polarity waves. , I ~ -_ is, substantially completely unresponsive toes-puri and with the pulses thereof at least partially ous noise pulses which may be present in the 20 coinciding inv time, means for individually deriv pulse Wave a appearing at the input circuit 1 I. ing from said waves two waves of opposite polar This characteristic can be seen by reference to ity, means for combining said opposite-polarity Figs. 2a and 2b in which there are represented waves, means for relatively time-displacing said noise pulses n and- m appearing on the pulse narrow-pulse waves of opposite polarities. before waves- a and d1 of opposite polarity and, impressed 25 combining by an amount less than the duration upon the peaked recti?ers 25. and 3%], respectively. of one of said- broad pulses, means for individue Due to the fact that these two noise pulses n ally rectifying said two combined waves, and an and. m are of the same phase and of opposite output circuit connected to derive the difference polarity, their effects on the recti?eeloutputs of in the outputs of said rectifying means. therecti?ers 2B and 30v are equal and opposite 30 4. A phase-responsive system for developing so that. no net noise component is impressedv upon an» electrical effect varying with’ the relative the control circuit at. rlFhis is true for all. con: ‘ phase of two; periodicv electrical. pulse waves : of dition's, except in the case of av noise pulse which, integrally related frequencies comprising, means coincides in time with a portion of one of the de— for combining the two waves with» a given polar rived pulses b or bi. By making the pulsesb as. , ity and with the pulses thereof at least partially narrow as possible, the chance of a. noisepulse coinciding in time, means for individually derive n coinciding With a pulse b is minimized. How; ing from said waves two-waves of opposite polar- ' ever, even in‘this case the only e?ect of the noise ity, means for combining said opposite-polarity pulses is that due to their average energy content, waves, means for relatively time-displacing at which ordinarily is inappreciable. Thus, it is seen 4:0 least one of said waves before combining, means that in the arrangement described the blocking oscillator I0 is not excited directly by the input synchronizing pulses at the terminals H and thus for individually peak rectifying said two com bined waves, and an output circuit connected to derive the difference in the outputs of said is completely shielded from any random or spuri rectifying means. ous noise pulses appearing at the input termi 45 5. A phase-responsive system for» synchroniz nals. The only effect of such spurious pulses on ing a periodic-wave generator with an input the operation of the system is that due to their periodic wave of an integrally related frequency average energy content which, as explained above, comprising, means for combining the input wave is inappreciable. with a wave derived from the generator with a While there has been described what is at pres ent considered to be the preferred embodiment 50 given polarity, means for individually deriving from said waves two waves of opposite polarity, of the invention, it will be apparent to those means for combining said opposite-polarity skilled in the art that various changes and mod waves, means for relatively time-displacing at i?cations may be made therein without depart least one of said waves before combining, means ing from the spirit or scope of the invention. What is claimed as new is: 1. A phase-responsive system for developing an electrical e?ect varying with the relative ' phase of two periodic electrical waves compris ing, means for combining the two waves with for individually rectifying said two combined waves, and means responsive to the difference in the outputs of said rectifying means for con trolling the frequency of said generator. 6. A phase-responsive system for synchronizing a periodic-wave generator with an input periodic a given polarity, means for individually deriving 60 wave of an integrally related frequency com from said waves two waves of opposite polarity, prising, means for combining the input wave with means for combining said opposite-polarity a wave derived from the generator with a given waves, means for relatively time-displacing at polarity, means for individually deriving from least one of said waves before combining, means 65 said waves two waves of opposite polarity, means for individually rectifying said two combined for combining said opposite-polarity ‘waves, waves, and an output circuit connected to derive means for relativelytime-displacing at least one the difference in the outputs of said rectifying of said waves before combining, means for indi~ means. vidually rectifying said two combined waves, and ' 2. A phase-responsive system for developing a circuit for developing a unidirectional bias an electrical effect varying with the relative voltage-varying with the dilference in the out phase of two periodic electrical pulse waves of puts of said rectifying means for application to integrally related frequencies comprising, means said generator to control the frequency thereof. for combining the two waves with a given polar ,7. A phase-responsive system for synchronizing v ity and with the pulses thereof at least partially 75 a periodic-wave generator with an input periodic 2,410,523 8 wave' of’ an". integrally related frequency com prising, means for combiningthe input wave with for producing a scanning wave and means for deriving a synchronization wave for controlling a wavederived from the‘generator with’a given polarity, means for individually deriving from said scanning generator; a phase-‘responsive sys tem for synchronizing said generator with said said waves two waves of opposite polarity, means synchronization wave comprising, means for com-v for vidually rectifying said two combined waves, and means responsive to the difference in the outputs bining said‘ synchronization wave with said scanning wave, means for individually deriving from said waves two waves of opposite polarity, means for combining said opposite-polarity waves, means for relatively time-displacing at least one of said waves before combining, means of said'rectifying means for controlling the fre quency of said generator, whereby the synchroni zation of said generator is substantially un waves, and means responsive to the difference in the outputs of said rectifying means for controll combining said opposite-polarity waves, means for relatively time-displacing one of said generated waves before combining with the input wave of corresponding polarity, means for indi for individually rectifying said two combined affected by spurious noise pulses superimposed on 15 ing the frequency of said generator. said input wave. 8. A phase-responsive system for synchronizing a periodic-wave generator generating a relatively narrow pulse wave with an input periodic wave comprising relatively broad pulses‘ and of an integrally related frequency comprising, means for combining the input wave with a wave derived from the generator with a given polarity, means ’ 10. In a television system including a generator for producing a scanning pulse wave and means for deriving an input synchronization pulse wave for controlling said generator; 2. phase-responsive system for synchronizing said generated pulse wave with said synchronization pulse wave com prising, means for combining the two waves with, a given polarity and with the pulses thereof at least partially coinciding in time, means for indi for individuallyv deriving from said waves two waves ‘of opposite polarity, means for combining 25 vidually deriving from said waves two waves of opposite polarity, means for combining said op said opposite-polarity waves, means for relatively posite-polarity waves, means for relatively time time-displacing one of said generated waves be displacing at least one of said waves before com fore combining with the input wave of corre sponding polarity, means for individually rectify bining, means for individually peak rectifying ing said two combined waves, and means re 30 said two combined waves, and means responsive sponsive to the di?erence in the outputs of said rectifying means for controlling the frequency of said generator, whereby the synchronization of said generator is substantially unaffected by spurious noise pulses superimposed on said input wave. ‘ ' 9. In a television system including a generator to the difference in the outputs of said rectifying means for controlling the frequency of said gen erator, whereby the synchronization of said gen erator is substantially unaffected by spurious noise pulses superimposed on said input synchronization wave. JOHN A. RANKIN.