US1940161A - Synchronizing system - Google Patents

Synchronizing system Download PDF

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Publication number
US1940161A
US1940161A US531794A US53179431A US1940161A US 1940161 A US1940161 A US 1940161A US 531794 A US531794 A US 531794A US 53179431 A US53179431 A US 53179431A US 1940161 A US1940161 A US 1940161A
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United States
Prior art keywords
signals
synchronizing
current
television
circuit
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Expired - Lifetime
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US531794A
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English (en)
Inventor
Barthelemy Rene
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Compteurs Schlumberger SA
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Compteurs Schlumberger SA
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/04—Synchronising
    • H04N5/08—Separation of synchronising signals from picture signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/16—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/16—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level
    • H04N5/165—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level to maintain the black level constant

Definitions

  • the present invention has reference to a method and means enabling the local oscillation to be started solely through the agency of the synchronizing top, to the exclusion of the other signals emitted by the sending apparatus and which are generally transmitted on the same carrier wave as the synchronizing signal.
  • the principle oi the invention consists in produclng by means of the synchronizing top a modulation of the carrier wave which corresponds to a variation 01! the virtual value of said wave of opposite sign to that which would be produced by the television signals.
  • To these two modulations correspond two variations of opposite sign of the mean current detected in the receiver and with this difference of signs it is easy to eliminate the effects of the television signals on the synchronizing system.
  • a simple means for enabling the two sorts of signals to be diiierentiated at the sending end consists in causing the top to modulate by momentarily raising the plate voltage of the oscillating valve, whereas the modulated television signals are applied to the grid circuit of said lamp through the medium of a suitable impedance between the time intervals which separate two successive tops; this kind of modulation generally lowers the virtual current in the aerial.
  • a further object of the invention is to increase the security of selection by mounting in the deteeter circuit a stopper" circuit tuned to the frequency of the synchronizing top and from the ends of said circuit is tapped the synchronizing voltage of suitable frequency, phase and am.- plitude, which may then be applied, amplified or not, to the motor to be synchronized or any other equivalent system.
  • Fig. 1 illustrates a transmitting device modulated according to the invention.
  • Fig. 2 illustrates a suitable receiver for use with the transmitting device of Fig. 1.
  • Fig. 3 illustrates a modified circuit arrangement for the receiving device of Fig. 3.
  • Fig. 4 illustrates a further modification of the receiving device of Fig. 3.
  • Fig. 5 is a graph of the oscillations received by the device of Fig. 4.
  • Fig. 6 is a graph of the oscillations after selection effected by the device of Fig. 4.
  • Fig. 7 is a circuit arrangement of an automatic device for regulating the grid bias of the receiver of Fig. 4, and
  • Fig. 8 illustrates a modification of the device of Fig. 7, and Fig. 9 a modification of the device of Fig. 8.
  • an oscillating valve 0 (which may be replaced by a bank of valves and may be followed by a high frequency amplifier if high powers are to be obtained) produces the continuous wave of suitable frequency by means of conventional reaction couplings, for example the electromagnet coupling of an oscillating cir cult constituted by the coil B and the condenser K with an inductance Ci mounted in the grid circuit.
  • Another suitable inductance A coupled to the coil B transmits the energy to the aerial, an earth having been featured at T.
  • the modu-- lation of the apparatus by the television oscillations is accomplished by applying the modulating voltage coming in at M and N to the resistance R which may also be an inductance.
  • a very small capacity C lets through the high frequency carrier current. Modulation is thus effected by variation of the grid potential and it is observed that the virtual current in the aerial decreases when the strength of said. modulation is increased.
  • Said modulation is discontinued at each complete scanning of the image. for a very short interval of time, during which time interval the synchronizing top" is transmitted.
  • a switch Z rotating synchronously with the spindle of the scanning disc, breaks the current fed by a direct current source E to the primary P of a transformer, at the exact moment when the television modulation is interrupted.
  • the connec tions being suitably established, an additional voltage, lasting a very short length of time, for example 1/10,000th of a second, is introduced by the secondary S into the plate circuit of the oscillating valve and is added to the normal direct voltage.
  • the virtual current in the aerial is suddenly increased and such excess current easily attains a value equal to the ordinary current.
  • the current resumes its normal value when the energy stored up in the transformer is practically dissipated by the valve. Then the grid modulation starts again arid the direct current source E again feeds the primary P, the time for establishing the Bill necessary current being calculated so as to be of the order of of a second.
  • the excess voltage may be introduced into the plate circuit in any other manner without departing from the present invention.
  • the drawbacks attendant on a switch breaking a certain current may be avoided by substituting therefor the filament-plate circuit of a three electrode valve and by using the synchronous commutator to vary considerably the grid bias without breaking the current.
  • the signals will be selected by using the detected current, or a current proportional thereto, after amplification.
  • Said current 2' generally flows through the plate of a valve and an anode resistance or impedance p (Fig. 2).
  • a fraction r of said resistance will be used to start the local oscillation derived from the neon tube L, the condenser Y, the resistance D and the source P, which device was disclosed in applicants U. S. application Serial No. 415,537 filed December 20th, 1929.
  • Another object of the invention is to enable the two types of signals to be selected with complete security. Its principle is based on the combination of an impedance (in general a resistance) through which fiows the said plate current, with an auxiliary electromotive force and a system having a more or less perfectly unilateral conductability similar to a detector. It will be understood a priori that with the connections suitably established and for a suitable value of the auxiliary electromotive force, the detector can choke all the television oscillations and only let through the synchronizing signal.
  • the detector system is constituted by the filamentgrid space of a triode S.
  • the plate current i of the detector valve D flows through the resistance R and produces a difference of potential Ri which decreases by at least one quarter of its valve upon receptionof a synchronizing top.
  • the grid of the valve S is subjected to said potential difference Ri through the medium of a grid biassing battery E.
  • the voltage of said battery is such that a negative potential is-impressed on the grid of the valve S (for the mean value of R2 corresponding to the modulating television signals) which annuls the plate current of said valve S.
  • said signals have no effect on the transformer T.
  • the incoming synchronizing signal causes R2 to fall appreciably in value during the duration of said synchronizing signal, which moreover is very short, and the grid potential of the valve S rises during this time to a higher value thereby giving rise to an anode current which flows through the primary of the transformer T.
  • the making or breaking of this current generates an electromotive force in the secondary which is utilized to light up the pilot lamp disclosed in certain of my co-pending applications, and in particular in the aforementioned application Serial No. 415,537 filed December
  • the condenser K shunted across the ends of the primary of the transformer T constitutes with the self-inductance of said primary the stopper circuit referred to above and still further promotes selection of the signals.
  • the television signals are transmitted to the succeeding amplifying valves such as BF by means of any suitable coupling, as for example a condenser C.
  • the invention is likewise concerned with a modified circuit arrangement of the detector-selector at the receiving end.
  • the current variations detected by television are transmitted and amplified by an amplifier which must be designed to faithfully reproduce a large range of frequencies; in Fig. 4 the current oscillations detected-are applied through the medium of a condenser C and a resistance R on the controlling grid g of an amplifying valve.
  • Fig. 5 have been illustrated the voltage oscillations which take place in the resistance R.
  • the grid voltage drops by an amount of mean value a.
  • the oscillations of maximum amplitude are for example (ua+u:), then upon passage of the synchronizing signal, the grid voltage increases by us which is substantially higher than the value m.
  • the valve is used as a detector, the television signals will be eliminated and, the grid being suitably biassed, only the oscillations of the anode current i in the transformer T due to the synchronizing signals will be observed (Fig. 6). With sufilcient negative grid bias, the plate current will be annulled even in the case of the strong- Obviously the valve might include other electrodes and the grid be charged through the medium of another coupling without departing from the spirit of the invention.
  • the current pulsations obtained may then be readily used for synchronizing with extreme accuracy the rotation of the television scanning disc, by using the devices disclosed in others of my patents.
  • the above described method of separating synchronizing from television signals by using the bend of the characteristic curve of a receiving valve and negatively biassing its grid requires that the bias shall be sufficient to prevent television signals from producing oscillations in the plate circuit of the valve, but it must not be so great that the synchronizing signal is also choked.
  • the mean value of the biassing voltage must therefore be determined as a function of the current at the receiving end. Such adjustment is readily accomplished but if the current at the receiving end is variable, as is frequently the case, in wireless transmission, this operation becomes diflicult.
  • the invention is likewise concerned with an automatic adjustment for the biassing voltage obtained by producing said voltage by the received current itself, of course after suitable transformation.
  • a television receiver having for example 3 stages of amplification includes a detector valve 1 and two amplifying valves 2 and 3, the latter acting on the luminescent tube N.
  • Another valve 4 having suitable grid bias is provided for selecting the synchronizing signal, the amplitude of which is considerably greater than that of the television signals, and the brief pulsations of the synchronizing "top are converted in the anode circuit of said valve into oscillations of longer duration, by means of the condenser K and the transformer T in the manner indicated above; these long oscillations can then be utilized in the synchronizing device.
  • the bias u is therefore proportional to the mean current received taken over a very long time interval.
  • Another arrangement based on the same principle consists in using the rectifying properties of the triode 4 itself to obtain a valve effect and in using the voltage taken from the filament plate circuit in a suitable filter, the whole or part of the purified voltage derived therefrom being used to bias the grid in the manner desired.
  • Fig. 8 shows the detail of this device, which in addition to the advantage of simplicity only uses the energy proportional to the synchronizing signal, to the exclusion of the television signals, and feeds to the synchronizing circuit power which within wide limits is independent of the power received. This quality is of great value for the stability of the images in television.
  • the television amplifier receiver supplies at S a composite voltage one component of which is the television and synchronizing signals alternately, the amplitude of the latter being considerably greater than that of the television signals.
  • This voltage is applied to the resistance 9 connecting the grid to the usual common point.
  • An auxiliary biassing battery P which is not involtage R2, decreases.
  • the dispensable is so designed that in the absence of the signals, the anode current i supplied by the source U is practically nil. Under the effect of the incoming signals, the current 1 assumes a mean value which is not nil and the flow of said current in the resistance R produces a voltage drop which biases the grid negatively with respect to the cathode.
  • R is so chosen moreover that the bias obtained shall be sufficient so that television signals proper shall take no part in producing the anode current and that only' the synchronizing signals of suificient amplitude shall produce the anode current and, consequently, automatically maintain the biassing voltage. Under these conditions, only the pulsations due to synchronization are transmitted to the motor M or to an additional amplifier through the medium of the transformer T combined with the condenser C. It is thus seen that the influence of the television modulation is completely eliminated.
  • the intensity of the synchronizing oscillations transmitted to the motor M is substantially constant, which is explained by the fact that if the incoming signals increase in strength, for example, the biassing voltage increases and, simultaneously, the real anode voltage, which is equal to the voltage U minus the These two efiects are cumulative, if the valve characteristics be considered, and limit the increase of power in the anode circuit which would be introduced by the increase in the strength of the signals and which would exist were the plate and grid potentials constant.
  • the circuit may be modified in several ways without departing from the scope of the invention.
  • a filter having several cells with a large time constant (not shown) may be usei in Fig. 8 has been disclosed an independent filament heating battery A but instead of said independent heating source the device of Fig. 9 may be used in which the cathode C of the valve 4 is indirectly heated by a filament F connected to the supply mains G.
  • the advantage of this modification is that the potential of the cathode C can be adjusted at will.
  • a device for transmitting synchronizing signals using a carrier wave which is likewise modulated by a difierent type of signals such as television signals the combination of an oscilla ticn generating triode having an input and an output circuit, means for impressing the carrier wave frequency on the input circuit of said valve, means for impressing television signals on the input circuit of said valve to modulate said carrier wave, and periodically operative means for impressing the synchronizing signals on the output circuit of said valve, the transmission of the television signals being discontinued during the transmission of the synchronizing signals.
  • a device for transmitting and receiving synchronizing signals using a carrier wave which is likewise modulated by a different type of signals, such as television signals the combination of an oscillation generating valve, means for impressing the carrier wave frequency on the grid circuit of said valve, means for impressing said television signals on the grid circuit of said valve, periodically operative means for impressing the synchronizing signals on the plate circuit of said valve, the transmission of the television signals being discontinued during the transmission of the synchronizing signals, receiving apparatus including a triode and means for impressing said modulated signals on the input side thereof, and means associated with said triode for deriving from the output side thereof diiferent potentials corresponding to the television signal and synchronizing signal modulations respectively.
  • a device for transmitting and receiving synchronizing signals using a carrier wave which is likewise modulated by a different type of signals such as television signals the combination of an oscillation generating triode, means for impressing the carrier wave frequency and modulating television signals on the input circuit of said triode, periodically operative means for impressing the modulating synchronizing signals on the output side of said triode, the transmission of said television signals being discontinued during the transmission of said synchronizing signals, a receiving triode on the input side, of which said modulated carrier wave is impressed, and an impedance mounted in the plate circuit of said receiving triode and across which a potential may be derived which is greater in the case of television signal modulations than in the case of synchronizing signal modulations.
  • a device for transmitting and receiving synchronizing signals using a carrier wave which is likewise modulated by a different type of signals such as television signals the combination of means for transmitting a carrier wave, means, alternating in operation, for producing modulations of said carrier wave by television signals and synchronizing signals respectively, said two kinds of modulations being of opposite signs with respect to the virtual value of said carrier wave, a receiving rectifying triode on the input side of which said modulated carrier waves are impressed, an impedance mounted in the plate circuit of said rectifying triode, and across which a higher potential is created on reception of said television signal modulations than on reception of said synchronizing signal modulations, an additional triode, a biassing battery mounted in the grid circuit of said additional triode and adapted in conjunction with said impedance to bias said grid negatively, said biassing battery being adapted when assisted by the potential across said impedance due to reception of said television modulations to bias the grid of said rectiher so strongly that substantially no current flows in the plate circuit of said rectifier whereas current flows therethrough
  • a device in combination with a stopper circuit mounted in the plate circuit of said rectifier and tuned to the synchronizing signal frequency.
  • a device for transmitting and receiving synchronizing signals using a carrier wave which is likewise modulated by a different type of signals such as television signals the combination of means for transmitting a carrier wave, means, alternating in operation, for producing modulations of said carrier wave by television signals and synchronizing signals respectively, said two kinds of modulations being of opposite signs with respect to the virtual value of said carrier wave, a receiving triode including a grid circuit on which said modulated carrier waves are impressed, an impedance, and a biasing battery mounted in series with said impedance in said grid circuit, said battery being adapted to bias said grid negatively to such an extent that only the synchronizing signal modulations, but not the television signal modulations, are of sufficient amplitude to permit a plate current to flow.
  • a device for transmitting and receiving synchronizing signals using a carrier wave which is likewise modulated by a different type of signals such as television signals the combination of means for transmitting a carrier wave, means, alternating in operation, for producing modulations of said carrier wave by television signals and synchronizing signals respectively, said two kinds of modulations being of opposite signs with respect to the virtual value of said carrier wave, receiving apparatus including a triode, an impedance mounted in thegrid circuit of said triode, means for impressing the television and synchronizing modulations on the grid circuit of said triode, means for converting incoming television and synchronizing modulations into direct voltage, and means for applying said direct voltage across said impedance to bias said grid whereby only the synchronizing signal modulations are of suflicient amplitude to produce a current on the plate circuit of said triode.
  • a device for transmitting and receiving synchronizing signals using a carrier wave which is likewise modulated by a different type of signals such as television signals the combination of means for transmitting a carrier Wave, means alternating in operation, for producing modulations of said carrier wave by television signals and synchronizing signals respectively, said two kinds of modulations being of opposite signs with respect to the virtual value of said carrier wave, receiving apparatus including a rectifying triode, a plurality of amplifying triodes and a synchronizing signal selecting triode on the grid circuit of which the television and synchronizing signal modulations are impressed after rectification and amplification, an impedance mounted in the grid circuit of said synchronizing signal selecting triode, means for converting the rectified and amplified signal modulations into direct voltage, and means for applying said direct voltage across said impedance to bias the associated grid whereby only the synchronizing signal modulations are of sufficient amplitude to produce a current in the pate circuit of said synchronizing signal selecting triode.
  • a device in which said means for converting the rectified and amplified modulations into a direct voltage comprise a rectifying tube and a filter circuit in circuit therewith.
  • a filter circuit mounted in the plate cir cuit of said additional triode and adapted to choke any television modulations that may get through to the plate circuit of said additional triode.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Television Receiver Circuits (AREA)
  • Luminescent Compositions (AREA)
  • Secondary Cells (AREA)
  • Hybrid Cells (AREA)
US531794A 1930-05-21 1931-04-21 Synchronizing system Expired - Lifetime US1940161A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR579664X 1930-05-21

Publications (1)

Publication Number Publication Date
US1940161A true US1940161A (en) 1933-12-19

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Application Number Title Priority Date Filing Date
US531794A Expired - Lifetime US1940161A (en) 1930-05-21 1931-04-21 Synchronizing system

Country Status (5)

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US (1) US1940161A (fr)
DE (1) DE579664C (fr)
FR (5) FR711446A (fr)
GB (1) GB363605A (fr)
NL (1) NL48119C (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2577355A (en) * 1944-12-09 1951-12-04 Bell Telephone Labor Inc Pulse forming and shaping circuits

Families Citing this family (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE967256C (de) * 1933-02-10 1957-10-31 Emi Ltd Schaltungsanordnung zur Gewinnung der einen bestimmten Mindestwert ueberschreitenden Amplituden eines Synchronimpulses
BE401738A (fr) * 1933-03-01
BE402568A (fr) * 1933-04-13
DE756008C (de) * 1933-05-20 1954-11-22 Opta Radio A G Anordnung zur Aussiebung der Synchronisierimpulse und zur Regelung des Verstaerkungsgrades
US2178234A (en) * 1934-02-28 1939-10-31 Rca Corp Television system
DE748742C (de) * 1934-07-31 1944-11-09 Fernsehsendeverfahren, bei dem die Bildmodulation von der einen Seite und die Bildwechsel-Synchronisierimpulse von der anderen Seite eines festgelegten Wertes (Schwarzwert bzw. Wert groesster Helligkeit) aus gegeben Werden
NL46321C (fr) * 1934-09-18
GB450675A (en) * 1934-11-19 1936-07-20 Cecil Oswald Browne Improvements in or relating to television and the like transmitting systems
DE972011C (de) * 1935-06-12 1959-05-06 Fernseh Gmbh Doppelseitiges Amplitudensieb
BE422316A (fr) * 1936-07-05
DE766547C (de) * 1936-11-12 1954-08-09 Fernseh Gmbh Schaltung mit veraenderlichem Verstaerkungsgrad zur Verstaerkung von Bildzeichen
DE959375C (de) * 1937-07-22 1957-03-07 Telefunken Gmbh Schaltungsanordnung zur Synchronisierung eines Vorganges mittels Impulsen, insbesondere fuer Fernsehzwecke
US2240507A (en) * 1938-10-05 1941-05-06 Hazeltine Corp Television synchronizing and control system
DE751692C (de) * 1941-02-27 1953-12-21 Lorenz C Ag Messverfahren, insbesondere fuer Breitbandkabel
DE975765C (de) * 1941-12-13 1962-08-23 Philips Nv Vorrichtung zum Empfang von mit Hilfe von Impulsen konstanter Amplitude uebertragenen Signalen
BE490426A (fr) * 1944-07-13
DE977647C (de) * 1950-07-21 1967-11-30 Aga Ab Vorrichtung zur Abtrennung der Synchronimpulse bei einem Fernsehempfangsgeraet
US2698358A (en) * 1950-11-30 1954-12-28 Rca Corp Video amplifier control by combined a. g. c. and d. c. voltages
DE959113C (de) * 1951-06-16 1957-02-28 Interessengemeinschaft Fuer Ru Schaltung zur Abtrennung von Synchronisierimpulsen aus einem Signalgemisch mit Hilfe einer vorgespannten Diode
DE1168950B (de) * 1956-04-13 1964-04-30 Loewe Opta Ag Schaltungsanordnung zur Stoerunterdrueckung bei der Abtrennung der Synchronisierimpulse in der als Mehrgitterroehre ausgebildeten Amplituden-siebroehre eines Fernsehempfangers
GB933262A (en) * 1959-03-26 1963-08-08 Int Computers & Tabulators Ltd Improvements in or relating to amplitude selection circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2577355A (en) * 1944-12-09 1951-12-04 Bell Telephone Labor Inc Pulse forming and shaping circuits

Also Published As

Publication number Publication date
FR711446A (fr) 1931-09-09
FR39944E (fr) 1932-03-19
GB363605A (en) 1931-12-24
NL48119C (fr)
FR40289E (fr) 1932-06-08
DE579664C (de) 1933-07-01
FR49468E (fr) 1939-05-01
FR40750E (fr) 1932-08-22

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