US2265979A - Television synchronization - Google Patents

Television synchronization Download PDF

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Publication number
US2265979A
US2265979A US224095A US22409538A US2265979A US 2265979 A US2265979 A US 2265979A US 224095 A US224095 A US 224095A US 22409538 A US22409538 A US 22409538A US 2265979 A US2265979 A US 2265979A
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Prior art keywords
impulses
scanning
network
duration
polarity
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Expired - Lifetime
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US224095A
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English (en)
Inventor
Below Fritz
Gunther Johannes
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FIRM OF FERNSEH AG
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FIRM OF FERNSEH AG
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Publication date
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Publication of US2265979A publication Critical patent/US2265979A/en
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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
    • H04N5/10—Separation of line synchronising signal from frame synchronising signal or vice versa

Definitions

  • invention relates toa method of synchronizing transmitters and receivers for television.
  • Figure 1 shows the output of the network shown in Figure 2;
  • Figure 4 shows ing impulses for synchronization of scanning wave generators in receivers with those at a transmitter, and to transmit such synchronizing impulses during periods in which nopicture signals are transmitted. It is common practice to use the so-called retrace periodfor this purpose. It is also known to transmit two types of im pulses for synchronization of the-vertical and horizontal scanning generators, respectively.
  • the duration of the synchronizing impulse for the vertical scanning usually exceeds the duration of a scanning line by several times.
  • the horizontal or line scanning generator is preferably synchronized at the end of each line, also during the occurrence of the framing impulse, in order to avoid drifting of the horizontal scanning wave generator, special measures are .necessary to secure line synchronization during this time. Ithas been proposed, for instance, to serrate a framing impulse at periodic intervals, and to insert line synchronizing impulses in the serrations, or to serrate the synchronizing impulses at periodic intervals and to synchronize the line scanning generatorsat one edge of the serrations.
  • Figure 1 shows a series of synchronizing impulses, the short impulses being for line synchronization, the'impulse of longer duration a framing impulse.
  • the line synchronizing impulses may have a duration of 10% of a line period
  • This signal is fed through a network as showri in Figure 2, comprising a capacitance'land a resistor 2.
  • the value of the capacitance I maybe made approximately 1,000 micromicrofarads, and that of resistance 2 approximately 50,000 ohms, These values render a time constant at which the line synchronizing impulses will remain substantially undistorted when passing through the network.
  • the framing impulsesof longer duration will become considerably distorted, as Figure 3 illustrates, which represents the output of the network according to Figure 2 taken across resistance 2.
  • Figure 1 shows a synchronizing impul es intersp rsed a r-raining impulse
  • Figure 2 shows the net-* following line synchronizing impulse also proure 3, which can be used-for synchronization of the vertical scanning generator.
  • This peak impulse is of opposite polarity to the line synchronizing impulses so that discrimination between framing andline synchronizing impulses can be polarity.
  • the coupling condenser land grid leak resistor 2 constitute the network shown in Figure 2.
  • the output of the network is directly applied to the control grid or screen grid of an amplifier tube 4.
  • the bias of tube 4 is so chosen that the tube does not draw current on the peak impulses caused by line synchronizing impulses.
  • the plate circuit of tube 4 is capacitatively coupled to the vertical scanning generator 6 at the terminal 5.
  • any network 20 5 A television scanning system comprising a network including impedance elements and .being which substantially suppresses all frequencies below a frequency greater than the vertical scanning frequency, and lower than the horizontal scanning frequency, will produce the required resuits.
  • the method of synchronizing a scanning operation comprising the steps of transmitting a series of impulses of equal amplitude andpolarity, certain impulses possessing a longer duration than others, applying said series of impulses to a network allowing the impulses of short duration to pass through saidnetwork substantially undistorted, and causing said impulses aof'longer' duration to produce impulses having ⁇ a' polarity opposite to said first named polarity upon passing through said network, applying the resultant series of impulses to a first scanning'wave-generator sensitive to impulses of one polarity onlyvand applying the same result ant series lof-impulses'to a second scanning wave generator sensitive to impulses of the opposite polarity only.
  • the method of synchronizing a scanning operation comprising the" steps of transmitting a series of impulses of equal amplitudeand polarity, certain impulses possessing a longer duration than others, applying said series of impulses to a network allowing the impulses of short duration to pass through said network substantially'undistorted, and causing said impulses at longer duration to produce impulseshaving apolarity opposite to said first named polarity ,upon passingthrough said network, applying the resultant series of impulses-to a ,vertical 'sca'nning wave generator in such polarity thatit responds to saidimpulses of opposite pol- 10 ing longer durations than others, said impedance elements being so proportioned as to permit passage through said network of the impulsw of shorter duration substantially without distortion thereof and to render said network so responsive to said impulses of longer duration as to derive therefrom impulses having a polarity opposite to that of the applied impulses, and means for utilizing only said impulses of opposite polarity to synchronize scanning operations in said
  • said impedance elements being so proportioned as-to provide a time constant of the order of the durationof said impulses having longer durations, thereby to derive from said impulses of longer duration im- 80 pulses having a polarity oppositetothat' of the applied impulses, and means for :utilizing only said impulses of opposite polarity. to synchronize scanning operations in said system.
  • a television scanning system jcornprising a 85 network includirifcapacitantbe and resistance elements connectedin series relation and being adapted to have applied thereto a series of impulses of substantially equal amplitudes andvof the same polarities,- certain of; said impulses havi40 ing longer durations than others saideimpedance elements being so proportioned as ta permit passage through said network of the impulses of shorter duration substantially without distortion thereof and to cause said impulses of longer duration .to develop across said resistance element impulses having a polarity opposite tpfthat of the applied impulses, .and means for" utilizing only said impulses of opposite polarity to' synchronize scanning operations in said-:sys'tem.
  • a television scanning system comprising a network including impedance elements and being adapted to have applied thereto aseries of impulses, of substantially equal amplitudes and of the'same polarities, certain of said impulses hav-- ing'longer durations than others, said p dance (50 ration to develop across one of: said impedance elements impulses having a pglarityopposite to that of the ,appliedimpulses and-initiated by the trailing edges of ;said applied impulses aof longer duration, and means for utilizinggoply said im- 65 pulses of opposite polarity tofsynchronize scanning operations in said system.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
US224095A 1937-08-17 1938-08-10 Television synchronization Expired - Lifetime US2265979A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2265979X 1937-08-17

Publications (1)

Publication Number Publication Date
US2265979A true US2265979A (en) 1941-12-16

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
US224095A Expired - Lifetime US2265979A (en) 1937-08-17 1938-08-10 Television synchronization

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US (1) US2265979A (de)
BE (1) BE429694A (de)
FR (1) FR842232A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2616976A (en) * 1947-03-05 1952-11-04 Hartford Nat Bank & Trust Co Multiplex radio receiver
US2733293A (en) * 1956-01-31 Neumann

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE952273C (de) * 1952-03-26 1956-11-15 Siemens Ag Anordnung zur Umwandlung von Impulsen, vorzugsweise zur Synchronisierung der Ablenkorgane eines Fernsehgeraetes

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2733293A (en) * 1956-01-31 Neumann
US2616976A (en) * 1947-03-05 1952-11-04 Hartford Nat Bank & Trust Co Multiplex radio receiver

Also Published As

Publication number Publication date
FR842232A (fr) 1939-06-08
BE429694A (de)

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