US2384931A - Synchronizing generator - Google Patents

Synchronizing generator Download PDF

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Publication number
US2384931A
US2384931A US426695A US42669542A US2384931A US 2384931 A US2384931 A US 2384931A US 426695 A US426695 A US 426695A US 42669542 A US42669542 A US 42669542A US 2384931 A US2384931 A US 2384931A
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US
United States
Prior art keywords
frequency
oscillator
linearity
pulse
master
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US426695A
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English (en)
Inventor
Robert E Kessler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Allen B du Mont Laboratories Inc
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Allen B du Mont Laboratories Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE463823D priority Critical patent/BE463823A/xx
Application filed by Allen B du Mont Laboratories Inc filed Critical Allen B du Mont Laboratories Inc
Priority to US426695A priority patent/US2384931A/en
Priority to GB379/43A priority patent/GB558578A/en
Application granted granted Critical
Publication of US2384931A publication Critical patent/US2384931A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N17/00—Diagnosis, testing or measuring for television systems or their details
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/04—Synchronising
    • H04N5/06—Generation of synchronising signals

Definitions

  • a cathode-ray tube of the builtin type is provided for monitoring, and both horizontal and vertical linearity test bars forthe Pattern are made available.
  • This invention relates to the production of. sweep and blanking signals for iconoscopes, blanking pedestals for Video amplifiers, ⁇ and corn- ⁇ posite super-synchronizing signals. Sweep voltages are also supplied to auxiliary equipment, and test signals are supplied for checking sweep linearity.
  • a vacuum tube is caused to operate as a sine-Wave oscillator at twice the desired line scanning frequency for an iconoscope.
  • a second tube is caused to operate as a relaxation oscillator and is synchronized by the sine Wave of the first tube so as to produce a pulse at the frequency of this sine wave, which frequency will be called the master .frequencyi
  • This pulse of master frequency is used to synchronize another vacuum tube oscillator at half the frequency, thus producing a pulse at the desired line frequency.
  • the pulse at line frequency is used as a driving ⁇ pulse for producing sawtooth wave forms as wellas wave forms for super-synchronizing.
  • The: pulse at master frequency is also used to syn-Y chronize a chain of relaxation type oscillators for the purpose of dividing the master frequency down to the desired field scanningV frequency.
  • the pulse at field frequency is used to produce sawtooth sweep wave forms and also wave forms for super-synchronizing.
  • Control tubes interlock the field frequency and power-line frequency to4 the master sine-wave oscillator to keepit at the proper frequency.
  • the time constants of the oscillator circuits can be quickly changedVA by switching arrangements so that the impedances of circuitsare readily varied to provide the desired frequencies.
  • pulses can be introduced into the super-synchronizing circuits so that' the horizontal and vertical sweep wave forms, can be readily tested for linearity, determining camera linearity and receiver linearity independently.
  • cathode-ray tube for observing the various wave'isf vforms is built in the-generator, with a switch which selects the signal or Wave form to be observed as well as the proper sweep frequency time base for the ⁇ respective signals.
  • Fig. 1 shows a master pulse generator in which the frequency can be changed
  • Fig. 2 shows a pulse generator from which a line frequency pulse suitable for television may showingfhow linearity test signals may be generated
  • Fig. 4 shows the pattern on a television receiver illustrating the linearity test.
  • reference character I indicates a wire leading from a sine-wave generator to the transformer 2 of the relaxation oscillator 24 to synchronizev the oscillator 25.
  • One end of the primary 3 is connected through load resistor 4 to ground and the other end is connected through condenser 5 to grid 6 of the oscillator tube 1.
  • the small variableresistor I0 is to ⁇ adjust the frequency more closely when necessary.
  • the master pulse on I4 is applied to another relaxation oscillator 25 such as shown in Fig. 2.
  • V'I'hle pulse is applied to the primary I5 of the transformer I6'.
  • 'I'he time constants for this oscillator - which-depend upon the condenser I'I and the resistors I8 in series with the small adjustable resistor I9, are selected so that the frequency of this oscillator 20 is exactly half of the rst one when the master pulse from the first oscillator is applied to it.
  • a master sinewave oscillator 23 is shown as one which may generate a 31.5 kc. sine wave, for example.
  • is connected to it, which is in turn controlled by direct current from a lock-in circuit 22 connected to the field frequency pulse of 60 cycles.
  • the signal from the 31.5 kc. oscillator 23 which is at twice line frequency is applied to the master pulse oscillator 24, which is the oscillator shown in detail in Fig. 1.
  • the signal from the master pulse oscillator 24 is applied to the oscillator 25, which is shown in detail in Fig. 2, where theY frequency is halved, and is the present standard 15,750 cycles per second, or 525 lines per frame for television line scanning.
  • the frequency of the signal from the master pulse oscillator 24 is divided 1, 5, 5 and 3 as indicated at 30, 3
  • the resistances such as resistances 9 (Fig. l) will be inserted in accordance with the frequency of the input signal at At the same time the resistances I8 (Fig. 2) and all-the other corresponding resistances in the oscillators indicated in Fig. 3 at 23, 24, 25, 30, 3
  • 'Ihese blocks indicate oscillators similar to those shown in Figs. 1 and 2.
  • switches 8 and 8' and corresponding switches at the other oscillators indicated in Fig. 3 are connected together or ganged as indicated by the dotted line L (Figs. 1 and 2) so that they will be moved correspondingly and simultaneously, thus providing the needed time constants for the respective oscillators at all times.
  • pulses at other frequencies such as 441 lines at 30 frames per second or 625 lines at l frames per second, for example, can be obtained.
  • the following table shows suitable data for practical cases:
  • the switching arrangements shown in Figs. 1 and 2 can be safely utilized for quickly changing to different scan-4 ning frequencies over a wide range.
  • the resistors 9, shown connected in by the switch 8 may be of such size that the master pulse frequency on leads
  • lead 45 connects from oscillator 25 to a carrier generator 4
  • a lead 43 connects the generator 4
  • a lead 45. also connects fromv oscillator 33 to keying tube 44.
  • a lead 46 connects keying tube 44 to the mixer 4l so that the frequencies of the oscillators 3
  • Switch 48'and resistance 49 are for partly short-circuiting the keying tube 44, thus allowing the signal from generator 4
  • the mixer 4? is also adapted to another type of signal so that when the switch 52 is closed a signal is introduced from the divider stage 3
  • consists of two multiplier stages which increase .the line frequency pulses from box 25 to an exact harmonic which in the case illustrated is the 34thV harmonic.
  • the strong signals will occur at 900 C. P. S. or once for every 35th oscillation (1/7 of 1/5 of 31.5 kc. in the case illustrated) of the master pulse oscillator 24.
  • will occur five times as often, or at 1/7 of 31.5 kc., or 4500 C. P. S.
  • the master pulse oscillator 24 is assumed to be running at 31.5 kilocycles.
  • a first divider stage 30l divides this frequency by a factor of 'l and the second divider stage 3
  • divides further by a factor of 5. Since the divider 25 which delivers the line frequency pulses operates at half the frequency of the master oscillator 24, the master oscillator 24applies impulses at every half line of scanning. Therefore the 4500 C. P. S. impulses which are fed to wire 54 by the synchronizing action of,- box 30 places impulses every 'th half line of scanning, since the linefnscanning frequency 15,750+4500 1/2 of '7, ⁇
  • reference character 56 represents the horizontal dimension of a received television picture which is four units wide in comparison with the vertical dimension 51 which is three units high.
  • the receiving tube may either have a picture upon which the linearity test calibrations are superposed, or the transmitter may be sending an artificial white ileld upon which the linearity test calibrations appear visibly.
  • Closing of the switch 48 introduces on'the pattern of Fig. 4 the 34th harmonic 535.5 kc., for example, of the line frequency 15.75 kc. This results in the dark vertical stripes 59 separated by the light vertical stripes 60. Approximately 30 of these dark vertical stripes 59 would be visible across the pattern since the remaining 4 occur on the return trace which is blanked out. in time, they would appear uniformly spaced n the vreceiving screen only when the horizontal linearity is correct. Thus the receiver scanning may be checked for linearity and may be adjusted by use of these bars or stripes 59.
  • reference character 62 indicates a linearity calibration down the center of the picture which will be introduced bythe closing of switch 52 of Fig. 3.
  • This calibration appears as a series of fine lines every fifth one of which is introduced as shown at 66 as a heavy line due to the dividing action of 5:1 between boxes 30 and 3l of Fig. 3, in the particular example illustrating this invention.
  • any combination of line and field scanning there will be at the box 3l of Fig. 3 a signal available to give evenly spaced indicating calibrations. 'Iime can therefore be used for checking vertical linearity and if the vertical scanning, for example, tends to be slower at the top than in the middle these calibration marks would appear to be packed at the top.
  • an oscillator for generating a, predetermined frequency, means to control said frequency, a series of frequency dividers connected to said oscillator, and means to obtain a composite signal from said oscillator and one of said frequency dividers in which a mixer is provided for said composite signal, a keying tube is provided between said oscillator and said mixer, and a switch and by-pass resistance is provided across said keying tube.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • General Health & Medical Sciences (AREA)
  • Testing, Inspecting, Measuring Of Stereoscopic Televisions And Televisions (AREA)
US426695A 1942-01-14 1942-01-14 Synchronizing generator Expired - Lifetime US2384931A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE463823D BE463823A (US07816562-20101019-C00012.png) 1942-01-14
US426695A US2384931A (en) 1942-01-14 1942-01-14 Synchronizing generator
GB379/43A GB558578A (en) 1942-01-14 1943-01-08 Synchronizing generators

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US426695A US2384931A (en) 1942-01-14 1942-01-14 Synchronizing generator

Publications (1)

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US2384931A true US2384931A (en) 1945-09-18

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US426695A Expired - Lifetime US2384931A (en) 1942-01-14 1942-01-14 Synchronizing generator

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US (1) US2384931A (US07816562-20101019-C00012.png)
BE (1) BE463823A (US07816562-20101019-C00012.png)
GB (1) GB558578A (US07816562-20101019-C00012.png)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2485101A (en) * 1944-12-30 1949-10-18 Raytheon Mfg Co Pulse generator
US2509792A (en) * 1946-05-17 1950-05-30 Raytheon Mfg Co Blocking oscillator trigger circuit
US2591600A (en) * 1948-11-26 1952-04-01 Washington Inst Of Technology Radiosonde calibration method
US2647426A (en) * 1948-03-31 1953-08-04 William F Battle Electrically operated musical instrument
US2677059A (en) * 1951-03-06 1954-04-27 Rca Corp Signal generator

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2593842A (en) * 1947-08-13 1952-04-22 Du Mont Allen B Lab Inc Phase discriminator

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2485101A (en) * 1944-12-30 1949-10-18 Raytheon Mfg Co Pulse generator
US2509792A (en) * 1946-05-17 1950-05-30 Raytheon Mfg Co Blocking oscillator trigger circuit
US2647426A (en) * 1948-03-31 1953-08-04 William F Battle Electrically operated musical instrument
US2591600A (en) * 1948-11-26 1952-04-01 Washington Inst Of Technology Radiosonde calibration method
US2677059A (en) * 1951-03-06 1954-04-27 Rca Corp Signal generator

Also Published As

Publication number Publication date
BE463823A (US07816562-20101019-C00012.png)
GB558578A (en) 1944-01-11

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