US2144776A - Synchronization method for television - Google Patents

Synchronization method for television Download PDF

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Publication number
US2144776A
US2144776A US13681A US1368135A US2144776A US 2144776 A US2144776 A US 2144776A US 13681 A US13681 A US 13681A US 1368135 A US1368135 A US 1368135A US 2144776 A US2144776 A US 2144776A
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US
United States
Prior art keywords
sound
frequency
image
carrier frequencies
line
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
US13681A
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English (en)
Inventor
Schlesinger Kurt
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Loewe Opta GmbH
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Loewe Opta GmbH
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
Application filed by Loewe Opta GmbH filed Critical Loewe Opta GmbH
Application granted granted Critical
Publication of US2144776A publication Critical patent/US2144776A/en
Anticipated expiration legal-status Critical
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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
    • H04N5/06—Generation of synchronising signals
    • H04N5/067—Arrangements or circuits at the transmitter end
    • H04N5/073—Arrangements or circuits at the transmitter end for mutually locking plural sources of synchronising signals, e.g. studios or relay stations

Definitions

  • this line frequency amounts to 4500 periods, so that as control tone a tone of 9000 or 13,500 periods is concerned, which does not interfere with the sound reception.
  • this tone is separated by tuned circuits from the speech frequency band, and conducted as synchronizing frequency to a relaxation apparatus, which in certain, connections allows automatically the passage of every second or third alternation and oscillates in synchronized fashion with the desired reduced relaxation frequency.
  • the simultaneous distant control of the low image-change oscillation (25j periods) meets according to the known method with the difculty that a corresponding, low control tone of or 25 periods interferes considerably with the reception of the sound or with the unsteadiness of the mains always present in the apparatus.
  • the subject matter of the present invention is the idea of dispensing entirely with the transmission of a special control tone for the low relaxation frequency, and to derive the signals necessary in this connection from the 9000-period tone by the fact that this tone upon each change of image is interrupted at the transmitter for a brief space of time, whilst at the receiver the previously mentioned selection circuit for this tone is connected with a rectifier.
  • the directional current taken from this rectifier accordingly remains constant during the entire image, and only changes whenthe control tone is briefly cut off. From the current, therefore, of this special rectier according to the invention there may be 0btained the synchronization potential for the image-change relaxation apparatus, Whilst the synchronization for the line-relaxation apparatus may be tapped in direct fashion from the tone circuit itself.
  • the television transmission apparatus comprises two, preferably ultra-short wave transmitters, of which the one is modulated only -with the contents of the picture, Whilst the other is modulated with the accom- Danying text and also with the middle-frequency control tone.
  • the frequency of the latter is.an integral multiple of the line frequency.
  • the contrl tone is interrupted at the transmitter upon each change of image.
  • At the receiver there is preferably employedwhich is of great advantage in the performance of this method a duplex connection system as already described previously by the applicant, which system is characterized by the fact that a single local oscillator has the two transmission waves heterodyned thereon simultaneously, whereby two different beat frequencies are produced.
  • the beat frequency of the image (of the order of 200 m.) is separated from the beat frequency of the sound transmitter (of the order of i000 m.).
  • the latter is demcdulated by a rectier and amplied in respect of low frequency. In this manner there is heard the accompanying text, and in addition the intermittent control tone is available.
  • the latter in accordance with the invention, is conducted to a sound selection circuit, which is connected With a special rectier. At the sound circuit the control potential for the line relaxation apparatus is tapped in direct fashion, whilst behind the sound circuit rectifier the control potential is available for the image apparatus.
  • the receiver in place of the receiver as described having a common local oscillator there may also be employed a receiving station having two separate receivers for the image wave and sound Wave.
  • the line frequency is produced cptiv produced in the manner known per se from the basic line frequency introduced a higher harmonic, which is filtered in the sound circuit IB tuned to twice or three times the line frequency.
  • a special device and in the most simple form for example a rotating cut-out I5', which may be operated synchronously for example by the filmadvancing means I I it is ensured in accordance with the invention that the control tone is interrupted once per image at the edge of the image.
  • Fig. 2 there is shown a receiver according to the duplex method.
  • the receiver possesses a common local oscillator I5 and a common aerial II. Both act inductively on a directional arnpliier I8, at the output of which, therefore, the two carrier waves pertaining to the two transmission waves may be tapped and separated simultaneously by two band filters I9 and 20.
  • the image is additionally passed through the medium of the image receiver 2l to the television tube 22, the carrier wave for the tone at first passes to a first rectifier 23. Following thereon it is amplified in the low-frequency amplifier 24 and conducted to the loudspeaker 25.
  • the control tone may accordingly again be recovered, whilst the same remains inaudible in the loudspeaker, on the one hand on account of its high pitch and on the other hand owing to the bridging condenser 21.
  • the terminal 28 may be connected with the sound circuit 26 either direct or through the medium of a potential distributing means, and takes over the synchronization of the line relaxation apparatus in direct fashion.
  • the rectifier 29 according to the invention in the drawing a diode
  • which rectifier is linked up with a working resistance 30 and is connected through the medium of a condenser 3l with the terminal 32.
  • the terminal 32 may, therefore, be connected in direct fashion with the synchronization terminal of the image change relaxation apparatus.
  • a frequency-reducing connection of the kind known per se, which reduces the control frequency to the line frequency.
  • a frequency-reducing connection of the kind known per se, which reduces the control frequency to the line frequency.
  • the transmitter means for disconnecting the image current during the generation of the image change and, if desired, also the line change.
  • the amplifier 3 and the transmitter 4 means for example, a discharge tube
  • the line or image change are controlled by the line or image change and which, during the image change and if desired also the line change, short-circuit the connection line, which if desired may be positively biassed.
  • a pair of transmitters radiating two different carrier frequencies.
  • a pair of transmitters radiating two different carrier frequencies, means to modulate one of said carrier frequencies by the video signals and the second one by the sound frequencies and simultaneously by an ultra-audible frequency being an integral multiple of the line frequency and means to weaken said modulating multiple of the line frequency at each frame change.
  • a pair of transmitters radiating two different carrier frequencies, means to modulate one of said carrier frequencies by the video signals and the second one by the sound frequencies and simultaneously by the line frequency, and means to suppress completely said modulating line frequency during each frame change.
  • a pair of transmitters radiating two different carrier frequencies, means to modulate one of said carrier frequencies by the video signals and the second one by the sound frequencies and simultaneously by an ultra-audible frequency being an integral multiple of the line frequency, and means to suppress completely said modulating multiple of the line frequency during each frame change.
  • a pair of transmitters radiating two different carrier frequencies, means to modulate one of said carrier frequencies by the video signals and the second one by the sound frequencies and simultaneously by the line frequency, means to weaken said modulating line frequency at each frame change, and a receiver having means to secure automatically a correct reception of said video signals when said sound carrying frequency is correctly received.
  • a pair of transmitters radiating two different carrier frequencies, means to modulate one of said carrier frequencies by the video signals and the second one by the sound frequencies and simultaneously by an ultra-audible frequency being an integral multiple of the line frequency at each frame change, and a receiver having means to secure automatically a correct reception of said video signals when said sound carrying frequency is correctly received.
  • a pair of transmitters radiating two different carrier frequencies, means to modulate the first of said carrier frequencies by the video signals and the second one by the sound frequencies and simultaneously by the line frequency, and means to weaken said modulating line frequency at each frame change, said both carrier frequencies of the transmitter being not very different and the receiver being provided with a local oscillator of a frequency exactly in the middle between said carrierfrequencies.
  • a pair of transmitters radiating two different carrier frequencies
  • means 75 to modulate one of said carrier frequencies by the video signals and the second one by the sound frequencies and simultaneously by an ultra-audible frequency being an integral multiple of the line frequency at each frame change, said both carrier frequencies of the transmitter being not very different and the receiver being provided with a local oscillator of a frequency exactly in the middle between said carrier frequencies.
  • a pair of transmitters radiating two different carrier frequencies, means to modulate one of said carrier frequencies by the Video signals and the second one by the sound frequencies and simultaneously by the line frequency, means to weaken said modulating line frequency at each frame change, and a receiver provided with a lter arrangement separating the multiple of the line frequency, a rectifier for said frequency and means to control the frame relaxation oscillation by said rectied frequency.
  • a transmitter radiating two different carrier frequencies, means to modulate the rst of said carrier frequencies by the video signals and the second one by the sound frequencies and at once by an ultra-audible frequency being an integral multiple of the line frequency at each frame change, and a receiver provided with a filter arrangement separating the multiple of the line frequency, a rectifier for said frequency and means to control the frame relaxation oscillation by said rectified frequency.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Television Receiver Circuits (AREA)
  • Radio Relay Systems (AREA)
US13681A 1934-03-31 1935-03-29 Synchronization method for television Expired - Lifetime US2144776A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE442333X 1934-03-31

Publications (1)

Publication Number Publication Date
US2144776A true US2144776A (en) 1939-01-24

Family

ID=6522163

Family Applications (1)

Application Number Title Priority Date Filing Date
US13681A Expired - Lifetime US2144776A (en) 1934-03-31 1935-03-29 Synchronization method for television

Country Status (3)

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US (1) US2144776A (fr)
FR (1) FR788076A (fr)
GB (1) GB442333A (fr)

Also Published As

Publication number Publication date
GB442333A (en) 1936-02-06
FR788076A (fr) 1935-10-03

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