GB779019A - Improvements in or relating to carrier-wave transmission systems for television signals - Google Patents

Improvements in or relating to carrier-wave transmission systems for television signals

Info

Publication number
GB779019A
GB779019A GB31666/54A GB3166654A GB779019A GB 779019 A GB779019 A GB 779019A GB 31666/54 A GB31666/54 A GB 31666/54A GB 3166654 A GB3166654 A GB 3166654A GB 779019 A GB779019 A GB 779019A
Authority
GB
United Kingdom
Prior art keywords
subcarrier
modulation
main carrier
frequency
amplitude
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
Application number
GB31666/54A
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.)
Koninklijke Philips NV
Original Assignee
Philips Gloeilampenfabrieken NV
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 Philips Gloeilampenfabrieken NV filed Critical Philips Gloeilampenfabrieken NV
Publication of GB779019A publication Critical patent/GB779019A/en
Expired legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04JMULTIPLEX COMMUNICATION
    • H04J9/00Multiplex systems in which each channel is represented by a different type of modulation of the carrier
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00Television systems
    • H04N7/08Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00Details of colour television systems

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Television Systems (AREA)

Abstract

779,019. Multiplex radio signalling. NAAMLOOZE VENNOOTSCHAP PHILIPS GLOEILAMPENFABRIEKEN. Nov. 2. 1954 [Nov. 5, 1953], No. 31666/54. Class 40(5) In a television system two video signals # 1 , # 2 corrected to avoid cross - modulation as in Specification 776,989 modulate respectively the positive and negative half cycles of a subcarrier in turn modulating a main carrier, so that to zero values of the subcarrier there corresponds a predetermined amplitude γ of the main carrier greater than the maximum amplitude A\ of the negative half cycles of the subcarrier. To this end # 1 , # 2 after correction may be separately multiplied by (1 + 2 cos w 0 t) and (1 - 2 cos w 0 t) where w 0 is the angular frequency of the subcarrier, then the outputs filtered to lie within a frequency band with upper angular frequency w 0 , i.e. the filtered products are then respectively # 1 + # 1 (transposed to the subcarrier frequency) and # 2 - # 2 (transposed to the subcarrier frequency). The difference of the two filtered products is then taken and is therefore such that during alternate half cycles of the subcarrier frequency the maximum amplitudes of the subcarrier are # 1 and # 2 respectively so that detecting alternate peaks of the subcarrier give # 1 and # 2 . This composite subcarrier signal (difference of the above filtered products) then modulates the main carrier to a depth subject to the aforesaid restriction (to avoid distortion due to over-modulation). Pulses of amplitude Œγ in synchronism with the. line or frame sync pulses A 9 of the two video signals, or one of them may be inserted in the composite subcarrier during instants of zero amplitude by diode or other circuits to fix the modulation level of the subcarrier but are preferably removed during modulation of the main carrier. The lower level modulation # 2 , (Fig. 2a) of the main carrier may be displayed on a cathode ray tube and the modulation depth thereby corrected manually or automatically by a, photo-electric cell coacting with an apertured mask on the screen. At the receiver the upper level # 1 and lower # 2 (Fig. 2a) modulation are separated by threshold diode circuits reversely connected in parallel.
GB31666/54A 1953-11-05 1954-11-02 Improvements in or relating to carrier-wave transmission systems for television signals Expired GB779019A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR1013691X 1953-11-05

Publications (1)

Publication Number Publication Date
GB779019A true GB779019A (en) 1957-07-17

Family

ID=9571805

Family Applications (1)

Application Number Title Priority Date Filing Date
GB31666/54A Expired GB779019A (en) 1953-11-05 1954-11-02 Improvements in or relating to carrier-wave transmission systems for television signals

Country Status (4)

Country Link
BE (1) BE533099A (en)
DE (1) DE1013691B (en)
FR (1) FR1093546A (en)
GB (1) GB779019A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2118806A (en) * 1982-04-22 1983-11-02 Elliott Bros Communication system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1227526B (en) * 1959-03-11 1966-10-27 Loewe Opta Gmbh FM transmission system for two low-frequency signals on a common high-frequency carrier

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2118806A (en) * 1982-04-22 1983-11-02 Elliott Bros Communication system
US4519067A (en) * 1982-04-22 1985-05-21 Marconi Avionics Limited Communication system providing amplifier gain by half-cycle carrier signal control

Also Published As

Publication number Publication date
FR1093546A (en) 1955-05-05
DE1013691B (en) 1957-08-14
BE533099A (en)

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