US2515619A - Device for stereophonic transmission of signals by electric means - Google Patents

Device for stereophonic transmission of signals by electric means Download PDF

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Publication number
US2515619A
US2515619A US685121A US68512146A US2515619A US 2515619 A US2515619 A US 2515619A US 685121 A US685121 A US 685121A US 68512146 A US68512146 A US 68512146A US 2515619 A US2515619 A US 2515619A
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signals
frequency
carrier wave
auxiliary carrier
signal
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US685121A
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English (en)
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Weyers Theodorus Josephus
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Hartford National Bank and Trust Co
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Hartford National Bank and Trust Co
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/86—Arrangements characterised by the broadcast information itself
    • H04H20/88—Stereophonic broadcast systems

Definitions

  • FILTER 2 6 17150001115 JOSEPHUS MEWS IN VEN TOR.
  • This invention relates to a device for stereophonic transmission by electrical means with the use of a common channel for the two stereophonic signals.
  • I phonic transmission It has been proposed in I phonic transmission to transmit the two different sound signals via a common channel and one of the sound signals as the lower sideband of an auxiliary carrier wave.
  • the frequency of the auxiliary carrier wave may be chosen so as to be so high that the lowest frequency of the lower sideband' exceeds the highest frequency of the other sound signal. It has also been proposed to transmit-the two stereophonic signals as the two sidebands of the carrier'wave.
  • the invention has for'its object to reduce the width of the channel for the transmission of stereo-phonic signals. According to the invention, this object is attained -'by the suppression of the highest and the lowest frequencies of one 1.
  • the invention is based on recognition of the fact that for the s-tereophonic transmission of signals it is not essential to transmit stereophonically the highest and the lowest acoustic frequencies.
  • Figs. 1a and 1b are graphs illustrative of the theory underlying the invention.
  • Fig. 2 shows schematically a pref'erredw embodiment of a receiving circuit ,in accordance with the invention.
  • Fig. 3 is a block diagram of a transmitting and receiving systemsinziaccordance the invention.
  • Fig. 1 makes it clear .that the aforesaid-method permits .of reducing the total width of the -common channel.
  • auxiliary carrier wave having a frequency :of 35,000 c./s. and if the frequency-spectrum 'of' the twosound signals extends from 50 to 15,000 c./s.
  • the channel shown in Fig 1a is set up.
  • the band (1 represents the frequency-spectrum of one signal, the bands I) and b1 the lower and the upper sidebands of the auxiliary carrier wave modulated 3 Claims. (01. 179-1) 2 by the other signal.
  • the total width B of the common channel for the stereophonic reproduction is, consequently, about 35,000 c./s. If, however, according to the invention, the highest and lowest frequencies of the signal transmitted as the lower sideband are suppressed, for instance the frequencies above 5000 and below 300 c./s., a width of the common channel of about 25,000 'c./s. will suffice, as is shown in Fig. 11), again under the assumption that the upper sideband is suppressed.
  • the spacing between the bands a and b (viz 5000 c./s.) is chosen to be as large as in the case of Fig. 1a,.
  • An additional advantage of the device according to the invention is further that the selectivity requirements of the filter by means of which the upper sideband is suppressed need not he so severe, the frequency-difference between the highest frequency of the lower sideband and the lowest frequency to be suppressed of the upper sideband having increased materially, viz. flOl'i'l c./s. in the case of Fig. 1a to 600 as.
  • the common channel' which consequently contains the frequencyband: of one signal and the lower sideband of the auxiliary carrier wave modulated by the other signal as well as this auxiliary carrier wave frequency, may be modulated on the carrier wave of a transmitter. This modulation of the carrier wave by the channel may be effected in amplitude equally well as in frequency.
  • amplitude or frequency modulation to reduce the amplitude of the auxiliary carrier wave.
  • This can be secured by means of the same filter as that which. suppresses the upper sideband.
  • the stereophonic signalstransmitted by means of a' device according to the invention can be reproduced by means of a device as shown in Fig. 2.
  • the latter comprises two channels, one channel I for the reproduction of the signal I) transmitted as the lower sideband of the auxiliary carrier wave (Fig.
  • the electrical oscillations received are rectified by a detector device I which comprises an oscillatory circuit 2 tuned to the carrier wave of the transmitter and are fed via a potentiometer 3 to the two channels of the receiving device.
  • the channel II is constituted by a low-frequency amplifying device comprising two amplifying tubes 4 and 5.
  • a loudspeaker 6 is provided on the output side.
  • the low-frequency oscillations from 50 to 15,000 c./s. are amplified in this channel.
  • the electrical oscillations having higher frequencies are consequently suppressed in this channel.
  • the oscillations are supplied via an amplifying tube 7 to a selective oscillatory circuit 8 tuned to the auxiliary carrier wave.
  • the oscillatory circuit 8 is followed by a detector l comprising a potentiometer H, from which the low-frequency signal whose lowest frequencies (below 300 c./s.) and highest frequencies (above 5000 c./s.) fail, can be obtained. In so far as the other signal is not suppressed by the oscillatory circuit (whose highest frequency is lower by 5000 c./s.
  • the output amplifying tube 13 is followed by a loudspeaker M which reproduces the signal whose highest and lowest frequencies fail.
  • Fig. 3 Apparatus for carrying out the stereophonic transmitting technique set forth in connection with Fig. 1b is illustrated in Fig. 3 wherein blocks and 2
  • the frequencies of signal 1) below 300 and above 5000 cycles are suppressed by a bandpass filter 22, and the resultant 300-5000 cycle band is combined in a modulator v23 with a 25,000 cycle oscillation from an auxiliary carrier source 24.
  • the upper side band (25,300-30,000 cycles) yielded by modulator 23 is discriminated against by a filter 25 which accommodates only the lower side band (20,000 to 24,700 cycles) and the 25,000 cycle auxiliary carrier.
  • the output of filter 25 and the output of signal source 20 are fed to a modulator 26 where they are imposed on a main carrier from a source 21 and then transmitted by means of a transmitter 28.
  • Apparatus for transmitting via a common channel first and second stereophonic sound signals having the same frequency spectrum com- 4 prising means for suppressing the upper and lower portions in the frequency spectrum of said first sound signals, an auxiliary carrier wave source, means for modulating said auxiliary carrier wave with the remaining first sound signals to produce output signals having upper and lower sidebands, means for suppressing the upper sideband in said output signals, and means for applying said second sound signals and the remaining output signals as an input to said common channel, the frequency of said auxiliary carrier wave having a value such that said remaining output signals are spaced from said second sound signals in said common channel.
  • Apparatus for transmitting via a common channel first and second stereophonic sound signals having the same frequency spectrum comprising means for suppressing the upper and lower portions in the frequency spectrum of said first sound signals, an auxiliary carrier wave source, means for modulating said auxiliary carrier wave withthe remaining first sound signals to produce output signals having upper and lower sidebands and an auxiliary carrier wave component, means for suppressing said upper sideband and partially suppressing said carrier wave component in said output signals, and means for applying said second sound signals and the remaining output signals as an input to said common channel, the frequency of said auxiliary carrier wave having a value such that said remaining output signals are spaced from said second sound signals in said common channel.
  • a stereophonic system comprising a carrier wave source, apparatus for transmitting via a common channel first and second stereophonic sound signals having the same frequency spectrum including means for suppressing the upper and lower portions in the frequency spectrum of said'first sound signals, an auxiliary carrier wave source, means for modulating said auxiliary carrier wave with the remaining first sound signals to produce output signals having upper and lower sidebands, means for suppressing the upper sideband in said output signals and means for applying said second sound signals and the res maining output signals as an input to said common channel, the frequency of said auxiliary carrier wave having a value such that said remaining output signals-are spaced from said second sound signals in said common channel, and means for modulating said carrier wave with the signals appearing in said common channel.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Stereophonic System (AREA)
US685121A 1943-04-21 1946-07-20 Device for stereophonic transmission of signals by electric means Expired - Lifetime US2515619A (en)

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NL245731X 1943-04-21

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US2515619A true US2515619A (en) 1950-07-18

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US (1) US2515619A (en(2012))
BE (1) BE455396A (en(2012))
CH (1) CH245731A (en(2012))
FR (1) FR903556A (en(2012))
GB (1) GB622255A (en(2012))

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2862056A (en) * 1954-06-22 1958-11-25 Westinghouse Electric Corp Radio communication system
US2961615A (en) * 1959-08-18 1960-11-22 Rca Corp High-level modulated signal amplifier system
US3122610A (en) * 1960-07-22 1964-02-25 Gen Electric Circuitry for multiplex transmission of fm stereo signals with pilot signal
US3152224A (en) * 1962-08-01 1964-10-06 Zenith Radio Corp F. m. stereophonic multiplex receiver having a single volume control for adjusting the magnitude of the signals presented to the stereo detector and the output materixing means
US3257512A (en) * 1960-04-18 1966-06-21 Zenith Radio Corp Stereo fm transmission system
US4074084A (en) * 1975-11-05 1978-02-14 Berg Johannes C M Van Den Method and apparatus for receiving sound intended for stereophonic reproduction
US6658115B1 (en) * 1999-11-16 2003-12-02 Radioshack, Corp. Method and apparatus for high fidelity wireless stereophonic transmission

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1717064A (en) * 1925-10-20 1929-06-11 Western Electric Co Electric-wave transmission system
US1797317A (en) * 1928-12-20 1931-03-24 American Telephone & Telegraph Binaural phase-discrimination radio system
US1854247A (en) * 1928-10-30 1932-04-19 American Telephone & Telegraph Multiplex phase discrimination transmission system
US2019615A (en) * 1933-11-21 1935-11-05 Electrical Res Prod Inc Sound transmission system
US2098561A (en) * 1934-02-09 1937-11-09 Rca Corp System for producing stereosonic effects
US2114019A (en) * 1934-04-26 1938-04-12 Western Electric Co Sound reproducing system
US2137032A (en) * 1936-09-30 1938-11-15 Bell Telephone Labor Inc Sound reproducing system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1717064A (en) * 1925-10-20 1929-06-11 Western Electric Co Electric-wave transmission system
US1854247A (en) * 1928-10-30 1932-04-19 American Telephone & Telegraph Multiplex phase discrimination transmission system
US1797317A (en) * 1928-12-20 1931-03-24 American Telephone & Telegraph Binaural phase-discrimination radio system
US2019615A (en) * 1933-11-21 1935-11-05 Electrical Res Prod Inc Sound transmission system
US2098561A (en) * 1934-02-09 1937-11-09 Rca Corp System for producing stereosonic effects
US2114019A (en) * 1934-04-26 1938-04-12 Western Electric Co Sound reproducing system
US2137032A (en) * 1936-09-30 1938-11-15 Bell Telephone Labor Inc Sound reproducing system

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2862056A (en) * 1954-06-22 1958-11-25 Westinghouse Electric Corp Radio communication system
US2961615A (en) * 1959-08-18 1960-11-22 Rca Corp High-level modulated signal amplifier system
US3257512A (en) * 1960-04-18 1966-06-21 Zenith Radio Corp Stereo fm transmission system
US3122610A (en) * 1960-07-22 1964-02-25 Gen Electric Circuitry for multiplex transmission of fm stereo signals with pilot signal
US3152224A (en) * 1962-08-01 1964-10-06 Zenith Radio Corp F. m. stereophonic multiplex receiver having a single volume control for adjusting the magnitude of the signals presented to the stereo detector and the output materixing means
US4074084A (en) * 1975-11-05 1978-02-14 Berg Johannes C M Van Den Method and apparatus for receiving sound intended for stereophonic reproduction
US6658115B1 (en) * 1999-11-16 2003-12-02 Radioshack, Corp. Method and apparatus for high fidelity wireless stereophonic transmission

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Publication number Publication date
GB622255A (en) 1949-04-28
CH245731A (de) 1946-11-30
BE455396A (en(2012))
FR903556A (fr) 1945-10-09

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