US2270652A - Radio-receiving apparatus - Google Patents

Radio-receiving apparatus Download PDF

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Publication number
US2270652A
US2270652A US285832A US28583239A US2270652A US 2270652 A US2270652 A US 2270652A US 285832 A US285832 A US 285832A US 28583239 A US28583239 A US 28583239A US 2270652 A US2270652 A US 2270652A
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United States
Prior art keywords
frequency
broadcast
sound
changer
signals
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Expired - Lifetime
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US285832A
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English (en)
Inventor
Espley Dennis Clark
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General Electric Company PLC
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General Electric Company PLC
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Publication date
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Publication of US2270652A publication Critical patent/US2270652A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/60—Receiver circuitry for the reception of television signals according to analogue transmission standards for the sound signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/16—Circuits
    • H04B1/26—Circuits for superheterodyne receivers

Definitions

  • This invention relates to radio-receiving apparatus lof the type adapted to receive alternatively broadcast sound signals and television signals accompanied by sound, and comprising a frequency changer common to both the vision channel and the channel of the sound signals accompanying the television signals.
  • sound signals accompanying the television signals will be called simply sound, while the broadcastsound signals will be called broadcast.
  • apparatus of this type it is desirable on the grounds of economy to use the 'same ultimate receiver, usually a loudspeaker, for reproducing both the sound and the broadcast. It would be desirable on the same grounds to make other elements common to the lsoundand the broadcast-channels, if this could be done without loss in the quality of the reproduced signals. But there are certain difiiculties, about to'be discussed, in making many elements common.
  • the object of this invention is to provide circuit arrangements, in which many elements are common to the sound and broadcast channels, giving high quality of the reproduced signals.
  • the carrier frequencies of the vision, sound, short, medium, and long-broadcast are respectively 45, 41.5, 20-6, 1.5-0.55, and 0.330.15 mc. Broadcast carrier frequencies of neighbouring stations may diner by Aas little as 0.009 mc.; accordingly there must precede the final audio-frequency detector frequency selective means capable of distinguishing frequencies separated by such small dilferences.
  • the width of the vision band of frequencies is so great that the intermediate frequency (I.
  • F. resulting from the frequency-changer common to both sound and vision must be at least several mc.
  • f is the mean frequency transmitted preferentially by frequency-selective means of the ordinary kind, namely those tuned by inductance and capacity, and if f is the smallest difference in frequency that they are adapted to distinguish, f in general increases with f; if f is several mc., f is usually much greater than 0.009 mc.
  • the broadcast carrier or a carrier resulting from the combination of that carrier with local oscillators of frequency fo, is applied to the input of the frequencychanger common to the vision and sound channels (whereb-y the desired economy of parts is achieved), and frequency-selective means, capable of distinguishing the frequencies of neighbouring broadcast stations, are introduced into the broadcast channel in such a way that they do not restrict the breadth of the band of frequencies that can pass along the common part of the sound and vision channels (whereby the necessary selectivity is achieved). It will be pointed out later that the said frequencychanger need not act as such when the said carrier is applied to it.
  • the means may be introduced into this part ⁇ when the transference from television to broadcast reception takes place.
  • the part previously traversed by the sound signals may be modified, when the said transference takes place, so that this part becomes much more selective than before.
  • two branches A and B proceed from a common aerial I. They are adapt'- ed to be rendered alternatively operative, so that A is operative when television is to be received and B when broadcast is to be received.
  • the means by which they are rendered alternatively operative form no part of this invention, and many suitable means will occur to those skilled in the art. But it may be recorded that two means, or some combination of them, have been found especially convenient.
  • One is to arrange the supplies to the various parts of the set so that, by a suitable switch, power can be supplied to the broadcast portion but not to the sound portion or vice versa.
  • the other is to provide means for biasing valves, such as those in the amplifier 2 or the frequency change I2, so as to paralyse one or the other.
  • the means is representedby a two-way switch I8.
  • Branch A leads to the R. F. amplifier 2; thence to the frequency changer 3, fed by the local oscillator 4 generating 35 mc.; andthence to the I. F. amplifier 5. From here the sound and vision channels diverge, being separated by frequency selective means. The sound channel passes through the I. F. amplifier' 6 and through detector and audio-frequency amplifier 'I to the loud-speaker 8; the vision channelthrough the I. F. ampliners 9, I and the second detector II to the cathode ray tube I4. For simplicity the elements I, 3, I0, II, I4 are shown only in Figure l.
  • Branch B leads to the frequencychanger I2 fed by a local oscillator I3. The frequency-changer I2 may be preceded by a R. F. amplifier (not shown).
  • each frequency-changer and its local oscillator may be embodied in a single valve of known type, e. g. a triode-hexode. All this is standard practice.
  • the output of frequency-changer I2 is applied to the input of frequency-changer 3. From this point the four arrangements diverge.
  • the frequency of the local oscillator I3 is so adjusted in known manner to the frequency of the broadcast carrier that the I. F. resulting from the frequency-changer I2 is 28.5 mc., (or even 41.5 mc.), so that an I. F. of 6.5 mc. isl produced by the frequency-changer 3.
  • Further sharply-tuned frequency selective means I are either permanently at I5a in the lead between I, 2, and 3 (proposal (a) aforesaid), or introduced, when branch B is operative, at I5b in the sound channel anywhere between 3 and l, for example, between 5 and 6 as shownin Fig. (proposal (b) aforesaid); these means transmit a narrow frequency band, some 0.009 mc. wide, centred near 28.5 mc. (or 41.5 m0,), ⁇ if the means are at I5a, or near 6.5 mc., if the meansare at I5b.
  • the means I5 may be a crystal-tuned filter, which has the necessary selectively.
  • Method (b3) aforesaid is not applicable, because both the broadcast and the sound are conveyed by the same carrier along the path common to them.
  • Proposal b has lthe advantage that f/f is less, but arrangements (switch 2'I in Figure 1a) for introducing filters I5 or modifying existing filters have to be ganged with the switch (or equivalent) selecting A or B by any suitable means well known to the art, as for example the ganging bar 28 schematically illustrated in Fig. 1a. All forms of this embodiment have the drawback that the frequencies of the local generators 4 and 3 have to be very accurately constant. Further a frequency-changer generating an I. F. as high as 28.5 mc., though possible is outside normal prac'- tice and adds to the expense.
  • the frequency changer l2 produces an I. F. such as is used in ordinary broadcasting sets, namely about 0.5 mc.
  • the alternative usual broadcasting I. F. namely about 0.1 mc., is possible, though less suitable.
  • the frequency selective means I5 according to the invention can be I. F. lters such as are used in such sets, permanently situated at I5a; crystal filters are not required.
  • Shortwave broadcast carriers are to be received, is that fo, or some harmonic of it, is likely to lie in the band of these carriers; this is known to be undesirable.
  • the local oscillator 4 is suppressed by manipulation of a switch 33.
  • the frequency changer I2 must now give an I. F. 6.5 mc.; the stage 3, no longer a frequency changer, can be used as an amplifier.
  • the modification of the stage 3 from a frequency changer to an amplifier can be accomplished by any means well Aknown to the art, as for example changing the bias of the stage by manipulation of a switch 34 adapted to contact either of the points 35 or 36, said points having different potentials impressed thereon.”
  • the switches I8, 33 and 34 are all ganged vfor simultaneous operation, as schematically illustrated by the gauging bar 31 in Fig. 3. But the frequency-selective means I5a must be highly selective; for f/f is large, though not so condensers I6, I1.
  • Frequency changer I2 produces an I. F. about 0.5 mc.; when B is selected, the local oscillator 4 is suppressed; and the frequency selective means are introduced according to alternative b aforesaid.
  • Method (b2) or (b3) is preferably adopted.
  • the frequency-selective means I5 are provided by changing the frequency to which the frequency-selective means already present in the sound path are tuned. These means usually consist, at least in part, of couplings between the frequency changer 3, and the I. F. ampliers 5 and S.
  • branch A When branch A is selected, they must transmit preferentially.frequencies near 6.5 mc. (Those, if any, that are common to the sound and vision channels must also transmit the vision I. F. preferentially.)
  • branch B When branch B is selected, they must transmit preferentially a range of some 0.009 mc. near 0.5 mc.
  • the range of their transmission can be lowered by the introduction of the Said condensors IS and I'I may be introduced into the circuit when the branch B is selected by switches 38 and 39, also operated by the ganging bar 31.
  • the increase of selectivity associated with the decrease in the frequency of the transmission range may be so great that no other frequency-selective means are necessary in order to secure the selectivity required in broadcast reception.
  • the couplings provide two paths in parallel, one, I9, transmitting only a range of 0.009 mc. near 0.5 mc., and the other, 20, transmitting only a band near 6.5 mc. vThe former will not transmit anything when channel A is open, the latter will not transmit anything when channel B is open.
  • Figs. 4 and 5 are the preferred embodiments of the invention.
  • the frequency changer I2 For in order to add broadcast reception to television reception al1 that has to be added is the frequency changer I2 with its local oscillator I3 and the condensers I6, I1 or the parallel paths.
  • the frequency-changer I2 produces the conventional I. F. and can be of a conventional type; and the frequency-changer, when it is no longer required, can be used as an amplifier.
  • the frequency changer is a hexode
  • the signal input will usually be applied to the rst control grid and the local oscillations to the second control grid; when it is to be used as an amplifier the second control grid will be held at a fixed potential or used for gain control.
  • a heterodyne radio receiver adapted to receive alternately broadcast sound signals and sound accompanied television signals, comprising means for receiving the television and accompanying sound signals, said means comprising a first frequency-changer common to both the vision and sound channels, means for receiving the broadcast sound signals,said means comprising a second frequency-changer adapted to produce the broadcast sound intermediate frequency, means connecting the input of said second frequency changer to a broadcast sound receiving aerial and means connecting the output of said second frequency-changer to the input of said first frequency-changer, means for rendering operative either the said television and accompanying sound receiving means or the said broadcast sound receiving means, and means for converting said first frequency-changer into an amplifier when the said broadcast sound receiving means is rendered operative.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Multimedia (AREA)
  • Superheterodyne Receivers (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
US285832A 1938-07-27 1939-07-22 Radio-receiving apparatus Expired - Lifetime US2270652A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB22391/38A GB516901A (en) 1938-07-27 1938-07-27 Improvements in radio-receiving apparatus

Publications (1)

Publication Number Publication Date
US2270652A true US2270652A (en) 1942-01-20

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Family Applications (1)

Application Number Title Priority Date Filing Date
US285832A Expired - Lifetime US2270652A (en) 1938-07-27 1939-07-22 Radio-receiving apparatus

Country Status (4)

Country Link
US (1) US2270652A (enrdf_load_stackoverflow)
FR (2) FR858159A (enrdf_load_stackoverflow)
GB (1) GB516901A (enrdf_load_stackoverflow)
NL (1) NL60307C (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2491808A (en) * 1942-08-06 1949-12-20 Gen Electric Multichannel radio and television receiver
US2516009A (en) * 1948-10-28 1950-07-18 Westinghouse Electric Corp Converter system
US2609441A (en) * 1949-12-01 1952-09-02 Rca Corp Combination radio television receiving system
US2611818A (en) * 1949-12-01 1952-09-23 Rca Corp Combination radio and television receiving system
US2617878A (en) * 1949-04-21 1952-11-11 Motorola Inc Combination radio and television chassis
US2684402A (en) * 1949-12-31 1954-07-20 Stromberg Carlson Co Dual-purpose carrier-wave receiver
US2686221A (en) * 1949-11-03 1954-08-10 Rca Corp Simplified compbination fm and television receiver
DE1072651B (enrdf_load_stackoverflow) * 1951-04-05 1960-01-07

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE955605C (de) * 1952-07-12 1957-01-03 Blaupunkt Werke G M B H Zweign Kombiniertes Fernseh- und Rundfunkgeraet
GB2173660B (en) * 1985-03-28 1989-01-25 Multitone Electronics Plc Paging receivers

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2491808A (en) * 1942-08-06 1949-12-20 Gen Electric Multichannel radio and television receiver
US2516009A (en) * 1948-10-28 1950-07-18 Westinghouse Electric Corp Converter system
US2617878A (en) * 1949-04-21 1952-11-11 Motorola Inc Combination radio and television chassis
US2686221A (en) * 1949-11-03 1954-08-10 Rca Corp Simplified compbination fm and television receiver
US2609441A (en) * 1949-12-01 1952-09-02 Rca Corp Combination radio television receiving system
US2611818A (en) * 1949-12-01 1952-09-23 Rca Corp Combination radio and television receiving system
US2684402A (en) * 1949-12-31 1954-07-20 Stromberg Carlson Co Dual-purpose carrier-wave receiver
DE1072651B (enrdf_load_stackoverflow) * 1951-04-05 1960-01-07

Also Published As

Publication number Publication date
NL60307C (enrdf_load_stackoverflow)
FR858328A (fr) 1940-11-22
GB516901A (en) 1940-01-15
FR858159A (fr) 1940-11-19

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