US2171154A - Radio receiver - Google Patents

Radio receiver Download PDF

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Publication number
US2171154A
US2171154A US21346A US2134635A US2171154A US 2171154 A US2171154 A US 2171154A US 21346 A US21346 A US 21346A US 2134635 A US2134635 A US 2134635A US 2171154 A US2171154 A US 2171154A
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US
United States
Prior art keywords
circuit
energy
homodyne
frequency
oscillator
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
US21346A
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English (en)
Inventor
Wright George Maurice
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.)
RCA Corp
Original Assignee
RCA Corp
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 RCA Corp filed Critical RCA Corp
Application granted granted Critical
Publication of US2171154A publication Critical patent/US2171154A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • H04B1/30—Circuits for homodyne or synchrodyne receivers

Definitions

  • This invention relates to radio receivers and more specifically to radio receivers of the socalled homodyne kind, i. e., of the kind in which received modulated carrier wave energy is mixed s with unmodulated carrier energy which should (for proper operation) be of the same frequency as the carrier frequency component in the received energy.
  • a typical known homodyne receiver comprises an aerial tuned to a desired frequency and coupled to a closed oscillatory circuit which is also tuned to the same frequency, there being introduced into this circuit a strong unmodulated carrier frequency derived from a local homodyne oscillator of the same frequency as the carrier component of the received energy and in predetermined phase relationship thereto.
  • the combined carrier energy i.
  • Known rectiflers are not rectilinear as to their voltage (ordinates) current (abscissae) characteristics and in general the characteristic of a rectifier has a markedly curved part commencing at the origin, the curved part continuing into a substantially straight portion.
  • the object of the present invention is to reduce this effect and the said invention consists in principle in so arranging the homodyne oscillator portion of a homodyne receiver that the time per cycle of homodyne oscillator during which the rectifier can produce audio frequency components by rectification of unwanted carriers is substantially reduced.
  • the invention may be carried into effect in any of three principal ways, (1) by utilizing in place of a homodyne oscillator giving a more or less sinusoidal output an arrangement giving synchronized pulses; (2) by the use of a homodyne oscillator giving a substantially square topped output wave; and (3) by the use of a homodyne oscillator in such manner that only the tips or peaks of the locally generated wave are utilized.
  • a homodyne receiver compris-es an aerial I which maybe tuned to the desired frequency and is coupled by means of a coil 2 to a parallel tuned circuit 3 tuned to the incoming radio frequency.
  • One end of this tuned circuit is connected to the control grid 4 of a triode 5 which is adjusted to operate as a rectifier, the other end of the tuned circuit being connected through a resistance 6 toI the cathode 'I of the triode.
  • Device Il represents schematically an ordinary local oscillator having an output circuit connected to the input terminals of a limiter stage or device l2.
  • the output terminals of the limiter are connected across a resistance 6.
  • the Wave form applied across the ends of the resistance 6 Will be of substantially square-topped form and accordingly the period of time per cycle during which the rectifier is operated upon the curved portion of its characteristic isv substantially re-l cuted by reason of the square-topped formation of the local oscillation wave actually applied.
  • the limiter I2 may take the form of that described in Shore U. S. Patent No. 2,005,111.
  • a signal input circuit including means for tuning the circuit to the frequency of desired signal energy, a heterodyne frequency generator, a combining circuit including a rectifier tube and means for feeding the desired signal energy to the combining circuit, means for feeding the heterodyne energy to the combining circuit, said last named means including a limiter device interposed between the heterodyne frequency generator and the combining circuit, said limiter device being arranged so as to distort the wave form of the energy produced by the heterodyne frequency generator so that the energy impressed upon the combining circuit through the limiter device has a non-sinusoidal wave form.
  • a combining circuit including a detector tube provided with a tunable signal input circuit and an output circuit, a signal energy pick-up device coupled to said input circuit, a local oscillator, means for coupling the local oscillator to said input circuit, said last named means including a device for attening the Wave form of the energy produced by the local oscillator to such an extent as to cause the detector output current to be substantially Zero during at least half of each cycle of the local oscillator energy and large and relatively uniform during the remainder of the cycle.
  • a combining circuit including a detector tube having a tunable signal input circuit and an output circuit, a signal energy pick-up device coupled to the input circuit, an oscillation generator, means for feeding the generated oscillations into the combining circuit, said means including a limiter device adapted to change the generated oscillations to substantially square topped waves.
  • a method of radio reception which includes the steps of receiving signal modulated carrier energy of the desired frequency, producing substantially square topped oscillations of the same frequency and phase as the received energy, modulating the received energy by the produced oscillations and deriving the signals from the products of said modulation,
  • a signal wave pick-up means In radio receiving apparatus, a signal wave pick-up means, a utilizing circuit, a variable resistance coupling circuit for transferring signal Waves from the pick-up means to the utilizing circuit, and means electrically connected to said coupling circuit and including a device for generating substantially square topped waves for alternately and periodically varying the resistance of the coupling circuit substantially instantaneously from one value tol another at the same frequency and phase as the desired signalling energy whereby the coupling circuit presents a substantially constant resistance to one half of each signal wave cycle and a substantially constant but different resistance to the other half of each signal wave cycle.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Superheterodyne Receivers (AREA)
  • Noise Elimination (AREA)
  • Burglar Alarm Systems (AREA)
  • Circuits Of Receivers In General (AREA)
US21346A 1934-06-02 1935-05-14 Radio receiver Expired - Lifetime US2171154A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB16505/34A GB439206A (en) 1934-06-02 1934-06-02 Improvements in or relating to radio receivers

Publications (1)

Publication Number Publication Date
US2171154A true US2171154A (en) 1939-08-29

Family

ID=10078548

Family Applications (1)

Application Number Title Priority Date Filing Date
US21346A Expired - Lifetime US2171154A (en) 1934-06-02 1935-05-14 Radio receiver

Country Status (6)

Country Link
US (1) US2171154A (enMihai)
BE (1) BE409533A (enMihai)
DE (1) DE673784C (enMihai)
FR (1) FR790630A (enMihai)
GB (1) GB439206A (enMihai)
NL (1) NL43295C (enMihai)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2471418A (en) * 1941-01-17 1949-05-31 Int Standard Electric Corp Interference reducing radio impulse receiver
US2773979A (en) * 1953-02-02 1956-12-11 Philco Corp Frequency converter
US2813973A (en) * 1953-01-30 1957-11-19 Philco Corp Diode frequency converter with nonsinusoidal local oscillation source

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2471418A (en) * 1941-01-17 1949-05-31 Int Standard Electric Corp Interference reducing radio impulse receiver
US2813973A (en) * 1953-01-30 1957-11-19 Philco Corp Diode frequency converter with nonsinusoidal local oscillation source
US2773979A (en) * 1953-02-02 1956-12-11 Philco Corp Frequency converter

Also Published As

Publication number Publication date
DE673784C (de) 1939-03-29
NL43295C (enMihai)
FR790630A (fr) 1935-11-25
GB439206A (en) 1935-12-02
BE409533A (enMihai)

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