US2201325A - Radio receiver circuit arrangement - Google Patents

Radio receiver circuit arrangement Download PDF

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Publication number
US2201325A
US2201325A US245831A US24583138A US2201325A US 2201325 A US2201325 A US 2201325A US 245831 A US245831 A US 245831A US 24583138 A US24583138 A US 24583138A US 2201325 A US2201325 A US 2201325A
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United States
Prior art keywords
circuit
circuits
band
frequency
frequencies
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Expired - Lifetime
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US245831A
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English (en)
Inventor
Tellegen Bernardus Do Hubertus
Adelbert Van Weel
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RCA Corp
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RCA Corp
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Filing date
Publication date
Application filed by RCA Corp filed Critical RCA Corp
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Publication of US2201325A publication Critical patent/US2201325A/en
Anticipated expiration legal-status Critical
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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
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
    • H04B1/14—Automatic detuning arrangements
    • 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
    • H04B1/302—Circuits for homodyne or synchrodyne receivers for single sideband receivers

Definitions

  • the invention relates, to a radio receiver cir- I cuit'arrangement, in which means are applied to suppress interferences occurring within one of wave in respect to at least the frequencies of the non-suppressed side-band which correspond to the modulation frequencies giving rise to the greatest modulation-depths.
  • the circuit arrangement may comprise, for example, an electric filter with a resonance curve which shows a comparatively sharp peak at the frequency corresponding to the carrier-wave of the received signal, which has a steep flank on one side of said peak and which extends on the other side al mcst horizontally over at least that part of the side-band to be transmitted which corresponds to the modulation frequencies giving rise to the greatest modulation depths.
  • the electric filter is preferably constituted by a number .of oscilvlatory circuits with different damping, the circuit with the lowest damping being coupled to one or more of the other circuits in such manner that thefrequency, at which said peak occurs in the resonance curve of the electric filter, is equal to the natural frequency of the circuit with the lowest damping.
  • the circuit with the lowest damping is reierably used as the last circuit, a tuning indicator being connected to this circuit and the voltage for the automatic volume control being derived from the circuit preceding the last.
  • Fig. 1 shows a resonance curve of the filter to 1 be used, and the curves from which said rest)- nance curve is obtained by multiplication.
  • Fig. 2 is a form of construction of the circuit arrangement according to the invention.
  • Fig. 3 shows another embodiment of the cirt'; cuit arrangement.
  • Fig. 1 the dotted curve I represents an approximation of the desired resonance curve.
  • the frequency is stated in kilocycles oil resonance (detuning) in respect to the carrier-Wave, the 1 place of which is denoted by O.
  • the resonance curve extends substantially horizontally, but shows a strong peak at the frequency which corresponds to the carrier-wave of-the received signaLthus causing said freqnuency to be trans,-
  • the dotted resonance curve represented in Fig. 1 may be obtained by making use of four tuned oscillatory circuits.
  • the circuit arband-pass filter thus formed has a resonance curve which may be supposed to be produced from the multiplication .of two resonance curves situated with their peaks on both sides of the original natural frequency.
  • the frequencies, at which the peaks of said resonance curves are situated, may be called the coupling frequencies of the band-pass filter.
  • references 3 and 4 represent the above-mentioned imaginary resonance curves of one of the band-pass filters represented in Fig. 2.
  • the resonance curve of the formed band-pass filter may be supposed to be produced by multiplication of two resonance curves situated with their peaks on both sides of the frequency band surrounded by the two natural frequencies.
  • the curves 2 and 5 are the imaginary resonance curves of the other band-pass filter in Fig. 2.
  • the dotted resonance curve I is produced if the four imaginary resonance curves 2, 3, 4 and 5 are multiplied by one another.
  • the multiplication has the effect that the peak in the curve I does not coincide with the peak of the curve 2, but falls somewhat inwardly.
  • the voltage across the circuit preceding the last is maintained constant by means of the auto matic volume control, the voltage across the last circuit with the lowest damping varies as afunction of the frequency according to the resonance curve of said circuit, so that an accurate tuning of the receiver is possible by means of a tuning indicator connected to said last circuit.
  • the reference 6 represents the first mixing tube, the first control grid of which has the local oscillator voltage and the fourth control grid of which has the high-frequency or signal voltage fed to it.
  • the oscillator frequency is determined by the oscillatory circuit I, the tuning condenser of which is coupled mechanically to the tuning condensers of the high-freqency circuit 8 which is fed by the antenna 9.
  • the anode circuit of the mixing tube 6 comprises the circuit II of a band-pass filter I3 constituted by the circuits II and I2.
  • the circuit I2 is inserted in the grid circuit of an amplifier tube I3.
  • the anode circuit of said amplifiertube comprises a circuit I4 coupled capacitatively to the circuit I6 through an adjustable condenser I5.
  • a series-connection of a diode I'I-3Il and a parallel-connection of a condenser I8 and a resistance I9 are connected in parallel with a part of the circuit I6.
  • the low-frequency signal voltage is derived from said resistance by means of a sliding contact 20 and is conducted to a low-frequency amplifier not shown in the drawing through a conductor 2!.
  • a control voltage for the automatic volume control is taken from the end of the resistance 3I not connected to earth through a filter constituted by a resistance 32 and a condenser 33 and is conducted to the control grids of the tubes tobe controlled through a conductor 34.
  • the high-frequency voltage supplied by the antenna 9 is converted by the mixing tube 6 into an intermediate frequency voltage which is conducted to a second mixing tube 27 through a band-pass filter 26.
  • This second mixing tube converts the first intermediate frequency voltage into a voltage of lower intermediate frequency.
  • the anode circuit of the mixing tube 21 comprises the circuit I I of the band-pass filter which is com stituted by the circuits II and I2 and istuned to said low intermediate frequency. After being amplified by the amplifying tube I3, the voltage is conducted to the capacitatively coupled circuits I4 and I6.
  • This part of the circuit arrangement corresponds in principle entirely to the part of the circuit-arrangement in Fig. 2 following the mixing tube 6 so that it need not again be described in detail.
  • the reason of the second intermediate frequency transformation is that it is very difiicult to manufacture an oscillatory circuit of sufficiently low damping at an intermediate frequency I of 450 kilocycles. It is therefore necessary to change over to a lower intermediate frequency, say kilocycles or 60 kilocycles, which is possible by means of a second mixing tube. Said circuit arrangement is therefore only useful for receivers in which a high intermediate frequency is applied, unless one wishes to make use of an additional advantage involved by the use of a second mixing tube. In fact the conversion of the oscillator frequency by the second mixing tube makes it possible to suppress one side-band or the other without any additional changing-over of oscillatory circuits, so that the switch may be simpler and thecircuits may be constructed with a lower damping.
  • a receiving circuit means for suppressing one of the side-bands of the received signal and accentuating the carrier-wave in respect to the frequencies of the non-suppressed side-band, said means comprising an electric filter which is constituted by four oscillatory circuits which form part of the receiving cascade, two of said circuits forming a band-passfilter with approximately critical coupling and which are tuned to a frequency approximately in the middle of the transmitted side-band, the two other circuits being loosely coupled to each other and having a damping which is lower than the damping of the former circuits and being tuned successively to frequencies on both sides of the coupling frequencies of theiband-pass filter, the tuning frequency of the circuit with the lowest damping corresponding to the carrier-wave frequency of the received signal.
  • a receiving circuit means for suppressing one of the side-bands of the received signal and accentuating the carrier-wave in respect to the frequencies of the non-suppressed side-band, said means comprising a first pair of oscillatory circuits forming a band-pass filter with approximately critical coupling and which are tuned to a frequency approximately in the middle of the transmitted side-band, and a second pair of oscillatory circuits loosely coupled to each other and having a damping which is lower than the dampingof the first pair of circuits and being tuned sucessively to frequencies on both sides of the coupling frequencies of the band-pass filter, the tuning frequency of the circuit with the lowest damping corresponding to the carrier-wave frequency of the received signal.
  • a receiving circuit means for suppressing one of the side-bands of the received signal and accentuating the carrier-wave in respect to the frequencies of the non-suppressed side band, said means comprising an electron discharge device, a first pair of oscillatory circuits connected to the input of said discharge device and forming a band-pass filter with approximately critical coupling, said circuits being tuned to a frequency approximately in the middle of the transmitted side-band, a second pair of oscillatory circuits connected to the output of said discharge device,
  • circuits being loosely coupled to each other damping corresponding to the carrier wave frev quency of the received signal, a signal detector coupled to said last-mentioned circuit, and an automatic volume control rectifier connected to the other of said low damped circuit.
  • intermediate frequency amplifier tube a pair of means for simultaneously detuning each of the above coupled circuits except the one tuned to the carrier-wave so that the overall transmission characteristic of said circuits is such that one of the side-bands of the received signal is suppressed and the carrier-wave is accentuated to substantially twice the value of the transmitted side-band-frequencies.
  • an intermediate frequency amplifier tube In a circuit of the superheterodyne type, an intermediate frequency amplifier tube, a pair of critically-coupled circuits normally tuned to the operating intermediate frequency and connected to the input of said tube, a pair of loosely-coupled circuits of low damping connected to the output of said tube, the first of said loosely-coupled circuits being normally tuned to the operating intermediate frequency and the second of said circuits being tuned to the carrier-wave, and means for simultaneously detuning each of the above coupled circuits except the one tuned to the carrier-wave so that the overall transmission characteristic of said circuits is of a form having a sharp peak at the frequency corresponding to the carrier-wave of the received signal with a sharp cut-off on one side of the peak, the other side of the peak extending substantially horizontally over the width of one of the side-bands to be transmitted.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Circuits Of Receivers In General (AREA)
US245831A 1938-06-04 1938-12-15 Radio receiver circuit arrangement Expired - Lifetime US2201325A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL2201325X 1938-06-04

Publications (1)

Publication Number Publication Date
US2201325A true US2201325A (en) 1940-05-21

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ID=19873858

Family Applications (1)

Application Number Title Priority Date Filing Date
US245831A Expired - Lifetime US2201325A (en) 1938-06-04 1938-12-15 Radio receiver circuit arrangement

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US (1) US2201325A (en:Method)
FR (1) FR855735A (en:Method)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2551228A (en) * 1946-05-31 1951-05-01 Rca Corp Tuning means for resonant transmission lines
US2699497A (en) * 1950-06-22 1955-01-11 Du Mont Allen B Lab Inc Television receiver

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2551228A (en) * 1946-05-31 1951-05-01 Rca Corp Tuning means for resonant transmission lines
US2699497A (en) * 1950-06-22 1955-01-11 Du Mont Allen B Lab Inc Television receiver

Also Published As

Publication number Publication date
FR855735A (en:Method) 1940-05-18

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