US2676248A - Superregenerative receiver - Google Patents

Superregenerative receiver Download PDF

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Publication number
US2676248A
US2676248A US239262A US23926251A US2676248A US 2676248 A US2676248 A US 2676248A US 239262 A US239262 A US 239262A US 23926251 A US23926251 A US 23926251A US 2676248 A US2676248 A US 2676248A
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Prior art keywords
circuit
anode
oscillation
damping
tube
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Expired - Lifetime
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US239262A
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English (en)
Inventor
Schmidt Johan Machiel
Johannes Jacobus Zaalber Zelst
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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
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D11/00—Super-regenerative demodulator circuits
    • H03D11/02—Super-regenerative demodulator circuits for amplitude-modulated oscillations

Definitions

  • receivers-1 are! known to havea discharge; tuberoperatingaas. ani'oscillatcr; whose frequency is; determined by; the input. signal circuit. andwh se damning svvariedfby'a sor-(ial'led.
  • thetube may comprise acathode, an anode and a control-grid; ;a.circuittuned to the incoming frequency, and responsive to an incoming; signal is connected between the; cathode and the: controlsgrid, the anode; circuit being coupled withthe grid circuitin-atmannersuchthat positive, feed-back occurs, so that: a, negative damping effect isiproduced across the circuit-J and the; am-
  • the-amplitude of theoscillation is to increase by" approximately a factor 10 and decrease again in a single cycle of the quenching oscillation, which is composed of a negative damping period'and a positive damping period.
  • The-quenching period is to be solong that at the-end of the positivedamping period theoscillations may: have dropped below the noist level.
  • The-required amountof positive I or negative circuit' damping-must ibesumcient to increase or 3 Claims; (Cl.
  • the frequency of the quench ing oscillation must-be high relative to the highest modulation frequency of the oscillationsto be received. It may be inferred therefrom that the band width of the circuit" is to be approximately ten times the-maximum modulation frequency;
  • The-object of: the; invention is to provide aareceivergof thevkind doscribedin the preamble, in which the said; switching-om phenomenon is re.- prisedrtoa have; a negligible. effect. Therefore, this-newreceiver will beadapted totherecept-ion of osciilations :of longerwavelength; for example, ofimorethan1001mmv Since, for-the same reason, it'is possible to: choose aconsiderablyhigher quenching frequency in the inventors circuitarrangement than in the known circuit-arrangemerits; the new receiver is at the same time suitable for the reception of high frequency oscillations, which are modulated in WVBIYf-Wldfi ire.- quency-rangeysuclras used-in television;
  • a superregenerative receiver it is furthermore known to connect two. tubes in the input oscillation circuit in push-pull so that the anode circuits act in parallel on the load. In'this case. however, one tube exclusively serves for producing damping for the other. Since the quenching oscillation is supplied in phase opposition to the tubes, the total direct current component of the anode current may be regulated to vary only slightly. However, in this manner it is not pos sible to eliminate the aforesaid switching-on phenomenon as this would require an adjustment of the currents so accurate as to be unobtainable in practice. 1
  • FIGS. 3, 4 and 5 show alternative embodiments of the invention and in which Figs. 3, 4 and 5 are graphs which aid in the explanation of the invention.
  • Fig. 1 shows a circuit-arrangement comprising a single tube operating as a superregenerative detector, shown here as a triode'for the sake of simplicity.
  • This circuit is grounded at one end and connected at the other end through ,a capacitor 4 to the control-grid of a tube 5.
  • the anode of the latter is connected through a feedback coil 1 coupled with the inductance 2 and through a resistor 8 to the positive terminal of thecurrent supply.
  • the modulation oscillations are taken from terminals 9.
  • the grid of the tube is grounded through a leak resistor 6.
  • the feedback is such that it produces across the circuit l spontaneous oscillations which are periodically quenched in accordance with the superregenerative principle. According to the invention, this is effected in the circuit-arrange ment shown by connecting in parallel with the circuit the series combination of a resistor I I and a rectifier l2. To the terminals ll) of the resistor II is connected at quenching frequency generator The characteristic curve of the latter is approximately a rectangular wave.
  • the leading edges of the voltage Waves are slightly rounded off; the horizontal line of Fig. 3 indicates the zero line at which no bias voltage is operative across the rectifier l2.
  • the rectifier 12 operates as avirtual rectifier, which only rec- .tifies the positive halves of each cycle of the highfrequency voltage operative across circuit 2, 3. At the time of such rectification the circuit is damped to such an extent that the oscillations produced across it by the oscillator tube rapidly decrease in amplitude to a'very low value. If during the occurrence of a positive voltage pulse the upper terminal I0 becomes positive, the rectifying action abruptly ceases, which, however, is not attended. by a variation of the direct current component across the circuit.
  • the wave form'of the quenching interruption oscillation need not be rectangular; as an alternative; this voltage may be composed of a sine voltage superposed on a direct voltage, which is approximately equal to the maximum value of the sine voltage, as is shown in Fig. 4. As a further alternative, use may be made of a saw-tooth voltage preferably having a steep trailing edge (Fig. 5). However, inall cases the voltage should be such that the rectifier cannot carry an appreciable direct current component.
  • the rectifier I2 should preferably have a sharply bentover characteristic curve, so that it will have a low internal resistance at a low amplitude of the high-frequency oscillations in, the circuit.
  • the maximum value of the resistor, H is set by the requirement that the parallel com bination l I, I2 should exert a strong damping influence on the circuit 2, 3. This requirement also. determines the-resistance of the rectifier i2 in rectifying condition.
  • the rectifier l2 has excessive capacitance when a positive voltage pulse is produced at the upper terminal of the resistor H, the resultant charge current may cause a switching-on phenomenon which poduces interfering oscillations. Consequently, this capacitance should be low, for example lower than 1 micro-microfarad. It has been found that for the purpose of the invention.
  • Germanium rectifiers are very suitable, since they have not only a low capacitance but can also resist comparatively high voltages, for example, 50 v. and upwards. This is or importance since the cut-01f voltage of the rectifier is to be higher than the maximum amplitude of the high-frequency oscillation in the circuit.
  • the latter voltage may, for example, be of the order of v.
  • Fig. 2 shows a circuit-arrangement, in which use is made of a push-pull combination of two discharge tubes l5 and It.
  • the oscillation circuit is connected between the anodes of the tubes; the circuit inductance It is provided with a central tap.
  • the anode circuit furthermore comprises the resistor 8, from the lower end of which the modulation voltage is taken at the terminals 0.
  • rectifiers 2i and 22 are connected, in opposite sense, in parallel with the circuit 3, is.
  • the junction of these rectifiers is connected through a resistor H to the central tap on the coil M.
  • Ihe quenching oscillation is supplied through terminals to resistor M. This quenching oscillation has such a Wave form that a direct current component cannot pass through the rectifier.
  • the rectifiers may be replaced by other elements, for example, controlled discharge tubes, by means of which the circuit is short-circuited or strongly damped during the damping period.
  • the short-circuit may even be carried out with the use of a mechanical switch. This may be of importance for measuring purposes, if the frequencies are very low. However, care should be taken that no strong direct-current variations occur at the beginning of the negative damping period.
  • a superregenerative receiver wherein an incoming signal is regenerated and periodically quenched by a quenching oscillation
  • the combination comprising a pair of electron discharge tubes each having a cathode, a control grid and an anode, a push-pull resonant circuit tuned to said incoming signal and including a centertapped inductor connected between the anodes of said tubes, means to cross-couple the grids and anodes of said tubes to effect regeneration, means to apply an operating potential for said tubes between the cathodes thereof and the center-tap of said inductor, a pair of unidirectionally conductive devices, a damping resistance for said resonant circuit having one end connected to said center-tap and having the other end connected in one direction through one of said devices to the anode of one tube and connected in the other direction through the other of said devices to the anode of the other tube, and means to apply the quenching oscillation across said damping resistance.
  • the device comprising a pair of electron discharge tubes each having a cathode, a control grid and an anode, a push-qoull resonant circuit tuned to said incoming signal and including a center-tapped inductor connected between the anodes of said tubes, means to cross-couple the grids and anodes of said tubes to effect regeneration, means to apply an operating potential for said tubes between the cathodes thereof and the center-tap of said inductor, a pair of rectifiers, a damping resistance for said resonant circuit having one end connected to said center-tap and having the other end connected in one sense through one of said rectifiers to the anode of one tube and connected in the other sense through the other or said rectifiers to the anode of the other tube, and means to apply the quenching oscillation across said damping resistance.
  • the device comprising a pair of electron discharge tubes each having a cathode, a control grid and an anode, a push-pull resonant circuit tuned to'said incoming signal and including a center-tapped inductor connected between the anodes of said tubes and a variable condenser connected across said inductor, capacitive means to cross-couple the grids and anodes of said tubes to eflect regeneration, means to apply an operating potential for said tubes between the cathodes thereof and the center-tap of said inductor, a pair of germanium diodes, a damping resistance for said resonant circuit having one end connected to said center-tap and having the other end connected in one sense through one of said diodes to the anode of one tube and connected in the other sense through the other or said diodes to the anode of the other tube, means to apply the quenching oscillation

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)
US239262A 1950-08-23 1951-07-30 Superregenerative receiver Expired - Lifetime US2676248A (en)

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NL2676248X 1950-08-23

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US (1) US2676248A (fr)
BE (1) BE505370A (fr)
FR (1) FR1048021A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3005910A (en) * 1955-03-01 1961-10-24 Richard R Florac Radio-frequency circuit

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2044061A (en) * 1935-05-24 1936-06-16 Bell Telephone Labor Inc Radio repeating system for ultra-short waves
US2412710A (en) * 1944-07-15 1946-12-17 Philco Corp Superregenerative receiver quenching circuit
US2553219A (en) * 1946-04-02 1951-05-15 Philco Corp Superregenerator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2044061A (en) * 1935-05-24 1936-06-16 Bell Telephone Labor Inc Radio repeating system for ultra-short waves
US2412710A (en) * 1944-07-15 1946-12-17 Philco Corp Superregenerative receiver quenching circuit
US2553219A (en) * 1946-04-02 1951-05-15 Philco Corp Superregenerator

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3005910A (en) * 1955-03-01 1961-10-24 Richard R Florac Radio-frequency circuit

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Publication number Publication date
FR1048021A (fr) 1953-12-18
BE505370A (fr)

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