US1725721A - Method and means for combining frequencies - Google Patents

Method and means for combining frequencies Download PDF

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Publication number
US1725721A
US1725721A US193411A US19341127A US1725721A US 1725721 A US1725721 A US 1725721A US 193411 A US193411 A US 193411A US 19341127 A US19341127 A US 19341127A US 1725721 A US1725721 A US 1725721A
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United States
Prior art keywords
circuit
bridge
reactance
coupling
energy
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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
US193411A
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English (en)
Inventor
Harold O Peterson
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
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RCA Corp
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Publication date
Application filed by RCA Corp filed Critical RCA Corp
Priority to US193411A priority Critical patent/US1725721A/en
Priority to GB15050/28A priority patent/GB291012A/en
Application granted granted Critical
Publication of US1725721A publication Critical patent/US1725721A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
    • H03D7/06—Transference of modulation from one carrier to another, e.g. frequency-changing by means of discharge tubes having more than two electrodes
    • H03D7/08—Transference of modulation from one carrier to another, e.g. frequency-changing by means of discharge tubes having more than two electrodes the signals to be mixed being applied between the same two electrodes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B15/00—Suppression or limitation of noise or interference
    • H04B15/02—Reducing interference from electric apparatus by means located at or near the interfering apparatus
    • H04B15/04—Reducing interference from electric apparatus by means located at or near the interfering apparatus the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder
    • H04B15/06—Reducing interference from electric apparatus by means located at or near the interfering apparatus the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder by local oscillators of receivers

Definitions

  • This invention relates to a method and means for combining frequencies, and more particularly for combining signal energy with energy from a local oscillator for heterodyning.
  • Figure 2 is a portion of Figure 1 rearranged in the form of a bridge.
  • the .signal circuit includes an antenna 2, a tuning condenser 4, a coupling coil 5, and a grounded connection 8. Within a double copper shield 10 there is mounted a local oscillator 12, the frequency 1927. Serial No. 193,411.
  • the wave combining unit, or rectifying unit consists of a triode or three electrode vacuum tube 16 having a cathode 18, a grid or control electrode 20, and a plate or anode 22.
  • the input circuit comprises a two part coupling reactance, exemplified in this case by the inductances 24 and 26, and a variable tuning condenser .28.
  • One side of this resonant input circuit is connected to the control electrode 20 while the other side is connected to the cathode 18 through the adjustable series condenser 30.
  • Energy from the local oscillator. is conveyed to the combining unit through an oscillator circuit 32, which is coupled to the oscillator at 34, as shown, and to the coupling reactance between the coils 24 and 26.
  • the oscillator circuit is completed by way of the grounded shielding through a grid biasing battery, 36, which makes the tube 16 operate at an asymmetric portion of its characteristic curve, to obtain rectification.
  • the coils 24 and 26 are equal, and the condenser 30 is equal to the natural overall grid to cathode capacitance, that is, the capacitance to filament, shielding, and ground.
  • the operation may be explained as follows: Signal energy applied to the input circuit 24, 26, 28, which is tuned to the signal frequency, causes signal current to flow thru the two parts of the coupling reactance 24 and 26 in series and the potential fluctuation between the terminal points A and B is applied to the control electrode 20. Oscillator energy from the circuit 32 flows thru the two parts of the coupling reactance in parallel, that is, it divides and flows equally and oppositely in the coils 24 and 26, in consequence of which it .is not transferred through the coil 6 to the antenna 2.
  • the terminals A and B fluctuate equally and simultaneously in potential, and if the terminal B were connected directly to the cathode 18 the oscillator energy would have no effect, for the grid and cathode would be at the same potential. But according to my invention thecondenser 30 is inserted between the point B and the cathode 18, and this is of very small magnitude and therefore of high reactance, and the potential fluctuations at B are overcomethrough this reactance before reaching the cathode 18.
  • the control electrode has impressed upon it both signal and local oscillations, and it being suit ably biased by the battery 36, the oscillations are combined, and their resultant beat is delivered to further circuits.
  • FIG. 2 shows a portion of the wiring in Figure l rearranged in the form of a bridge.
  • the bridge is composed of the input coupling coils 24,26, the condenser 30, and the natural overall grid to filament capacitance C.
  • Signal energy in the antenna circuit 2, 4:, 6, 8 is, in effect, applied to the bridge at the points A and B, while energy from the local oscillator 12 is applied through the circuit 32 to the other corners of the bridge.
  • both the signal and the oscillator energies cause potential differences to be applied thereto.
  • the bridge is most simply balanced when the coil 2& equals the coil 26, and the capacitance 0 equals that of the condenser 30, but it is clear that the coils 24, 26 need not be equal, for if unequal it is merely necessary to adjust the variable condenser 30 to bring the bridge to balance.
  • the condenser 30 should be made larger, thereby sending more current thru the coil 26 to obtain equal magnetic ef fects.
  • the arms 26 and 30 are equally decreased in reactance, as a result of which the terminal point B will remain at the same potential as the terminal point A with respect to the oscillator energy, which is the condition to be fulfilled to pre vent back coupling to the coil 6.
  • the method of the invention may therefore be described as applying signal energy across the terminals of an input reactance of a combining unit, applying local oscillator energy to the reactance at a point intermediate the terminals in potential, and causing the current flow from the local oscillator in both parts of the reactance to be of such relative magnitude that the potential fluctuations caused by the oscillator at the terminals of the reactance are equal and in phase.
  • the reactances 24 and 26 need not be inductances, for capacity coupling is equally feasible.
  • the combining unit or device of asymmetric characteristic employed need not necessarily be a vacuum tube, for other known means such as a saturable iron cored impedance may be used, and if a vacuum tube is used, it need not necessary be given its asymmetric characteristic by means of a biasing battery, although I think the arrangement shown is a preferable one.
  • the output frequency may be an intermediate frequency which must subsequently be detected to ob tain an audio frequency, or it may, if desired, be an audible frequency directly after heterodyning as in the case of telegraphy signals.
  • a combining tube having a cathode and a control electrode, a circuit including a two part coupling reactance and a series condenser connected be tween said electrodes, a signal circuit coupled to the two parts of the coupling reactance in series, and a local oscillator coupled to the two parts of the coupling reactance in parallel, the series condenser being of proper magnitude to cause the oscillator currents to so divide in the parts of the coupling reactance that they neutralize one another with respect to the signal circuit.
  • a combining tube having a grid and a grounded cathode, an input circuit comprising a coupling inductance and a tuning condenser connected in parallel therewith, means connecting one side of the input circuit to the grid, means including a series condenser whose capacitance equals the grid to ground-capacitance connecting the other side of the input circuit to the cathode, and a local oscillator circuit connected between the cathode and the midpoint of the coupling inductance.
  • An arrangement for combining energies of different frequencies obtained from differently tuned circuits while maintaining independence of tuning in said circuits comprising a combining tube having a grid and a cathode, a symmetrical bridge of reactances one arm of which is the natural overall grid to cathode impedance, a circuit for supplying energy of one frequency coupled across opposite corners of the bridge, a circuit for supplying energy of another frequency coupled across the other corners of the bridge, and an output circuit.
  • a heterodyne receiver In a heterodyne receiver, a three electrode vacuum tube having a grid and a grounded cathode, a reactance bridge, coupling coils comprising two adjacent arms of the bridge, a condenser and the natural grid to ground capacitance forming the other two arms of the bridge, a signalcircuit coupled across the bridge at the ends of the coupling coils, a local oscillator circuit connected between the coupling coils and across the other corners of the bridge, means to make the tube rectify, and an output circuit.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Geophysics And Detection Of Objects (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)
US193411A 1927-05-23 1927-05-23 Method and means for combining frequencies Expired - Lifetime US1725721A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US193411A US1725721A (en) 1927-05-23 1927-05-23 Method and means for combining frequencies
GB15050/28A GB291012A (enrdf_load_stackoverflow) 1927-05-23 1928-05-22

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US193411A US1725721A (en) 1927-05-23 1927-05-23 Method and means for combining frequencies

Publications (1)

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US1725721A true US1725721A (en) 1929-08-20

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US193411A Expired - Lifetime US1725721A (en) 1927-05-23 1927-05-23 Method and means for combining frequencies

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US (1) US1725721A (enrdf_load_stackoverflow)
GB (1) GB291012A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1013332B (de) * 1956-05-18 1957-08-08 Telefunken Gmbh Neutralisierungsschaltung fuer eine selbstschwingende Mischstufe, z.B. in Fernsehempfaengern mit Kanalschalter
DE967648C (de) * 1952-03-23 1957-12-05 Telefunken Gmbh Mischstufe mit additiver Mischung, insbesondere fuer den UKW-Empfang
DE968071C (de) * 1952-03-22 1958-01-16 Telefunken Gmbh Empfaenger mit wahlweiser Verstaerkung einer kurzwelligen Zwischenfrequenz beim UKW-Empfang oder einer kurzen Empfangswelle in derselben Empfaengerstufe

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE968071C (de) * 1952-03-22 1958-01-16 Telefunken Gmbh Empfaenger mit wahlweiser Verstaerkung einer kurzwelligen Zwischenfrequenz beim UKW-Empfang oder einer kurzen Empfangswelle in derselben Empfaengerstufe
DE967648C (de) * 1952-03-23 1957-12-05 Telefunken Gmbh Mischstufe mit additiver Mischung, insbesondere fuer den UKW-Empfang
DE1013332B (de) * 1956-05-18 1957-08-08 Telefunken Gmbh Neutralisierungsschaltung fuer eine selbstschwingende Mischstufe, z.B. in Fernsehempfaengern mit Kanalschalter

Also Published As

Publication number Publication date
GB291012A (enrdf_load_stackoverflow) 1928-09-20

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