US2161320A - Modulation system for radio transmitters - Google Patents

Modulation system for radio transmitters Download PDF

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Publication number
US2161320A
US2161320A US135721A US13572137A US2161320A US 2161320 A US2161320 A US 2161320A US 135721 A US135721 A US 135721A US 13572137 A US13572137 A US 13572137A US 2161320 A US2161320 A US 2161320A
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United States
Prior art keywords
amplifier
carrier
circuit
impedance
stage
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
US135721A
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English (en)
Inventor
Schulze-Herringen Erich
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.)
Alcatel Lucent Deutschland AG
C Lorenz AG
Original Assignee
Standard Elektrik Lorenz AG
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 Standard Elektrik Lorenz AG filed Critical Standard Elektrik Lorenz AG
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Publication of US2161320A publication Critical patent/US2161320A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/04—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in discharge-tube amplifiers
    • H03F1/06—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in discharge-tube amplifiers to raise the efficiency of amplifying modulated radio frequency waves; to raise the efficiency of amplifiers acting also as modulators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C1/00—Amplitude modulation
    • H03C1/52—Modulators in which carrier or one sideband is wholly or partially suppressed
    • H03C1/60—Modulators in which carrier or one sideband is wholly or partially suppressed with one sideband wholly or partially suppressed

Definitions

  • Fig. 1 is a diagrammatic View of a known transmitters methods varaknownin which a saving of mitting system having separate carrierand side energy is effected by separating carrierfrequency band amplifiers.
  • Fig. 2 is a View similar to Fig.
  • Fig. 3 is a graphic representation that ⁇ 5 methods have thefdisadvantage that lthe carrier serves to explain this idea.
  • Fig. 4 is a wiring amplifier may-operateat a highl efficiency, only diagram of a device that forms part of the arthe side band amplifier having to operate at a rangements shown in Figs. 1 and 2 and acts to low efficiency. In arrangements of thisk kind, separate the side bands from the carrier.
  • Fig. 6 is a graphic that occur in the antenna the highly efficient representation that relates to the function of an carrier amplier ⁇ will, deliver yless power if the amplifier adapted for use in connection with l5 modulation degree Vis increasing. VIf such dethe arrangement shown in Fig. 2.
  • Fig. '7 is a 15 crease in power loutput were to be avoided then graphic representation which serves to explain the ycarrier amplifier rwould have to operate at distortions which occur in amplifiers of this kind.
  • Fig. 8 is a graphic representation that relates to saving of energy would get lost. Therefore, as the function of amplifiers used in arrangements stated before, the two amplifiers have been caused as provided by the invention.
  • Fig. 9 is a wiring 20 to act on separate antennae which are as far as diagram of these arrangements. possible neutralized with regardto each other, Reverting to Fig. 1, in which a known arso that there shall be no coupling effect between rangement is shown, S denotes the control stage, them. To such end the antennae are spaced I the stagein which the side bands are separated apart by a sufliciently large distance, or addirfrom' the carrier, the carrier being suppressed 25 tional means are kprovided for establishing an here.
  • the invention proposes to cause carrier amlthe reference characters are as far as possible 35 Dlier and Side bandamplier to act on a comthe same as used in Fig. 1.
  • the two nal ammon or single utilization circuit and also prof yplifiers El, E2 are here arranged to act on an Vides means adapted to avoid the s'a'id reaction, antenna common to them.
  • Vides means adapted to avoid the s'a'id reaction, antenna common to them.
  • a member CI is interposed that 0 plier has upon the carrier amplifier.
  • CI phase bridge or chain systeml
  • an energy line such for example as aconcentric high frequency cable, of such length that the phase rotation by or so called phase quadrature shall be obtained in this way.
  • Such cable may for instance be wound on a drum or may be'bent on its way to the antenna coupling cabin. rIlhe first arrangement has the advantage that only a single energy line leading from the transmitter to the antenna is necessary.
  • FigrS shows how the output delivery of the final stage E2 increases with decreasing output impedance.
  • the output efiiciency N is here plotted with respect to the output impedance Z.
  • the top of the curve is the limit between the high and low efficiency states.
  • the operation On the left-hand side of the dotted line y the operation is effected at low efli'ciency while on the right-hand side thereof it takes place at high efiiciency.
  • the carrier amplifier is to operate at a high efiiciency, the working point is located in the region of high efliciency, for instance at P. To this working point a certain output efciency N l corresponds, the output impedance being of the value ZI.
  • terminals 3, 4 the carrier is supplied.
  • Cl may ofA rtotal current.
  • the final stage of the side band amplifier may be constructed as an amplifier in Class B connection.
  • Fig. 6 discloses the conditions which relate to such a Class B amplifier.y
  • the working point P is located in the lowerbend of the idealized characteristic curve K.
  • the side bands Sv are conducted to the grid of the stage and are after amplification derived from the anode circuit in an undistorted condition. With arrangements of this kind the at-rest current initsunmodulated state is equal to zero.
  • the real characteristic curve of an amplifier tube has no sharp bend at its lower end, that is to say, does notl join the zero line in the manner represented inrFig.
  • a further feature of the invention proposes to insert a single-way rectifier into the grid circuit of the Class B amplifier, such for example as a diode that acts to cut away one half of the side bands.
  • the working characteristic of the rectifier shouldbefmade as straight as possible.
  • Fig. 8 shows the mode of action of such an arrangement.
  • the working point is point P, located at the end of the straight portion of the characteristic K.
  • Fig; 8 Only curve lines of the kind represented in Fig; 8 are conveyed to the grid circuit of the tube, the other curve lines, which are in the nature of mirror refiections to the former, being cut away.
  • Fig. 9 by Way of example shows a wiring diagram of the iinal stage of the Class B amplifier. 'I'he working'point P is adjusted by regulating the grid bias G. The diode D in the grid circuit acts to cut' awayr one half of the curves conveyed over transformer T. By tuning; the anode circuit of the stage the carrier Wave'may be filtered out so that the two side bands are reproduced in their original form.
  • the working point is displaced in the customary manner into the point where the characteristic curve of the Class B amplifier and the zero line intersect, and the working characteristic of the rectifier is so chosen that distortions which are due to the curvature of the amplifier characteristic shall be compensated by the curvature of the rectifier characteristic.
  • the novel arrangement thus ensures that when the carrier amplifier is operating at high efficiency an impedance increase that occurs in the utilization circuit does not decrease the power output but acts to increase it. In this way a saving in the expense for place requirements and installation is made as compared with prior arrangements of the kind operating likewise at high efficiency, since one of the usual antenna arrangements is now dispensed with.
  • a surplus expenditure resides only in the provision of an additional length of energy line, namely the M4 length necessary for effecting the described phase shift,this expenditure however being immaterial over the said advantage of the novel arrangement.
  • a radio transmitting system having means for obtaining and separating side bands from a carrier, an amplifier for the carrier frequency, a high eflciency amplifier for the side bands, and a single utilization circuit, means for coupling said amplifiers to said utilization circuit, and means for reversing in the output circuit of the carrier amplifier impedance-variations occurring in said utilization circuit.
  • the side band amplifier is of the Class B type having a vacuum tube with anode, cathode and grid circuit, comprising a one-way rectifier included in the grid circuit and means adapted for displacing the working point into the starting point of the straight part of the characteristic curve of the Class B amplifier.
  • the side band amplifier is of the Class B type having a vacuum tube with anode, cathode and grid circuit, comprising a one-way rectifier included in the grid circuit and having a straight characteristic curve.
  • the side band amplifier is of the Class B type having a vacuum tube with anode, cathode and grid circuit, comprising a one-way rectifier included in the grid circuit and means adapted for displacing the Working point into the point of intersection of the characteristic curve and zero line, the characteristic curve of this rectifier being such that distortions caused by the characteristic curve of the Class B amplifier are compensated.
  • An arrangement according to claim 1 means inserted between the utilization circuit and the output circuit of the carrier frequency amplifier for quadrature phase shifting the high frequency output of said amplifier, and a second means producing the same angular phase shift to compensate for the first mentioned phase shift.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
  • Transmitters (AREA)
US135721A 1936-04-09 1937-04-08 Modulation system for radio transmitters Expired - Lifetime US2161320A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE483883X 1936-04-09

Publications (1)

Publication Number Publication Date
US2161320A true US2161320A (en) 1939-06-06

Family

ID=6543039

Family Applications (1)

Application Number Title Priority Date Filing Date
US135721A Expired - Lifetime US2161320A (en) 1936-04-09 1937-04-08 Modulation system for radio transmitters

Country Status (4)

Country Link
US (1) US2161320A (enrdf_load_stackoverflow)
FR (1) FR820111A (enrdf_load_stackoverflow)
GB (1) GB483883A (enrdf_load_stackoverflow)
NL (1) NL48382C (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2543827A (en) * 1948-12-30 1951-03-06 Rca Corp Percentage modulation control network
US2604533A (en) * 1949-03-08 1952-07-22 Rca Corp Amplitude modulation
US4584692A (en) * 1982-12-07 1986-04-22 Fujitsu Limited Data transmitting-receiving system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2543827A (en) * 1948-12-30 1951-03-06 Rca Corp Percentage modulation control network
US2604533A (en) * 1949-03-08 1952-07-22 Rca Corp Amplitude modulation
US4584692A (en) * 1982-12-07 1986-04-22 Fujitsu Limited Data transmitting-receiving system

Also Published As

Publication number Publication date
GB483883A (en) 1938-04-27
FR820111A (fr) 1937-11-04
NL48382C (enrdf_load_stackoverflow)

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