US2212568A - Modulated high frequency transmitter system - Google Patents

Modulated high frequency transmitter system Download PDF

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Publication number
US2212568A
US2212568A US218466A US21846638A US2212568A US 2212568 A US2212568 A US 2212568A US 218466 A US218466 A US 218466A US 21846638 A US21846638 A US 21846638A US 2212568 A US2212568 A US 2212568A
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US
United States
Prior art keywords
grid
modulation
rectifier
stage
bias
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
US218466A
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English (en)
Inventor
Kramar Ernst
Heinecke 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
Priority to GB16595/35A priority Critical patent/GB445071A/en
Priority to FR794087D priority patent/FR794087A/fr
Priority claimed from US37122A external-priority patent/US2151921A/en
Application filed by Standard Elektrik Lorenz AG filed Critical Standard Elektrik Lorenz AG
Priority to US218466A priority patent/US2212568A/en
Application granted granted Critical
Publication of US2212568A publication Critical patent/US2212568A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C1/00—Amplitude modulation
    • H03C1/02—Details
    • H03C1/06—Modifications of modulator to reduce distortion, e.g. by feedback, and clearly applicable to more than one type of modulator

Definitions

  • the application of the slip-way method which as is well known works with anintensity indication, the descent being along a curve of constant field intensity, requires that on the receiving side the loudness be not subject to variations. Since the loudness for a constant amplitude of the modulation frequency depends on the modulation degree the problem here is to keep constant the amplitude of the frequency which is to be modulated. In order, moreover, to obtain a large range of transmission, while ensuring that the transmitter be well utilized, the transmitter is modulated very intensely, namely 'to a degree beyond 90%.
  • a modulation frequency employed for characterizing the beacon such as a frequency of say 1000 c. p. s.
  • the amplitude of the carrier frequency however is less easy to maintain constant. If now for instance the amplitude of the carrier frequency decreases while the modulation frequency continues to be of a constant amplitude, then an overmodulation occurs because as stated a very intense modulation is provided'for. Although in this way the transmitter will not in any case be fully overmodulated yet at least harmonies or over-tones will occur, which interfere very seriously with the navigation.
  • pre-signals are employed with radio beacons, such pre-signals being based for instance on the same wavelength while working with different characteristic tones.
  • prez-signals serve for example to characterize the commencement of the landing or serve to indicate the boundary of the landing ground. If now harmonic waves arrive due to overmodulation of the beacon transtioned phenomena of solved by controlling either the bias of a stage connected inadvance of the modulation stage or the bias of the modulation stage itself.
  • Fig. 1 being a diagrammatic representation of one of these embodiments
  • Fig. 2 a diagrammatic representation of the other embodiment, v
  • Figs. 2a and 2b represent modifications of Fig. 2, only so much of the circuit of Fig. 2 being represented as is necessary to illustrate the modifications therein.
  • Fig. 1 the first three stages I, II, III of a multistage transmitter are shown.
  • the first stage I is arranged to operate with I quartz control; in the second stage II a control for effecting the constancy of the modulation degree is active, while in the grid circuit of the third stage III the modulation is effected.
  • the modulation frequency is impressed over the transformerT upon the push-pull tubes Rm by grid voltage modulation.
  • an inductance L1 is connected which islocated in the grid circuit of the next stage.
  • the inductance Ina rectifier G which in the case represented is a tube the grid of which is connected to the anode, is coupled.
  • the rectified voltage is used for controlling the grid bias of the second stage over a condenser Cg and a choke Dg.
  • the control is efiected with the aid of the resistance V- and W. Included in series with V is a choke D11. At GV a constant negative bias is given.
  • the other parts represented in the 5 drawings are well known. They have per se nothing to do with'the invention.
  • the mode of action of the arrangement is as follows:
  • the modulation frequency arriving over T is practically constant.
  • the carrier frequency already modulated is rectified in the output cir-- cult of the third stage by the rectifier G.
  • the resultant continuous voltage is a means for measuring the magnitude of the carrier, for as is well known the mean value of a modulated oscillation does not vary if the transmitter is otherwise constant.
  • the voltage relations are now so selected that the grid bias of the stage II shall always be So controlled that the carrier amplified in stage 11 shall always/be of the same magnitude. The only requirement is that the control is effected in a stage in which the magnitude of the carrier alone can be influenced, as otherwise the menover-modulation cannot be avoided.
  • control may of course be used. Furthermore, the control may of course be effected in another manner customary in the high frequency art.
  • Fig. 2 four stages of a multistage transmitter are shown.
  • stage I a quartz control is employed.
  • stage II a control for efiecting the constancy of the modulation degree is active, whilst in the grid circuit of the stage IV the modulation is accomplished.
  • the continuous control voltage is derived by the rectifier G.
  • the modulation frequency is impressed over 'the transformer T upon the push-pull tubes RIV by grid voltage modulation.
  • the rectifier G is coupled through a condenser C.
  • the continuous voltage which the rectifier G produces at the resistance W across the choke coil D1 is laid, for instance through a resistance V and a choke D3, to the grid of the tube of stage II.
  • the grid of the rectifier tube is caused by the condenser K to have the same high frequency potential as has the anode, and hence is short-circuited with respect to the high'frequency.
  • a constant continuous voltage is given to the grid of the rectifier.
  • the grid bias of the stage II i. e. the grid bias having to be regulated in order to ensure a reliable operation of the transmitter, and the setting or adjusting of the rectifier working point, would not be independent of each-other.
  • the bias on the grid of the rectifier may be controlled continuously, such as by the modulation tone or independency upon the network voltage.
  • the modulation tone or independency upon the network voltage.
  • one has to rectify the modulation tone and to employ the resultant continuous voltage for controlling the grid.
  • FIG. 2a schematically illustrates a modification of Fig. 2 suitable for embodying this feature of the invention.
  • G2 represents rectifying means connected to rectify a portion of the tone frequency supplied across the primary of transformer T. It will be noted that the output of such rectifying means is applied to the grid return lead of rectifier tube G, thus replacing the grid bias source schematically represented by -G.V in Fig. 2.
  • Fig. 212 represents another embodiment of a plicants invention wherein the bias of rectifier tube G is controlled by the same method but with respect to variations in the network voltage rather than with respect to variations in the amplitude of the tone.
  • the rectifying means G2 is connected in similar manner to the rectifying means G2 previously described, but the input thereof is fed by the network voltage rather than by the tone frequency across transformer T. This arrangement thereforserves to compensate for variations of network voltage rather than for variations of amplitude of the tone.
  • a modulating system comprising carrier current producing means, a carrier current amplifier tube having a control grid, modulating means connected to the output of said amplifier tube, a rectifier tube having a control grid and an anode arranged to rectify a portion of the unmodulated output current of said amplifier tube, means for causing resulting rectified current to apply a corrective bias to the grid of said amplifier tube to hold constant the amplitude of said carrier current, means to cause said control grid of said rectifier tube to have the same high frequency potential as said anode whereby the adjustment of the rectifier to a desired working point can be effected independently of the adjustment of the normal grid-bias of said amplifier tube, and means for giving the said control grid a continuous current bias;

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US218466A 1935-02-05 1938-07-09 Modulated high frequency transmitter system Expired - Lifetime US2212568A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB16595/35A GB445071A (en) 1935-02-05 1935-06-07 Improvements in transmitters for radio beacons
FR794087D FR794087A (fr) 1935-02-05 1935-08-21 Procédé de modulation d'émetteurs modulés en audio-fréquence
US218466A US2212568A (en) 1935-02-05 1938-07-09 Modulated high frequency transmitter system

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE445071X 1935-02-05
US37122A US2151921A (en) 1935-02-05 1935-08-21 Method of modulating high frequency transmitters
US218466A US2212568A (en) 1935-02-05 1938-07-09 Modulated high frequency transmitter system

Publications (1)

Publication Number Publication Date
US2212568A true US2212568A (en) 1940-08-27

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Family Applications (1)

Application Number Title Priority Date Filing Date
US218466A Expired - Lifetime US2212568A (en) 1935-02-05 1938-07-09 Modulated high frequency transmitter system

Country Status (3)

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US (1) US2212568A (fr)
FR (1) FR794087A (fr)
GB (1) GB445071A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2564928A (en) * 1947-01-24 1951-08-21 Wurlitzer Co Amplitude modulated telemetering system
US2591732A (en) * 1945-03-05 1952-04-08 Sheaffer Charles Radio apparatus
US2651757A (en) * 1950-07-07 1953-09-08 Marconi Wireless Telegraph Co Modulation control circuits for modulated carrier wave transmitters

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2591732A (en) * 1945-03-05 1952-04-08 Sheaffer Charles Radio apparatus
US2564928A (en) * 1947-01-24 1951-08-21 Wurlitzer Co Amplitude modulated telemetering system
US2651757A (en) * 1950-07-07 1953-09-08 Marconi Wireless Telegraph Co Modulation control circuits for modulated carrier wave transmitters

Also Published As

Publication number Publication date
GB445071A (en) 1936-04-02
FR794087A (fr) 1936-02-07

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