US2185874A - Arrangement for amplitude modulation - Google Patents

Arrangement for amplitude modulation Download PDF

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Publication number
US2185874A
US2185874A US95519A US9551936A US2185874A US 2185874 A US2185874 A US 2185874A US 95519 A US95519 A US 95519A US 9551936 A US9551936 A US 9551936A US 2185874 A US2185874 A US 2185874A
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Prior art keywords
energy
bridge
tube
modulation
arrangement
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Expired - Lifetime
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US95519A
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English (en)
Inventor
Urtel Rudolf
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Telefunken AG
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Telefunken AG
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
    • C08H8/00—Macromolecular compounds derived from lignocellulosic materials
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G10/00—Condensation polymers of aldehydes or ketones with aromatic hydrocarbons or halogenated aromatic hydrocarbons only
    • C08G10/02—Condensation polymers of aldehydes or ketones with aromatic hydrocarbons or halogenated aromatic hydrocarbons only of aldehydes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L97/00—Compositions of lignin-containing materials
    • C08L97/02—Lignocellulosic material, e.g. wood, straw or bagasse
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C1/00—Amplitude modulation
    • H03C1/16—Amplitude modulation by means of discharge device having at least three electrodes
    • H03C1/18—Amplitude modulation by means of discharge device having at least three electrodes carrier applied to control grid
    • H03C1/22—Amplitude modulation by means of discharge device having at least three electrodes carrier applied to control grid modulating signal applied to same grid

Definitions

  • the invention relates to an arrangement for amplitude modulation in which the value of the sum of two alternating currents of equall frequency is formed, and one or both partial currents are varied about an average value by one of several modulation voltages by means for inuencing the degree of amplification cfa controlled discharge tube.
  • modulation ycircuits which may be designated as tube bridge circuits, were found in the past to be extremely unstable in operation. Therefore in practice, such tube bridges for modulation purposes have not found use, and other modulation arrangements have been resorted to.
  • VThis invention overcomes the instability hitherto observed ⁇ in tube bridging circuits, which is due to the amplifier tubes proper, and which apparently has its origin in the fluctuations of the emission of the tube cathodes. when measured on the mean emission amperage of the cathode.
  • FIG. 1 shows a schematic circuit showing the means and method of stabilizing tube bridges
  • Fig. 2 shows a graphical analysis of the circuit operation for explaining the invention
  • Fig. 3 shows a modification, of one of the circuit elements of Fig. 1 useful for television
  • Fig. 4 shows a block diagram of a modification These fluctuations are however small But in tube bridges they pro- I prise a disturbing phenomenon because of the fact that the difference current of the bridgeon which the modulation arrangement principallyV lel resonance circuit 8 tuned to the carrier frequency appliedto the primary winding of the transformer I2.
  • Item Il' represents a high-frequency amplifier which amplies the entire band, and to which a detector ⁇ I9 is coupled by a transformer it.
  • the detector circuit contains a yresistor 2B, a condenser 2l and afurther arrangement serving for filtering out the modulation potentials and consisting of a condenser 22 and a resistor 23.'
  • the point P is connected to the.
  • Thearrangement according toFig. 1 operates such that there will be applied to the control grid I of the tetrode Ill the modulation frequencies corresponding to the brilliancy of the picture point, and which may be derived for ⁇ instance from any picture scanning means.
  • the two control grids 2 situated next to the anode alterl hating potentials exist in opposite phase which.4
  • the voltage appearing at ⁇ the parallel resonance circuit will be amplified, ⁇ then detected by the arrangement I9 to 23 showing a rectifier and lter, and deprived of the modulation frequencies by suitable choice of constants for the condensers 2
  • the potential appearing at point AP thus Varies in accordance with the variable emission of the two tubes.
  • This potential is applied, through a compensation voltage source 24, to the grid I of tube II, land hence influences the amplification of this tube such that the fluctuation of the input potential of the ampliiier II produced by variation in the emission will be compensated almost entirely.
  • Fig. 1 The functioning of the circuit according to Fig. 1 can be explained graphically by means of the tube characteristics shown in Fig. 2.
  • Fig. 2 there is shown in relation to the voltage ci at the grid I of tube Il, the input voltage e2 of the high-frequency amplifier il.
  • the bridge may be completely balanced at the value e1 at the grid of tube I8. Therefore, the carrier-frequency potential at the parallel resonance circuit is zero.
  • c1 the equilibrium of the bridge is disturbed, so that a carrier frequency appears at the parallel resonance circuit having the amplitude shown as ordinate of the line course a, b, c.
  • the carrier frequency amplitude at the input of the amplifier Il would vary, i. e. the voltage ez would Vary between the values e2 and 62', if however as proposed in accordance with the invention, a potential is applied to the grid I of tube II, consisting of the compensation voltage ek and of the voltage es at point P, then only an unlike lower fluctuation of the voltage c2 occurs. This can be readily seen when marking the voltage e2 at the* abscissa in Figure 2, and observing that the cotangent of angle corresponds to the v ratio between the voltage e3 and the voltage e2.
  • FIG. 2 shows that at a decrease of the value ek, the working point moves downwards on the right hand branch of the bridge characteristic, andy moves4 upwards with an increase-of ek.
  • a bridge arrangement of the type described alsoaffords the transmission of other signals in an especially simple manner than those corresponding to the picture brilliancy, such as for instance line and picture alternation signals. If the line and picture alternation pulses are to be sentout by means of a shorter or longercomplete interruption of the carrier wave, it is only necessary to take care that for the transmission of completely black picture points, the bridge arrangement .is not modulated to the value @2:02-
  • the tube bridge isdesignated by 28
  • the carrier wave generator is represented by 29
  • the keying. stage is designated by 30, and may consist for-instance of a hexode which has the keyed .potential applied to one of its control grids.
  • is a generator for the synchronizing pulses, and 32, 33 are saw tooth generators of a cathode ray picture scanning means 34.
  • the currents furnished bythis generator are fed across an amplier 35 into the grid i of tube I0 in the bridge in Figure 1.
  • the control arrangement for the continuous adjustment of the working point of the bridge is omitted in Figure 4.
  • the modulation arrangement proposed according to the invention may also be utilized for the By this is meant a modulation method in which for the purpose of saving transmitter energy, the high frequency amplitude is always adjusted to a value approximately proportionalV to the amplitude of the modulation voltage.
  • the carrier frequency amp-litude is-small and vice versa.
  • the compensation voltage and hence, the carrier frequency amplitude isl to be rendered dependent upon the amplitude of the modulation voltage.
  • the method of stabilizing the balance or" the bridge against fortuitous unbalancing which comprises producing energy in accordance with fortuitous unbalancing of the bridge, and balancing the bridge with the produced energy.
  • the method of stabilizing the balance of the bridge against fortuitous unbalancing which comprises deriving from the bridge carrier Wave energy modulated by both signalling energy and spurious energy, deriving energy from the last mentioned energy representative only of the spurious modulated energy, and balancing the bridge with the second mentioned derived energy.
  • the method of stabilizing the balance of the bridge against fortuitous unbalancing which comprises .deriving from the bridge carrier wave energy modulated by both signalling energy and spurious energy, rectifying the derived carrier Wave energy, ltering out a component of the rectified energy representative only of the spurious energy, and balancing the bridge in accordance with the filtered component of energy.
  • a stabilized balanced bridge modulator comprising means for producing energy in accordance with fortuitous unbalancing of the bridge, and means for balancing the bridge with the produced energy.
  • a stabilized balanced bridge modulator comprising means for deriving from the bridge carrier Wave energy modulated by both signalling energy and spurious energy, means for deriving energy from the last mentioned energy representative only of the spurious modulated energy, and means for balancing the bridge with the second mentioned derived energy.
  • a stabilized balanced bridge modulator cornprising means for deriving from the bridge carrier wave energy modulated by both signalling energy and spurious energy, means for rectiiying the derived carrier wave energy, means for lter ing out a component of the rectified energy representative only of the spurious energy, and means for balancing the bridge in accordance with the filtered component of energy.
  • the method of stabilizing the balance of the bridge against fortuitous unbalancing which comprises deriving from the bridge carrier wave energy modulated by both signalling energy and spurious energy, rectifying the derived carrier Wave energy, ltering out a component of the rectified energy representative only of the spurious energy, supplying a source of constant energy, and feeding the ltered component of energy in series with the supplied source of constant energy to the bridge to balance the bridge for the spurious energy.
  • a stabilized balanced bridge modulator comprising means for deriving from the bridge carrier Wave energy modulated by both signalling energy and spurious energy, means for rectifying the derived carrier Wave energy, means for iiltering out a component of the rectified energy representative only of the spurious energy, supplying a source of constant energy, and means for feeding. the filtered component of energy in series With the supplied source of constant energy to the bridge to balance the bridge for the spurious energy.
  • the method of modulating carrier Wave energy which comprises the steps of adjusting the bridge to a predetermined balance, deriving energy from the bridge'representative only of spurious modulated energy, re-establishing the balance of the bridge in accordance with the derived energy, and photoelectrically altering the balance of the bridge in accordance With the integrated illumination of an optical representation to be transmitted.
  • a balanced bridge modulator comprising meanslfor adjusting the bridge to a predetermined balance, means for deriving energy from the bridge representative only of spurious modulated energy, means for re-establishing the balance of the bridge in accordance with the derived energy, and means for photoelectrically altering the balance of the bridge in accordance Withvthe integrated illumination of an optical representation to be transmitted.
  • the method of operating a balanced bridge modulator which comprises deriving from the bridge carrier Wave energy modulated by both signalling energy and spurious energy, deriving energy from the last mentioned energy representative only of the spurious modulated energy, balancing the bridge With the second mentioned derived energy, and unbalancing the bridge in accordance with the average value of the signalling energy.
  • a balanced bridge modulator comprising means for deriving from the bridge carrier Wave energy modulated by both signalling energy and spurious energy, means for deriving energy from the last mentioned energy representative only of the spurious modulated energy, means for balancing the bridge with the second mentioned derived energy, and means for unbalancing the bridge in accordance with the average value of the signalling energy.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Materials Engineering (AREA)
  • Biochemistry (AREA)
  • Wood Science & Technology (AREA)
  • Amplifiers (AREA)
US95519A 1935-08-12 1936-08-12 Arrangement for amplitude modulation Expired - Lifetime US2185874A (en)

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DE2185874X 1935-08-12

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2441964A (en) * 1944-05-19 1948-05-25 Standard Telephones Cables Ltd Compensating circuit
US3040274A (en) * 1959-12-28 1962-06-19 Gen Electric Balanced modulator

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2441964A (en) * 1944-05-19 1948-05-25 Standard Telephones Cables Ltd Compensating circuit
US3040274A (en) * 1959-12-28 1962-06-19 Gen Electric Balanced modulator

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