US2429683A - Modulation - Google Patents

Modulation Download PDF

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Publication number
US2429683A
US2429683A US480184A US48018443A US2429683A US 2429683 A US2429683 A US 2429683A US 480184 A US480184 A US 480184A US 48018443 A US48018443 A US 48018443A US 2429683 A US2429683 A US 2429683A
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United States
Prior art keywords
frequency
modulation
modulated
frequencies
circuit
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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
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US480184A
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English (en)
Inventor
Haantjes Johan
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.)
Hartford National Bank and Trust Co
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Hartford National Bank and Trust Co
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Publication date
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    • 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

  • the invention relates to a system for a modulating high-frequency oscillations wherein one of the side-bands is suppressed, at least partially.
  • Fig. 1 represents a carrier oscillation modulated in amplitude by a single sine-shaped oscillation.
  • Fig. 2 represents the carrier oscillation modulated by the same sine-shaped oscillation, one side-band being suppressed. Upon comparing these two figures, it is clearly visible that in both cases the modulation envelopes of the transmitted oscillations are quite different.
  • the voltage obtained after detection does consequently not correspond to the sinusoidal voltage obtained upon reception of the oscillations represented in Fig. 1.
  • the invention has for its object to provide a modulation system wherein a, single side-band is suppressed either wholly or partially and With which it is ensured in a simple manner that with linear detection the modulated signal yields an undistorted modulation voltage.
  • modulation is effected by supplying the oscillation to be modulated to a network with at least part of which the series connection of a rectifier, a resistance bridged for alternating current and the source of modulating voltage is connected in parallel wherethat complicated devices are necessary for ensuras the modulated oscillation is taken from this series connection and the said network has such a characteristic of the impedance as a function of frequency that for frequencies of the side-band portion to be suppressed substantially no impedance is present.
  • Figs. 1 and 2 represent already discussed shapes of the modulation envelope in the case of double and single side-band modulation respectively.
  • Fig. 3 represents an embodiment of a circuit arrangement according to the invention.
  • Fig. 4 shows the characteristic of the impedance of the resonant circuit of Fig. 3 as a function of frequency.
  • the modulation envelope has a shape which points to th presence of a strong harmonic.
  • the modulation envelope produced in the case of single side-band transmission of a signal modulated by two frequencies qi and qz has a shape which indicates the presence of combination frequencies q1+q2 and (Ir-Q2.
  • the second harmonics and any existing combination frequencies are suppressed by adding a high-frequency correction voltage whose enveloping curve comprises the second harmonics and any existing combination frequencies of the modulation frequencies in a phase opposite to that of the second harmonics and combination frequencies in the enveloping curve of Fig. 2.
  • the high-frequency oscillation to be modulated is supplied to an oscillatory circuit constituted by an inductance L and a capacity C.
  • a series circuit consisting of a diode 2, the parallel connection of a resistance R and a condenser C1 which constitutes a short circuit for the modulation frequency, and the source of modulating voltage 3.
  • the modulated high-frequency voltage may be taken from output terminals 1.
  • the oscillatory circuit LC is tuned to a frequency which differs from the frequency of the oscillation to be modulated.
  • the characteristic of the impedance as a function of frequency is shown in Fig. 4 wherein or represents the frequency of the oscillation ,to be modulated and p represents the highest modulation frequency.
  • the frequency q is modulated on the carrier wave with :a depth of modulation m the'depth of modulation m2q for the second harmonic 2; which is compensated for thegreater part owing to the presence of the said correction frequency w-2q amounts in the enveloping curve to:
  • the depth :of modulation amounts without correction for the second'harmonic 7712!; to V mq2.
  • the correctedion frequency w-l-2g' is located outside the frequency range to be trans- :mitted where'the circuit LC has alow impedance so that :this frequency does not occur.
  • the second harmonic of the modulating voltage which occurs due'to the side-band suppression in the low-frequency amplifierof the :receiver, is also located outside the frequency range to be transmitted and may easily be suppressed by an adequate choice of the frequency characteristic of the low-frequency amplifier.
  • circuit LC instead of the circuit LC use may-be made of a more complicated network in order to obtain the desired steep flank of the impedance curve according to Fig. 4.
  • a source of wave energy to'be mo'dulated a source of modulating potentials
  • a circuit tuned to a frequency different than the frequency of wave energy from said source a rectifier and said source of modulating potential series connected in parallel with said tuned circuit, means for impressing said wave energy to be modulated on said tuned circuit, and means for deriving modulated wave energy from said rectifier.
  • a source of oscillation to be modulated a source of modulating voltage, a network, a rectifier, a resistance bridged for alternating current and said source of modulating voltage series connected in parallel with a part at least of said network,and means for deriving the modulated oscillation from the series connection, said network having such a characteristic of impedance as a function of frequency that for frequencies of the sideband portion to be suppressed substantially no impedance is present;
  • rectifier is a two-electrode rectifier operated as a peak detector.

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  • Amplitude Modulation (AREA)
  • Gyroscopes (AREA)
  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
  • Oscillators With Electromechanical Resonators (AREA)
US480184A 1940-06-12 1943-03-23 Modulation Expired - Lifetime US2429683A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL601397X 1940-06-12

Publications (1)

Publication Number Publication Date
US2429683A true US2429683A (en) 1947-10-28

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ID=19787795

Family Applications (1)

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US480184A Expired - Lifetime US2429683A (en) 1940-06-12 1943-03-23 Modulation

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US (1) US2429683A (enrdf_load_html_response)
DE (1) DE756734C (enrdf_load_html_response)
GB (1) GB601397A (enrdf_load_html_response)
NL (1) NL63056C (enrdf_load_html_response)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4703273A (en) * 1985-07-29 1987-10-27 The United States Of America As Represented By The United States Department Of Energy 140 GHz pulsed fourier transform microwave spectrometer

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE949668C (de) * 1954-03-11 1956-09-27 Rundfunk Tech I G M B H Verfahren zur Verringerung der nichtlinearen Verzerrung bei Restseitenbanduebertragung
DE1165104B (de) * 1959-06-16 1964-03-12 Fernseh Gmbh Verfahren und Anordnung zur weitgehenden Kompensation der bei der Restseitenbanduebertragung auftretenden Signalfehler

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1592710A (en) * 1920-07-17 1926-07-13 Scott-Taggart John Modulation system
US2129820A (en) * 1936-07-23 1938-09-13 Bell Telephone Labor Inc Modulation system for ultra-short waves
US2305911A (en) * 1940-12-21 1942-12-22 Int Standard Electric Corp High efficiency loss modulator
GB550899A (en) * 1941-10-07 1943-01-29 Philips Nv Improvements in or relating to systems for modulating high-frequency oscillations with the suppression at least partially of one of the side-bands

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2048080A (en) * 1934-02-10 1936-07-21 American Telephone & Telegraph Signaling with high frequency waves

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1592710A (en) * 1920-07-17 1926-07-13 Scott-Taggart John Modulation system
US2129820A (en) * 1936-07-23 1938-09-13 Bell Telephone Labor Inc Modulation system for ultra-short waves
US2305911A (en) * 1940-12-21 1942-12-22 Int Standard Electric Corp High efficiency loss modulator
GB550899A (en) * 1941-10-07 1943-01-29 Philips Nv Improvements in or relating to systems for modulating high-frequency oscillations with the suppression at least partially of one of the side-bands

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4703273A (en) * 1985-07-29 1987-10-27 The United States Of America As Represented By The United States Department Of Energy 140 GHz pulsed fourier transform microwave spectrometer

Also Published As

Publication number Publication date
DE756734C (de) 1953-09-07
NL63056C (enrdf_load_html_response)
GB601397A (en) 1948-05-05

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