US2110046A - Broadcasting with reduced band width - Google Patents

Broadcasting with reduced band width Download PDF

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Publication number
US2110046A
US2110046A US54359A US5435935A US2110046A US 2110046 A US2110046 A US 2110046A US 54359 A US54359 A US 54359A US 5435935 A US5435935 A US 5435935A US 2110046 A US2110046 A US 2110046A
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United States
Prior art keywords
band
modulator
carrier
notes
broadcasting
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Expired - Lifetime
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US54359A
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English (en)
Inventor
Koomans Nicolaas
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Individual
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Individual
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Publication of US2110046A publication Critical patent/US2110046A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/68—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission for wholly or partially suppressing the carrier or one side band
    • 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 mv'enfian relates toli'as inethodzemote casting: and tozatransmitter! in. which: a; modulatedi wave is: radiated; said wave comprising i as cai rier and two sidebands; onerof saidside bands "being i I completei 'andrthe other: containing only;
  • such alwave' is: ob-
  • quency' nto two:- parts; one of which: comprises 'only 'high; notes,- the other partcontaining the remaining ⁇ low notes. I The: low; notes; are. then: modulated according to the usual: two sid'e band niethodgjan'd the high notes according toithe single si'cle-band method, the--- carrier frequency products of modulation are added'.
  • T-heinventionl is' the outcome of attempts to reduce -the actual over-crowdinginthe" ether.
  • A' well known 'proposal to obtain such a reduc tion is 'the suppression of one of the. two side bands in; awave modulated ⁇ according to the a usual t'vv'oside-bandmethod-E
  • the present invention meets these difiiculties by utilizing a system ensuring a considerable 40 reduction in the necessary band-width, but with which at the same time a good quality of communication is possible.
  • a feature of the method of the invention used in this system is that in addition to the carrier wave one side band is 45 sent out completely and the other side band only insofar as the components represent low notes.
  • the low notes of the audiofrequency spectrum to be radiated will be represented in both side bands, and the high notes in 50 one side band only.
  • the first range is modulated in the. usual two-side bandmanneraand the-second range according to a single-side band system.
  • the low notes may thus be modulated in ausual manner, which does not 'giverise to difiiculties, and the high notes may be directly modulated on a carrier of comparatively high f requency without consequent' difiicultie's relating to the-filtering off one side bandffromthe resulting mixture;
  • said high frequency carrier may be intermediate or alternatively may itself be the carrier t0-beradiatedj dependent on circumstances; such as the'wave-length on which the. modulation is; ef Q:
  • the two-side-band modulation of the low notes it is advisable to arrange suitably for the two-side-band modulation of the low notes to be flat, so that the single-side-band modulated high notes may be added without carrier wave; in other words the surplus of carrier in the twoside-band modulated part serves as the carrier in the single-side-band modulation.
  • the depth of modulation will be so chosen that a suificient carrier amplitude is obtained for the entire wave this carrier will have the required phase.
  • Fig. 1 the abscissae represent frequencies and the ordinates amplitudes. The location of the carrier frequency is indicated. This fre-.
  • Fig. 2 shows a diagram of a transmitteradapted to realize the wave form shown in Fig. 1.
  • the transmitterof Fig.2 modulates in two stages, the first *carrier ffrequency being 15 kc. and .the second he; modulation is. by an,
  • the audio-frequency. band extending from 0-7, k. c. in. the mannershown in Fig. 1, so that the resulting wave: comprises frequencies extending fr0m,15+1452 k. c. to 15+145+7 k. c., that is from 158-167 k. ,c., the carrier frquency being k. 0;
  • theaudio-frequencies entering at l are amplified in two paralleled amplifiers land. 3, the amplifier 2 being provided with a band-pass filter from 0-2 k. c. and amplifier 3 having'a band-pass filter from 2-7 k. c. I
  • the output from amplifier 2 is ,modulated in modulator :4, theoutput from amplifier'3 in modulator 5,
  • each-of these modulators being supplied by carrier from generator 6 at- 15 k. c.; the modulators are provided with output band'filters as shown,
  • the output from modulator 4 comprises two side-bands and that from modulator 5 only 'Ihrough the volume control ll] the outputs from amplifiers ll and 9 are supplied to the final modulator I I, supplied from the generator 1 with carrier at 145 k. c. The output from modulator.
  • Method of broadcasting comprising the steps of amplifying a section of the audio-band to be modulated, this section comprising lower frequencies, and separately amplifying the remaining part of the audio-band comprising higher frequencies, modulating the first-named section in a two-side band modulator and the second section in asingle-sideeband-modulator, amplifying the modulation products to different ampli- V tudes, and adding the modulation products. quency is modulated in the example with audio- 2.
  • Method of broadcasting comprising modulating a section of the audio-band containing only notes below a given frequency in a first modulator on a given carrier frequency and the remaining section of the audio-band on the same carrier in a second modulator, the first modulator being a two-side band modulator and the second modulator a single side band modulator, differently amplifying the modulation products, and radiating the said products.
  • Method of broadcasting comprising modulating a section of the audio-band containing only notes below a given frequency in a first modulator on a low carrier frequency and the re-.
  • the first modulator being a two-side band modulator and the sec-, ond modulator a single side band modulator, differently amplifying the modulation products, modulatingthe products of modulation of the first and second modulators on a third modulator operating at a higher carrier frequency, and radiating the products'of modulation of this mod ulator.
  • Broadcast transmitter comprising a path for low audio frequencies and a path forthe remaining audio-frequencies, the first-mentioned path including a double side-band modulator for modulating the low audio-frequencies on a carrier, the second path including a single side-band modulator for modulating the remaining frequencies on a carrier of the same frequency,

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Transmitters (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
US54359A 1934-12-14 1935-12-14 Broadcasting with reduced band width Expired - Lifetime US2110046A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL450000X 1934-12-14

Publications (1)

Publication Number Publication Date
US2110046A true US2110046A (en) 1938-03-01

Family

ID=19786302

Family Applications (1)

Application Number Title Priority Date Filing Date
US54359A Expired - Lifetime US2110046A (en) 1934-12-14 1935-12-14 Broadcasting with reduced band width

Country Status (5)

Country Link
US (1) US2110046A (sr)
DE (2) DE690539C (sr)
FR (1) FR799320A (sr)
GB (1) GB450000A (sr)
NL (1) NL39464C (sr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2719955A (en) * 1952-01-02 1955-10-04 Du Mont Allen B Lab Inc Transmission system
US3492580A (en) * 1965-05-05 1970-01-27 Cit Alcatel Suppressed carrier vestigial-sideband communication system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2719955A (en) * 1952-01-02 1955-10-04 Du Mont Allen B Lab Inc Transmission system
US3492580A (en) * 1965-05-05 1970-01-27 Cit Alcatel Suppressed carrier vestigial-sideband communication system

Also Published As

Publication number Publication date
DE690539C (de) 1940-04-27
GB450000A (en) 1936-07-08
FR799320A (fr) 1936-06-11
DE736530C (de) 1943-06-24
NL39464C (sr)

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