US2328450A - Carrier frequency system - Google Patents

Carrier frequency system Download PDF

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Publication number
US2328450A
US2328450A US414415A US41441541A US2328450A US 2328450 A US2328450 A US 2328450A US 414415 A US414415 A US 414415A US 41441541 A US41441541 A US 41441541A US 2328450 A US2328450 A US 2328450A
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United States
Prior art keywords
band
carrier
conversation
carrier frequency
frequency
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Expired - Lifetime
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US414415A
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English (en)
Inventor
Hagen Wolfgang
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Individual
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Individual
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Publication date
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Publication of US2328450A publication Critical patent/US2328450A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J1/00—Frequency-division multiplex systems
    • H04J1/02—Details
    • H04J1/04—Frequency-transposition arrangements
    • H04J1/045—Filters applied to frequency transposition

Definitions

  • This invention relates to carrier frequency systems of the kind in which two or more wave transmission channels are used.
  • wave filters are arranged to separate each channel from the other channel and also to separate each direction of conversation from the other direction. This entails a large expenditure in filters.
  • one intercommunication band is based on a carrier the lower side-band of which is used for one direction of conversation while the upper sideband is employed for the other direction. Further, as regards a second intercommunication band, one direction of conversation thereof is created by means of the upper side-band of Aa second carrier while for the second direction the lower side-band of a third carrier frequency or both side-bands thereof are used.
  • Fig. 1 illustrates a frequency distribution suitable for carrying out the invention.
  • Fig. 2 graphically represents a lter arrangement for this frequency distribution
  • Fig. 3 is a circuit diagram in which such filter arrangement is included
  • Figs. 4 and 5 are graphs referred to in explaining the function of arrangements as provided by the invention.
  • Fig. 2 the frequency condition of the several transmisison channels can be seen.
  • direction BA thereof is transmitted by the lower side-band K1 while the other or opposite direction, namely AB, is transmitted by the upper side-band K2.
  • the transmission is effected by the upper side-band Ka of the carrier T12 while in direction BA the transmission is by means of the lower side-band K4 or by both side-bands of the carrier Tra.
  • the frequency distribution so obtained results in an expenditure of wave filters which is less than has been the case heretofore.
  • the channels Kz, IQ are both of the same direction.
  • the filters TP1 and HP1, 8, Figs. 2 and 3, hence have to cut olf the cross-talk attenuation only. By transmitting in the same direction no appreciable level differences between .the two lchannels will occur.
  • 'I'he lower side-band of channel KS3 is suppressed by the separating filter HP1, 8 which is effective between the two conversations.
  • the upper channel K4 may be employed for transmitting both side-bands. 'I'his will be of advantage as regards eillciency.
  • the line attenuation increasing in accordance with higher frequencies requires an increased transmitting power to be employed and in its turn acts in a manner similar to a low-pass filter.
  • Fig. 4 shows .the frequency distribution and the curve of line attenuation in the case of a simple two-Way intercommunication
  • Fig. 5 illustrates a frequency distribution suitable in cases where additional carrier frequencies belonging to another system are to be transmitted over the same line.
  • the direction of transmission of the upper conversation includes a modulator M and is accommodated to the line.
  • the call receiving apparatus R is connected by high ohmic resistances in a manner to avoid loss of transmitting energy. Otherwise such loss would occur since the receiving side is connected in parallel with the transmitting side.
  • a changeover switch S1, S2, S3 is provided.
  • the filters HP5.3 and TP4.7 are switched over at contacts S2, Ss while in the case of the upper conversation the carrier frequencies Trz and Tra are interchanged at contacts S1.
  • the switching-over operation is effected with respect to the upper and lower conversations at the same time and in such a manner that the channels located in the middle and which correspond to the reference numerals 2, 3 always operate in the same direction.
  • the two terminal stations may hence be made similar to each other, and by means of switch S1, S2, Sa, they may be adjusted to suit frequency conditions.
  • a low frequency line NF may be connected to the outgoing line over a low pass filter.
  • a carrier frequency system comprising means to produce three diierent carriers, a transmission linemeans to produce from each carrier a lower side-band and an upperside-band,means fortransmitting one direction of a conversation over said line through the lower side-band of one of said carriers while transmitting the other direction thereof over said line by the upper side-band of the same carrier, and means for transmitting one direction of another conversation over sai-d line through the upper side-band of a second carrier while transmitting the other direction thereof over said line by at least the lower side-band of the third carrier.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Radio Relay Systems (AREA)
  • Small-Scale Networks (AREA)
US414415A 1940-03-28 1941-10-10 Carrier frequency system Expired - Lifetime US2328450A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE217893X 1940-03-28

Publications (1)

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US2328450A true US2328450A (en) 1943-08-31

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ID=5831012

Family Applications (1)

Application Number Title Priority Date Filing Date
US414415A Expired - Lifetime US2328450A (en) 1940-03-28 1941-10-10 Carrier frequency system

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US (1) US2328450A (de)
CH (1) CH217893A (de)
FR (1) FR871107A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2577731A (en) * 1942-02-20 1951-12-11 Int Standard Electric Corp High-frequency traffic system over power supply lines
US2695927A (en) * 1951-12-29 1954-11-30 Bell Telephone Labor Inc Multichannel carrier telephone system
US4402076A (en) * 1980-05-15 1983-08-30 Bayly Engineering Limited Two wire F.D. multiplex system
US4996709A (en) * 1988-05-12 1991-02-26 Tandy Corporation Intercom telephone

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2577731A (en) * 1942-02-20 1951-12-11 Int Standard Electric Corp High-frequency traffic system over power supply lines
US2695927A (en) * 1951-12-29 1954-11-30 Bell Telephone Labor Inc Multichannel carrier telephone system
US4402076A (en) * 1980-05-15 1983-08-30 Bayly Engineering Limited Two wire F.D. multiplex system
US4996709A (en) * 1988-05-12 1991-02-26 Tandy Corporation Intercom telephone

Also Published As

Publication number Publication date
CH217893A (de) 1941-11-15
FR871107A (fr) 1942-04-09

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