US1545541A - Tandem-operated echo suppressor - Google Patents

Tandem-operated echo suppressor Download PDF

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Publication number
US1545541A
US1545541A US723802A US72380224A US1545541A US 1545541 A US1545541 A US 1545541A US 723802 A US723802 A US 723802A US 72380224 A US72380224 A US 72380224A US 1545541 A US1545541 A US 1545541A
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US
United States
Prior art keywords
suppressor
transmission
circuit
circuits
tandem
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
US723802A
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English (en)
Inventor
Sumner B Wright
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.)
AT&T Corp
Original Assignee
American Telephone and Telegraph Co Inc
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
Application filed by American Telephone and Telegraph Co Inc filed Critical American Telephone and Telegraph Co Inc
Priority to US723802A priority Critical patent/US1545541A/en
Application granted granted Critical
Publication of US1545541A publication Critical patent/US1545541A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/20—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/04—Control of transmission; Equalising
    • H04B3/10—Control of transmission; Equalising by pilot signal

Definitions

  • This invention relates to transmission 'circuits, and more particularly to transmission circuits employing echo suppressors.
  • One of the objects of the invention is to provide an arrangement whereby two or more circuits, each equipped with echo sup pressors, may be operated intandem.
  • the problem presented when two or more circuits, each having an echo suppressor, are switched together, is to prevent the cir cuits getting into such a condition that, when two subscribers at the ends begin to talk at about the same timc,.neithcr subscriber will be able to hear the other.
  • the echo suppressor uiiitffor shorten-coil ing the path transmitting west will be disablcd in the case of the one circuit. and the echo suppressor unit for short-circuiJ ing the path transmitting east will be disabled in thc rasc of the other transmission circuit. Under 'oll' transmission suppressor near end it while 7 SUPPRESSOR.
  • Fig. 2 illustrates'a similar pair of tour-wire repeater circuitsprovided with means for disabling certailrof the echo suppressor units in accordance with the present in vention; 4
  • a four-wire circuit is schematically shown, said circuit being equipped with the usual one-way repeaters and an echo su ipress'or-between stations A and l5, while a similar circuit is shown between stations l3 and G.
  • ncctiims'over either circuit each individual echo suppressor tunctions in its normal man nor, that. is, when transmission takes place from.
  • a to B the A--l3 suppressor operates and slmrt-cirmaits the opposite branch of the tour-wire circuit, suppressing echoes from I5, and vice versa.
  • a Fig. 2 shows. schematically.
  • the toll cord establishes the connection between the two four-wire circuits in tandem, a ground is connected to thesleeve conductor of the line jack of the four-wire circuit extending from station A to station B, thereby causing current to flow through .
  • a control wire (which may be a simplex or composite circuit of any well-known type, if desired) to operate a relay X atthe fourwire repeater station at which the echo suppressor A-B is applied.
  • This relay renders the AB half 'of the echo suppressor inoperative by opening the shortcircuit controlled by the AB half of the sup-- pressor, the B-A half of the suppressor, however, remaining in its normal condition.
  • the C-B half of the echo suppressor on the circuit between B and C is rendered inoperative when the other end of I l the toll cord is inserted in the line jack at B by means of a ground applied to another similar control wire to operate the relay Y.
  • the B-C half of the suppressor is not disabled, however, as the relay W remains normal because the sleeve at C j is not grounded.
  • the resulting effect is, therefore, that of a four-wire circuit equipped with a single 'eeliosuppressor arrangement, the two halves of which are located not near the center of the circuit but one near the receiving en for each direction. Consequently, when the subscriber at'A talks to the subscriber at C, the voice currents will ,be transmitted through station over the upper lines of wire ciicii mils west,
  • each four-wire circuit and upon arriving at the point where the echo suppressor B-C is applied, ..the latter suppressor. will be opcrated'to' short-circuit the line of the fourit between B. and C which trans- This prevents C to A so that echo currents transmitted through the, hybrid coil at C cannot be propagated back to station
  • Theline trainsn'i'itiing w cstbelwccn stations A and B is, of cm'u'se, not disabled so that anyrclm currents which pass through the hybrid coil of the four-wire circuit bet een A and B at station ever, may
  • the method above described is applicable to circuits built up of more than two fourwire repeater circuits equipped with individual echo suppressors. For example, it will be apparent that if a connection be C to a third four-wire circuit established at by means of a toll cord connection similar to that shown at -B,.the relay W would be operated to disable the suppressor unit'B C and its place would be taken by half of another suppressor located at a point beyond Similarly, if a connection is established at A to another four-wire circuit, the relay Z *"ill be operated to disable the suppressor nit BA, its place in turn being taken by one-half of a suppressor unit located beyond A. It will be understood, of course, that where connections are to be.
  • a transmission system a plurality of transmission circuits adapted to be connect ed in tandem, a pair of echo suppressor units associated with each circuit, one being responsive to currentstransmitted in one direction for disablingthecircuit for transmission in the opposite direction, being responsive to currents transmitted in the opposite direction for disabling thecircuit for transmission in the'first direction, and means operating upon the connection of said circuits in tandem to render all of said echo suppressor units ineffective except-one pair, of which one will be responsive to ourother responsive to currentstransmitted in the opposite direction.
  • a plurality of transmission circuits adapted tobe connectlllll the other V I sponsive to currents transmitted in one direction-Ior disabling the circuit for transmission in theopposite direction, the other being responsive to currents transmitted in the opposite direction for disabling the circuit for transmission in the first direction,
  • a transmission system a plurality of transmission circuits adapted to be connected in tandem, a'pairof echo suppressor units associated with each circuit, one being re sponsive to currents transmitted in one direction for disabling the circuit-for transmission in the opposite direction, the other being responsive to currents transmitted in the opposite direction for disabling the circuit for transmission in the first direction,
  • a plurality of transmission circuits adapted to be connected in tandem a pair of echo suppressor units associated wlth each circuit, one being responsive to currents transmitted in one direction for disabling the circuit for transmission in the opposite direction, the other being responsive to currents transmitted in the opposite direction for disabling the circuit for transmission in the first direction, means to connect said transmission circuits in tandem, and circuits controlled by said with one of said transmission circuits and responsive to currents transmitted in one direction and another unit associated with another of said transmission circuits and responsive to currents transmitted in the oppositedirection.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
US723802A 1924-07-02 1924-07-02 Tandem-operated echo suppressor Expired - Lifetime US1545541A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US723802A US1545541A (en) 1924-07-02 1924-07-02 Tandem-operated echo suppressor

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US723802A US1545541A (en) 1924-07-02 1924-07-02 Tandem-operated echo suppressor
GB27117/24A GB245554A (en) 1924-11-13 1924-11-13 Improvements in or relating to telephone repeater circuits

Publications (1)

Publication Number Publication Date
US1545541A true US1545541A (en) 1925-07-14

Family

ID=10254473

Family Applications (2)

Application Number Title Priority Date Filing Date
US723802A Expired - Lifetime US1545541A (en) 1924-07-02 1924-07-02 Tandem-operated echo suppressor
US723796A Expired - Lifetime US1545558A (en) 1924-07-02 1924-07-02 Tandem-operated echo suppressor

Family Applications After (1)

Application Number Title Priority Date Filing Date
US723796A Expired - Lifetime US1545558A (en) 1924-07-02 1924-07-02 Tandem-operated echo suppressor

Country Status (6)

Country Link
US (2) US1545541A (enrdf_load_stackoverflow)
CH (1) CH113647A (enrdf_load_stackoverflow)
DE (1) DE474670C (enrdf_load_stackoverflow)
FR (1) FR596065A (enrdf_load_stackoverflow)
GB (1) GB245554A (enrdf_load_stackoverflow)
NL (1) NL15798C (enrdf_load_stackoverflow)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2990457A (en) * 1958-02-04 1961-06-27 Bell Telephone Labor Inc Tandem echo suppressor circuits

Also Published As

Publication number Publication date
DE474670C (de) 1929-04-12
CH113647A (fr) 1926-02-16
NL15798C (enrdf_load_stackoverflow) 1927-01-15
US1545558A (en) 1925-07-14
GB245554A (en) 1926-01-14
FR596065A (fr) 1925-10-15

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