US2364685A - Telephone system - Google Patents

Telephone system Download PDF

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Publication number
US2364685A
US2364685A US474905A US47490543A US2364685A US 2364685 A US2364685 A US 2364685A US 474905 A US474905 A US 474905A US 47490543 A US47490543 A US 47490543A US 2364685 A US2364685 A US 2364685A
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US
United States
Prior art keywords
line
signalling
frequencies
currents
frequency
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
US474905A
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English (en)
Inventor
Baker George Thomas
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.)
Automatic Electric Laboratories Inc
Original Assignee
Automatic Electric Laboratories 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 Automatic Electric Laboratories Inc filed Critical Automatic Electric Laboratories Inc
Application granted granted Critical
Publication of US2364685A publication Critical patent/US2364685A/en
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q1/00—Details of selecting apparatus or arrangements
    • H04Q1/18—Electrical details
    • H04Q1/30—Signalling arrangements; Manipulation of signalling currents
    • H04Q1/44—Signalling arrangements; Manipulation of signalling currents using alternate current
    • H04Q1/444—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies
    • H04Q1/446—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using one signalling frequency
    • H04Q1/4465—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using one signalling frequency the same frequency being used for all signalling information, e.g. A.C. nr.9 system

Definitions

  • the present invention relates to telephone systems and is more particularly concerned with telephone systems of the type employing, for
  • blocking means normally effective to obstruct the passage over the line of currents of one or more frequencies in the voice frequency range are arranged to be controlled in response to currents of non-signalling frequencies to have their blocking efiect neutralised-
  • the line circuit in a telephone system employing voice frequency currents for the transmission of signals incidental to the setting up and supervision of a connection, includes a filter device adapted to obstruct the passage of currents of the signalling frequency or frequencies and to be rendered inoperative in response to the reception of currents of non-signalling frequencies.
  • the line circuit in a telephone system employing voice frequency currents for the transmission of signals incidental to the setting up and supervision of a connection, is normally blocked to currents of all frequencies and means retransmission of signals in-- sponsive to currents of non-signallingfrequency are arranged to remove the blocking efiect.
  • Fig. 1 shows a line circuit for a voice frequency signalling system, using a filter in the line, for blocking the signalling frequencies, and having an amplifier controlled relay in a branch of the line for removing the blocking effect.
  • Fig. 2 shows schematically an alternate form of the invention using a variable attenuation network in combination with filters.
  • Fig. 3 showsstill another method of operation by the use of a thermal switching device, in conjunction with a filter.
  • Fig. 4 shows a modification of the invention using an echo suppressor in circuit with a filter controlling the operation of the line disabling feature
  • the combination of inductances and capacitances Ll, Cl and L2, C2 represents in simple form a filter of the type necessary to provide high attentuation to a signalling frequency so that the line is in effect blocked to such frequency.
  • Connected across the line by way of a pair of load limiting resistances R! and R2' is an amplifier A, in the input circuit of which a similar filter circuit represented by L3, L4, C3, C4 is inserted so as to ,bar the signallingfrequency.
  • the output circuit of the amplifier is connected to a relay K.
  • a static switching device comprising forinstance dry plate rectifiers or other units the impedance of which can be varied to produce the switching effect brought about by the contacts of relay K.
  • Fig. 2 where the filters FI and F2 are each arranged to offer high impedance to the signalling frequency, while the static switching device SSD which is connected across the line filter Fl and which may comprise a variable attenuation network, normally has a high impedance so that the line is normally blocked to the signalling frequency. If a non-signalling frequency is received either alone or in combination with a signalling frequency, it will pass through filter FI and also by way of filter F2. and the static switching device SSD. The potential change involved in the latter path is used to bias back the switching device SSD so that it now becomes of low impedance and serves to pass all frequencies.
  • a small bead of known material such as uranium oxide or silver sulphide which has a non-linear negative temperature coefficient, that is to say its resistance decreases rapidly from its normal high value with increase of temperature: this will be referred to as a thermal switching device and is designated TSD.
  • the filter F3 which is arranged to offer high impedance to the signalling frequency is connected in series with the heater winding for this device, and hence if a signalling frequency alone is'received it will be unable to pass through since one path therefor'is interrupted by the high resistance of the bead TSD, while the other path is interrupted by virtue of the action of the filter F3. If, on the other hand, a non-signalling frequency alone or accompaniedby the signalling frequency is received, it will be able to find a path by way of the filter F3. Hence the current quencies.
  • Fig. 4 use is made in this instance of an echo suppresser ES which is connected to the line in circuit with the filter F4 which serves to bar the signal frequency. If a signal frequency only is received, the equipment ES will not come into operation and the line will remain blocked, while if a non-signalling frequency is received the echo suppressor comes into An advantage of the above-described arrangements is that since the line is normally blocked to signal frequencies it is impossible for unwanted pips of signal tone to get through to another circuit where trouble might be caused.
  • a line for the setting up and supervision of a signalling and talking connection means normally efiective to obstruct the passage over said line of currents of one or more frequencies in the voice frequency range, and means responsive to currents of non-signalling frequencies to remove said obstruction to allow transmission of said frequencies over the line.
  • a filter tuned to normally obstruct the passage over said line of said currents of the signalling frequency or frequencies, and means for removing said filter obstruction responsive to the transmission of currents of non-signalling frequencies over said line.
  • a line circuit over which voice frequency signalling currents are transmitted during the setting up of a connec tion over the line an amplifier associated with said line, a filter in the inputof said amplifier tuned to make the amplifier unresponsive to said signalling currents but responsive to currents of other frequencies, and means in the output of said amplifier for controlling said line circuit when said other frequencies are received.
  • said last means comprises a relay connected to the output terminals of said amplifier, and adjusted to operate on the transmission of currents of frequencies receptive to said amplifier over said line.
  • a line for the setting up and supervision of a signalling and talking connection, means including a line filter and a shunt normallyiblocking said line to' currents of a signalling frequency or frequencies, an amplifier, a slow to release relay, said relay operating during transmission of non-signalling currents through said amplifier to disable and cause said blocking means to remain disabled during transmission of speech currents over said line, even though the speech frequenc component consists of currents of the signalling frequency or frequencies.
  • a line circuit over which speech currents are to be transmitted, andover which certain control frequencies are also transmitted a filter in the line circuit tuned to block the control frequencies from passing over the line, a device associated with the line and responsive to frequencies of current other than the control frequencies to render the filter in the line circuit ineffective.
  • said filter comprises an element of resistance material having a high negative coefiicient of resistance change with temperature, and means consisting of a heating coil in series with a second filter to render said first filter ineffective.
  • a line circuit over I which voice frequency signalling currents are transmitted incidental to the setting up of a connection over the line, means normally operafive to obstruct the passage over said line of all frequency currents, and means responsive to the transmission of non-signalling frequencies over the line for removing the obstruction.
  • a line circuit'over which voice frequency'signalling currents are transmitted during the setting up of a connection over the line means blocking said line to all frequenc currents, a control branch of said line circuit, a filter in said control branch, a device operating over said control branch in response to the transmission over the line circuit of currents of non-signalling frequencies for removing the blocking means to permit the transmission of all frequency currents over the line.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
US474905A 1942-04-28 1943-02-06 Telephone system Expired - Lifetime US2364685A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5664/42A GB557013A (en) 1942-04-28 1942-04-28 Improvements in or relating to telephone systems

Publications (1)

Publication Number Publication Date
US2364685A true US2364685A (en) 1944-12-12

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ID=9800312

Family Applications (1)

Application Number Title Priority Date Filing Date
US474905A Expired - Lifetime US2364685A (en) 1942-04-28 1943-02-06 Telephone system

Country Status (3)

Country Link
US (1) US2364685A (en, 2012)
BE (1) BE466455A (en, 2012)
GB (1) GB557013A (en, 2012)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3060275A (en) * 1958-11-07 1962-10-23 Bell Telephone Labor Inc Telephone system signaling
US3103558A (en) * 1959-09-24 1963-09-10 Int Standard Electric Corp ligotky
US3140356A (en) * 1959-06-23 1964-07-07 Siemens Ag Communication system employing frequency selection operations
US3201524A (en) * 1961-03-27 1965-08-17 Itt Multi-frequency tone signaling system
US3436487A (en) * 1965-09-14 1969-04-01 Bell Telephone Labor Inc Telephone signaling arrangement
US3610829A (en) * 1966-06-29 1971-10-05 Siemens Ag Transmission of pulse-coded information over telephone lines
US4726095A (en) * 1986-07-17 1988-02-23 Bissell Jr Norman L Bucket fish scaler

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3060275A (en) * 1958-11-07 1962-10-23 Bell Telephone Labor Inc Telephone system signaling
US3140356A (en) * 1959-06-23 1964-07-07 Siemens Ag Communication system employing frequency selection operations
US3103558A (en) * 1959-09-24 1963-09-10 Int Standard Electric Corp ligotky
US3201524A (en) * 1961-03-27 1965-08-17 Itt Multi-frequency tone signaling system
US3436487A (en) * 1965-09-14 1969-04-01 Bell Telephone Labor Inc Telephone signaling arrangement
US3610829A (en) * 1966-06-29 1971-10-05 Siemens Ag Transmission of pulse-coded information over telephone lines
US4726095A (en) * 1986-07-17 1988-02-23 Bissell Jr Norman L Bucket fish scaler

Also Published As

Publication number Publication date
GB557013A (en) 1943-11-01
BE466455A (en, 2012)

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