US2117843A - Frequency selective circuits - Google Patents

Frequency selective circuits Download PDF

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Publication number
US2117843A
US2117843A US113820A US11382036A US2117843A US 2117843 A US2117843 A US 2117843A US 113820 A US113820 A US 113820A US 11382036 A US11382036 A US 11382036A US 2117843 A US2117843 A US 2117843A
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US
United States
Prior art keywords
frequency
source
line
resistance
current
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
US113820A
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English (en)
Inventor
Charles W Green
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
Bell Telephone 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
Priority to BE424937D priority Critical patent/BE424937A/xx
Priority to NL49979D priority patent/NL49979C/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US113820A priority patent/US2117843A/en
Priority to FR830249D priority patent/FR830249A/fr
Priority to CH211212D priority patent/CH211212A/de
Application granted granted Critical
Publication of US2117843A publication Critical patent/US2117843A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J1/00—Frequency-division multiplex systems
    • H04J1/02—Details
    • H04J1/14—Arrangements providing for calling or supervisory signals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/04—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having negative temperature coefficient
    • 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

  • SIGNAL I I0 RECEIVER /4 Fl G. 2 sum:
  • This invention relates to frequency selective circuits such as may be employed in discriminating between signaling currents of diflerent frequencies.
  • One object of the invention is to increase the impedance of a tuned circuit to frequencies differing materially from the frequency to which the circuit is tuned while offering a substantially reduced impedance to current of the critical frequ cv- I
  • Another object is to maintain a frequency selec-- tive circuit of high impedance to the frequency to which it is resonant, unless the current of said frequency is applied longer than a definite time interval.
  • the invention is principally diversion from a transmission linefof a current of a single frequency or narrow band of frequencies. For example, in'voice frequency ringing over a telephone line, it is desirable to divert the voice frequency signal into its proper receiving circuit without introducing appreciable loss in the other frequency bands transmitted over the line.
  • the invention may comprise inshunt to a transmission line a condenser,
  • a resistance element such as a silver sulphide resistance having a high negative temperature eihcient of resistance, and the primary winding of a transformer, the transformer and the condenser being resonant at the frequency to be diverted,'for example, a ringing current of 1,000
  • the characteristics-01a silver sulphide resistor are such that it presents a high resistance when subjected to voltage below a cer- .tain critical value but as the voltage is increased, the temperature of the resistance is increased until a critical point is reached at which the resistance drops to a very low value.
  • the above described bridge circuit because of the impedance of the tuned circuit and because of the high resistance of the silver sulphide element for thev usual low voltages of speech currents near a receivingstation introduces a negligible loss at all frequencies at these low voltages.
  • the transmission line 5 may be traversed by speech frequencies or by a carrier wave modulated by the voice from a source such as source 6 to be received at a distant station by suitable receiver I which for carrier operation would include a suitable demodulator or detecting device.
  • a source 8 of signaling current In shunt to line 5 at one station is a source 8 of signaling current and a key 9 for connecting the source to the line.
  • Winding II and condenser ii are tuned for series resonance at the frequency of the source I.
  • the secondary winding 'II of the transformer leads to a suitable signal receiver ll.
  • the silver sul-- phideresistor i2 possesses a very high resistance and the shunt circuit ill, i2, therefore, introduces a negligible loss for all frequencies in the speech 40 or carrier bands provided the voltage across the silver sulphide resistor is below its critical value.
  • the bridge circuit II, II receives the signaling frequency from source I with full eiiiciency.
  • the silver sulphide unit employed in the above described tuned circuit should preferably be of such size and, thermal design that its temperature due to the received voltage from frequency source 8 does not reach the critical value-unless this voltage persists for an appreciable time such as 0.5 second. This will aid the signal receiver ll in discriminating against momentarily im-' and the tuning condenser may be placed in series with the secondary winding [3 instead of in series with the primary. winding II. This modification is shown him. 2 where a tuning condenser ll and a silver sulphide resistance ll are connected in series with the secondary winding If.
  • the transmission characteristics of the bridge circuit i8, I! 01' Fig. 2 are the same as those described above for Fig. 1.
  • a sourceof signaling current of a wide band offrequencies a second source of signaling current of a narrow band of frequencies, a line, means for impressing on said linesignaling currents from both of said s sources and a path bridged across said line comprising a condenser, the primary winding of a second source, said path being of high impedance to the signaling current from said first 2.
  • a line In a traon system, a line, a source of speech currents, a source of ringing current of a definite frequency, means for impressing currents from SMLSOHICGS upon said line, a receiving station whcze the current received over said line from said second source is of higher voltage than be emnloyed inplace 1 tthe-current received from said first source, and means at said receiving station for receiving current from said second source, said means comprising in shunt to said line the primary winding of a transformer and a resistance element having a high negative temperature coefiicient of resistance.
  • a line In a signal on system, a line, a source of signaling currents of a wide band of frequencies, a source of ringing current of a definite-frequency, means for impr currents from said sources upon said line, a receiving sta-.
  • said means including a nonlinear resistance, an inductance connected across said circuit in series with said resistance, and means responsive to the ringing current potential developed across the terminals of said inductance.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Signal Processing (AREA)
  • Telephonic Communication Services (AREA)
  • Devices For Supply Of Signal Current (AREA)
US113820A 1936-12-02 1936-12-02 Frequency selective circuits Expired - Lifetime US2117843A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE424937D BE424937A (en:Method) 1936-12-02
NL49979D NL49979C (en:Method) 1936-12-02
US113820A US2117843A (en) 1936-12-02 1936-12-02 Frequency selective circuits
FR830249D FR830249A (fr) 1936-12-02 1937-12-01 Circuits sélecteurs de fréquence
CH211212D CH211212A (de) 1936-12-02 1937-12-02 Anlage für Trägerfrequenztelephonie.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US113820A US2117843A (en) 1936-12-02 1936-12-02 Frequency selective circuits

Publications (1)

Publication Number Publication Date
US2117843A true US2117843A (en) 1938-05-17

Family

ID=22351700

Family Applications (1)

Application Number Title Priority Date Filing Date
US113820A Expired - Lifetime US2117843A (en) 1936-12-02 1936-12-02 Frequency selective circuits

Country Status (5)

Country Link
US (1) US2117843A (en:Method)
BE (1) BE424937A (en:Method)
CH (1) CH211212A (en:Method)
FR (1) FR830249A (en:Method)
NL (1) NL49979C (en:Method)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2694163A (en) * 1951-03-16 1954-11-09 Joseph G Sola Voltage sensitive apparatus
US2801290A (en) * 1951-09-17 1957-07-30 Telefunken Gmbh Calling signal responder arrangements

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2694163A (en) * 1951-03-16 1954-11-09 Joseph G Sola Voltage sensitive apparatus
US2801290A (en) * 1951-09-17 1957-07-30 Telefunken Gmbh Calling signal responder arrangements

Also Published As

Publication number Publication date
FR830249A (fr) 1938-07-25
NL49979C (en:Method)
CH211212A (de) 1940-08-31
BE424937A (en:Method)

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