GB831713A - Improvements in or relating to voice frequency signal receivers - Google Patents

Improvements in or relating to voice frequency signal receivers

Info

Publication number
GB831713A
GB831713A GB24845/58A GB2484558A GB831713A GB 831713 A GB831713 A GB 831713A GB 24845/58 A GB24845/58 A GB 24845/58A GB 2484558 A GB2484558 A GB 2484558A GB 831713 A GB831713 A GB 831713A
Authority
GB
United Kingdom
Prior art keywords
harmonic
circuit
signal
frequency
tuned
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
Application number
GB24845/58A
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.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
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 Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Publication of GB831713A publication Critical patent/GB831713A/en
Expired legal-status Critical Current

Links

Classifications

    • 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
    • H04Q1/45—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using multi-frequency signalling
    • H04Q1/453—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using multi-frequency signalling in which m-out-of-n signalling frequencies are transmitted
    • 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
    • H04Q1/442—Signalling arrangements; Manipulation of signalling currents using alternate current with out-of-voice band signalling frequencies
    • H04Q1/4423—Signalling arrangements; Manipulation of signalling currents using alternate current with out-of-voice band signalling frequencies using one signalling frequency
    • 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

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Reduction Or Emphasis Of Bandwidth Of Signals (AREA)
  • Interface Circuits In Exchanges (AREA)

Abstract

831,713. Voice immunity circuits. STANDARD TELEPHONES & CABLES Ltd. Aug. 1, 1958 [Aug. 6, 1957], No. 24845/58. Addition to 704,922. Class 40 (4). A signal of predetermined frequency incoming to a V.F. receiver is symmetrically voltage limited to generate the third harmonic which is applied to a circuit tuned to this harmonic over an amplifier having a symmetrical voltage limiter in a negative feed-back circuit so as to provide a threshold for signals applied to the tuned circuit. With a signal frequency of 2280 c.p.s. there is a rick that a voice frequency of 1368 c.p.s. will interfere with its fifth harmonic which coincides with the third harmonic of 2280 c.p.s. The relative amplitude of each of these harmonics produced by symmetrical voltage limiting to a small value E is 4E/3# to 4E/5# so that if the threshold of the negative feed-back amplifier lies between these limits the fifth harmonic will be suppressed. As shown in the Figure the input signal over T1, amplifier V1, and T2, is limited symmetrically by diodes W1, W2, tied to the ends of resistors R4, R5. The third harmonic of the input signal is extracted by the Œ60 c.p.s. band-pass filter F1 and applied to amplifier V2 in the cathode circuit of which is the non-linear impedance presented by transformer T4 and the voltage limiting diodes W3, W4, in its secondary circuit. The cathode circuit of V2 is tuned to a frequency between the fundamental and third harmonic and the anode circuit is tuned to the third harmonic and is connected to energize relay S. When the input to V2 reaches a critical value, diodes W3, W4, conduct and drop the cathode impedance of V2 to R11 to excite the anode circuit. The limiting voltages connected to W3 and W4 are the same as are connected to W1 and W2 which it is shown makes the threshold voltage dependent solely on the turns ratio of T4. It still remains possible for an input signal departing slightly in frequency from the control signal but of sufficiently large amplitude to negotiate filter F1 to operate relay S. To avoid this a backbiased rectifier W7 is forwardly biased to conduct over capacitor C7 whenever an abnormally large signal appears from T2. A voltage from R15 is then smoothed and applied as back bias to V2 to block the signal. An additional untuned transformer may be connected serially with T2 to provide a speech channel.
GB24845/58A 1951-04-27 1958-08-01 Improvements in or relating to voice frequency signal receivers Expired GB831713A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
NL160821 1951-04-27
NL219653 1957-08-06
DES55307A DE1046116B (en) 1951-04-27 1957-09-27 Circuit arrangement for receiving audio frequency signals in telecommunications, in particular telephone systems

Publications (1)

Publication Number Publication Date
GB831713A true GB831713A (en) 1960-03-30

Family

ID=27212615

Family Applications (1)

Application Number Title Priority Date Filing Date
GB24845/58A Expired GB831713A (en) 1951-04-27 1958-08-01 Improvements in or relating to voice frequency signal receivers

Country Status (2)

Country Link
DE (1) DE1046116B (en)
GB (1) GB831713A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3103558A (en) * 1959-09-24 1963-09-10 Int Standard Electric Corp ligotky

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE745228C (en) * 1939-07-28 1944-03-01 Siemens Ag Electrical signal receiver
DE856164C (en) * 1943-10-29 1952-11-20 Siemens Ag Electrical signal receiver
DE899373C (en) * 1952-04-22 1953-12-10 Telefonbau & Normalzeit Gmbh Circuit arrangement for advancing charge displays assigned to the subscriber lines

Also Published As

Publication number Publication date
DE1046116B (en) 1958-12-11

Similar Documents

Publication Publication Date Title
US2173925A (en) Noise reduction circuits
US2247085A (en) Amplifier
US2166995A (en) Noise reduction system
GB1044003A (en) Improvements relating to sound recording and transmission systems
GB831713A (en) Improvements in or relating to voice frequency signal receivers
US2273640A (en) Superheterodyne receiver
US2283415A (en) Signaling system
US2420249A (en) Amplitude modulation reducing circuit
US2540813A (en) Angle modulation demodulator
US2125953A (en) Receiver of telephonic or telegraphic signals
US2344699A (en) Amplitude modulation limiter circuit
US2883480A (en) Limiting amplifier
GB668498A (en) Improvements in or relating to superheterodyne radio-receivers
US3895310A (en) Automatic gain control circuit
GB656189A (en) Improvements in or relating to receiving circuits for telephony
US2094625A (en) Selective radio receiving system
US3215940A (en) Volume compression circuits
US2921196A (en) Transistor regenerative detector circuit
US2644084A (en) Discriminator improvement to reduce audio-frequency noise
US2952816A (en) Limiting amplifier
US2277040A (en) Noise limiting circuit
US2531505A (en) Noise suppression means for communication receiving apparatus
US2125723A (en) Interference elimination
GB713433A (en) Improvements in or relating to magnetic amplifiers
GB796082A (en) Improved a.m. or f.m. radio receiver detector circuit