JPS57170656A - Multi-frequency signal receiver - Google Patents

Multi-frequency signal receiver

Info

Publication number
JPS57170656A
JPS57170656A JP56056741A JP5674181A JPS57170656A JP S57170656 A JPS57170656 A JP S57170656A JP 56056741 A JP56056741 A JP 56056741A JP 5674181 A JP5674181 A JP 5674181A JP S57170656 A JPS57170656 A JP S57170656A
Authority
JP
Japan
Prior art keywords
frequency signal
level
threshold
received signal
group filter
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.)
Pending
Application number
JP56056741A
Other languages
Japanese (ja)
Inventor
Kazunari Hirano
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.)
NEC Corp
Original Assignee
NEC Corp
Nippon Electric Co Ltd
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 NEC Corp, Nippon Electric Co Ltd filed Critical NEC Corp
Priority to JP56056741A priority Critical patent/JPS57170656A/en
Publication of JPS57170656A publication Critical patent/JPS57170656A/en
Pending 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
    • H04Q1/46—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies comprising means for distinguishing between a signalling current of predetermined frequency and a complex current containing that frequency, e.g. speech current

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)

Abstract

PURPOSE:To prevent signal distortion by detecting effectiveness of received signal as a multi-frequency signal and making the receiving level larger than echo level. CONSTITUTION:Received signal i added to a low group filter 2 and a high group filter 2'. Output of the low group filter 2 is led to low group discriminating circuits 5-8 through a variable threshold limiter 3 and output of high group filter 2' is led to high group discriminating circuits 9-12 through a variable threshold limiter 3'. When effectiveness of the received signal as a multi-frequency signal is detected by logical sum circuits 13, 14 and a logical product circuit 15, the threshold level of limiters 3, 3' is made larger than the echo level via a rectifier circuit 4. When the rear end of the multi-frequency signal is detected, a monostable circuit 16 is operated to maintain the threshold for a specified time. The threshold level is lowered after echo disappears.
JP56056741A 1981-04-14 1981-04-14 Multi-frequency signal receiver Pending JPS57170656A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP56056741A JPS57170656A (en) 1981-04-14 1981-04-14 Multi-frequency signal receiver

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP56056741A JPS57170656A (en) 1981-04-14 1981-04-14 Multi-frequency signal receiver

Publications (1)

Publication Number Publication Date
JPS57170656A true JPS57170656A (en) 1982-10-20

Family

ID=13035946

Family Applications (1)

Application Number Title Priority Date Filing Date
JP56056741A Pending JPS57170656A (en) 1981-04-14 1981-04-14 Multi-frequency signal receiver

Country Status (1)

Country Link
JP (1) JPS57170656A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985002509A1 (en) * 1983-12-02 1985-06-06 Telefonaktiebolaget Lm Ericsson Apparatus for correcting frequency-dependent attenuation of the transmitting medium in signal transmission

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985002509A1 (en) * 1983-12-02 1985-06-06 Telefonaktiebolaget Lm Ericsson Apparatus for correcting frequency-dependent attenuation of the transmitting medium in signal transmission

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