JPS55127755A - Digital tone signal detector - Google Patents

Digital tone signal detector

Info

Publication number
JPS55127755A
JPS55127755A JP3529879A JP3529879A JPS55127755A JP S55127755 A JPS55127755 A JP S55127755A JP 3529879 A JP3529879 A JP 3529879A JP 3529879 A JP3529879 A JP 3529879A JP S55127755 A JPS55127755 A JP S55127755A
Authority
JP
Japan
Prior art keywords
inputted
gate
circuit
output
waveform shaping
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
JP3529879A
Other languages
Japanese (ja)
Inventor
Yasuhiro Mori
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 JP3529879A priority Critical patent/JPS55127755A/en
Publication of JPS55127755A publication Critical patent/JPS55127755A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes

Landscapes

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

Abstract

PURPOSE:To make it possible to realize always normal detection operations without interference in tone detection even if the duty of a waveform shaping circuit is changed, by causing the output of the waveform shaping circuit to pass through a frequency dividing circuit to detect the frequency. CONSTITUTION:The tone signal is made into pulses by waveform shaping circuit 20, and the output is inputted to frequency dividing circuit 200 to generate complementary pulses, and one and the other of them are inputted to AND gate 202 and AND gate 203 respectively to control passage of clocks of clock generating circuit 201. Clocks passing through AND gates 202 and 203 are inputted to frequency detection circuits 204 and 205 respectively, and outputs of them are inputted to integtating circuit 207 through OR gate 206, and integration is started in response to the first output of OR gate 206, and a tone detection signal is outputted only when counting previously expected is satistied within a set time.
JP3529879A 1979-03-26 1979-03-26 Digital tone signal detector Pending JPS55127755A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP3529879A JPS55127755A (en) 1979-03-26 1979-03-26 Digital tone signal detector

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3529879A JPS55127755A (en) 1979-03-26 1979-03-26 Digital tone signal detector

Publications (1)

Publication Number Publication Date
JPS55127755A true JPS55127755A (en) 1980-10-02

Family

ID=12437862

Family Applications (1)

Application Number Title Priority Date Filing Date
JP3529879A Pending JPS55127755A (en) 1979-03-26 1979-03-26 Digital tone signal detector

Country Status (1)

Country Link
JP (1) JPS55127755A (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52133608A (en) * 1976-04-30 1977-11-09 Mitsubishi Electric Corp Frequency discriminating circuit

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52133608A (en) * 1976-04-30 1977-11-09 Mitsubishi Electric Corp Frequency discriminating circuit

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