JPS5772451A - Frequency detection system - Google Patents

Frequency detection system

Info

Publication number
JPS5772451A
JPS5772451A JP55147541A JP14754180A JPS5772451A JP S5772451 A JPS5772451 A JP S5772451A JP 55147541 A JP55147541 A JP 55147541A JP 14754180 A JP14754180 A JP 14754180A JP S5772451 A JPS5772451 A JP S5772451A
Authority
JP
Japan
Prior art keywords
signal
extracted
pass filter
output
specific 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.)
Pending
Application number
JP55147541A
Other languages
Japanese (ja)
Inventor
Yasushi Takeuchi
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.)
Hitachi Ltd
Original Assignee
Hitachi 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 Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP55147541A priority Critical patent/JPS5772451A/en
Publication of JPS5772451A publication Critical patent/JPS5772451A/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
    • H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
    • H04L27/14—Demodulator circuits; Receiver circuits
    • H04L27/156—Demodulator circuits; Receiver circuits with demodulation using temporal properties of the received signal, e.g. detecting pulse width
    • H04L27/1563—Demodulator circuits; Receiver circuits with demodulation using temporal properties of the received signal, e.g. detecting pulse width using transition or level detection

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 hold down the variation of a detection time within a constant range, by detecting specific frequency components, which are extracted from a variable frequency signal, by a specific constant set to a low value. CONSTITUTION:A variable frequency signal A is obtained from an FM receiver 1, and specific frequency components are extracted from this signal by a band pass filter 2. An extracted signal B passes through a rectifier 3 and a low pass filter 7 and is compared with a maximum disturbance level TTH due to a noise, distortion, etc. by a comparator 5. The time constant of the low pass filter 7 is set to a considerable low value. An output E of the comparator 5 is delayed by a delay or count means 8, and an output F is outputted as a specific frequency output.
JP55147541A 1980-10-23 1980-10-23 Frequency detection system Pending JPS5772451A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP55147541A JPS5772451A (en) 1980-10-23 1980-10-23 Frequency detection system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP55147541A JPS5772451A (en) 1980-10-23 1980-10-23 Frequency detection system

Publications (1)

Publication Number Publication Date
JPS5772451A true JPS5772451A (en) 1982-05-06

Family

ID=15432646

Family Applications (1)

Application Number Title Priority Date Filing Date
JP55147541A Pending JPS5772451A (en) 1980-10-23 1980-10-23 Frequency detection system

Country Status (1)

Country Link
JP (1) JPS5772451A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60236550A (en) * 1984-05-10 1985-11-25 Sharp Corp Frequency demodulator

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60236550A (en) * 1984-05-10 1985-11-25 Sharp Corp Frequency demodulator

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