JPS54128644A - Clock selection circuit - Google Patents

Clock selection circuit

Info

Publication number
JPS54128644A
JPS54128644A JP3722178A JP3722178A JPS54128644A JP S54128644 A JPS54128644 A JP S54128644A JP 3722178 A JP3722178 A JP 3722178A JP 3722178 A JP3722178 A JP 3722178A JP S54128644 A JPS54128644 A JP S54128644A
Authority
JP
Japan
Prior art keywords
clock
spare
existing
selection
detection circuits
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.)
Granted
Application number
JP3722178A
Other languages
Japanese (ja)
Other versions
JPS6148725B2 (en
Inventor
Yoshibumi Kato
Shikitoshi Doumori
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 JP3722178A priority Critical patent/JPS54128644A/en
Publication of JPS54128644A publication Critical patent/JPS54128644A/en
Publication of JPS6148725B2 publication Critical patent/JPS6148725B2/ja
Granted legal-status Critical Current

Links

Landscapes

  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

PURPOSE: To prevent the phase variation at selection, by taking the time constant of monostable multivibrator detecting the open clock as within the specified condition.
CONSTITUTION: The existing and spare clock of bipolar type fed from rhe existing and spare digital clock supply units 41 and 42 are converted into the unipolar signal at the bipolar unipolar conversion circuits 6 and 7. The converted clock is given to the open detection circuits 80 and 90. The selection circuit 10 is controlled with the open detection circuits 80 and 90 and either of them is selected. The clock is inputted to the tuning circuit 11 and the output is given to the digital units 1,2. As the open detection circuits 80,90, the monostable multivibrator having edge trigger type so that the time constant Yd satisfies the equation -(2), is used. Where t is a half period of the clock, and n is an integer. As a result, the drive pulse to the circuit 11 when the unit is changed over from existing to spare, is on the same time series, and the phase variation is prevented for selection.
COPYRIGHT: (C)1979,JPO&Japio
JP3722178A 1978-03-29 1978-03-29 Clock selection circuit Granted JPS54128644A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP3722178A JPS54128644A (en) 1978-03-29 1978-03-29 Clock selection circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3722178A JPS54128644A (en) 1978-03-29 1978-03-29 Clock selection circuit

Publications (2)

Publication Number Publication Date
JPS54128644A true JPS54128644A (en) 1979-10-05
JPS6148725B2 JPS6148725B2 (en) 1986-10-25

Family

ID=12491525

Family Applications (1)

Application Number Title Priority Date Filing Date
JP3722178A Granted JPS54128644A (en) 1978-03-29 1978-03-29 Clock selection circuit

Country Status (1)

Country Link
JP (1) JPS54128644A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63191434A (en) * 1987-02-04 1988-08-08 Nippon Telegr & Teleph Corp <Ntt> Clock circuit
JPH03165134A (en) * 1989-11-24 1991-07-17 Nec Corp Clock selection switching system
US5287010A (en) * 1989-12-27 1994-02-15 Masao Hagiwara Device for preventing erroneous operation when the clock is interrupted in a controller

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63191434A (en) * 1987-02-04 1988-08-08 Nippon Telegr & Teleph Corp <Ntt> Clock circuit
JPH03165134A (en) * 1989-11-24 1991-07-17 Nec Corp Clock selection switching system
US5287010A (en) * 1989-12-27 1994-02-15 Masao Hagiwara Device for preventing erroneous operation when the clock is interrupted in a controller

Also Published As

Publication number Publication date
JPS6148725B2 (en) 1986-10-25

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