GB798084A - Improvements relating to frequency dividing circuits - Google Patents

Improvements relating to frequency dividing circuits

Info

Publication number
GB798084A
GB798084A GB882254A GB882254A GB798084A GB 798084 A GB798084 A GB 798084A GB 882254 A GB882254 A GB 882254A GB 882254 A GB882254 A GB 882254A GB 798084 A GB798084 A GB 798084A
Authority
GB
United Kingdom
Prior art keywords
pulses
division ratio
frequency
switches
trigger
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
GB882254A
Inventor
Eric Lawrence Casling White
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.)
EMI Ltd
Electrical and Musical Industries Ltd
Original Assignee
EMI Ltd
Electrical and Musical Industries 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 EMI Ltd, Electrical and Musical Industries Ltd filed Critical EMI Ltd
Priority to GB882254A priority Critical patent/GB798084A/en
Publication of GB798084A publication Critical patent/GB798084A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K23/00—Pulse counters comprising counting chains; Frequency dividers comprising counting chains
    • H03K23/64—Pulse counters comprising counting chains; Frequency dividers comprising counting chains with a base or radix other than a power of two
    • H03K23/66—Pulse counters comprising counting chains; Frequency dividers comprising counting chains with a base or radix other than a power of two with a variable counting base, e.g. by presetting or by adding or suppressing pulses
    • H03K23/662—Pulse counters comprising counting chains; Frequency dividers comprising counting chains with a base or radix other than a power of two with a variable counting base, e.g. by presetting or by adding or suppressing pulses by adding or suppressing pulses
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K21/00—Details of pulse counters or frequency dividers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/04—Synchronising
    • H04N5/06—Generation of synchronising signals

Abstract

798,084. Electronic. counting-apparatus. ELECTRIC & MUSICAL INDUSTRIES, Ltd. March 28, 1955 [March 26, 1954], No. 8822/54. Class 106 (1). A frequency dividing circuit comprises a chain of binary counters, feedback connections enclosing different groups of counters and capable of feeding back signals in such manner as to increase or decrease the division ratio of the circuit and means for selectively disabling the connections so that the division ratio can be varied selectively in discrete steps. The frequency divider shown comprises series-connected binary counters BC1-BC9 input pulses being applied to BC1 through a gate G controlled by a trigger circuit T, e.g. of the Eccles- Jordan type. When the trigger is switched to the " 1 " condition by a pulse fed back from BC9 via diode D5, or, if switches S1-S4 are closed, from BC5, BC6, BC7 or BC8 via diode D1, D2, D3 or D4, it closes the gate so that the next input pulse is barred, this pulse resetting the trigger via delay means DM; the division ratio is thus increased by 1. Therefore, by selective operation of switches S1-S4 the division ratio can be varied between the limits 513 (2<SP>9</SP> + 1) and 543. For a colour television system, e.g. as described in Specification 798,083, [Group XL (b)], the divider produces, from input pulses having the chrominance subcarrier frequency, pulses of half the line frequency from counter BC9. The two outputs of BC9 may be combined as shown, by means including delay DM2, to obtain line frequency pulses; and double line frequency pulses for interlacing are obtained from BC7. The switches S1-S4 may be operated automatically by relays controlled e.g. in accordance with the mains and field frequencies. The feedback pulses, instead of inhibiting input pulses, may be injected into the divider as additional input pulses thereby reducing the division ratio.
GB882254A 1954-03-26 1954-03-26 Improvements relating to frequency dividing circuits Expired GB798084A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB882254A GB798084A (en) 1954-03-26 1954-03-26 Improvements relating to frequency dividing circuits

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB882254A GB798084A (en) 1954-03-26 1954-03-26 Improvements relating to frequency dividing circuits

Publications (1)

Publication Number Publication Date
GB798084A true GB798084A (en) 1958-07-16

Family

ID=9859889

Family Applications (1)

Application Number Title Priority Date Filing Date
GB882254A Expired GB798084A (en) 1954-03-26 1954-03-26 Improvements relating to frequency dividing circuits

Country Status (1)

Country Link
GB (1) GB798084A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2429530A1 (en) * 1978-06-19 1980-01-18 Sony Corp APPARATUS FOR READING CODED SIGNALS ON A VIDEO RECORDING MEDIUM
US4580282A (en) * 1981-11-25 1986-04-01 Plessey Overseas Limited Adjustable ratio divider

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2429530A1 (en) * 1978-06-19 1980-01-18 Sony Corp APPARATUS FOR READING CODED SIGNALS ON A VIDEO RECORDING MEDIUM
US4580282A (en) * 1981-11-25 1986-04-01 Plessey Overseas Limited Adjustable ratio divider

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