Frequency comparator

Claim 2

Frequency comparing apparatus comprising first and second oscillators, means responsive to said first oscillator for generating a first train of pulses, means responsive to the second oscillator for generating second and third trains of pulses, pulses of one of said second and third trains being separated with respect to pulses of the other so as to provide an absence of both for an interval approximately equal to the width of pulses of said first train, and relative phase means responsive to said trains of pulses for indicating occurrence of a pulse of said first train in the interval between a pulse of said second train and a pulse of said third train.

Claim 3

Frequency comparing apparatus comprising first and second oscillators, means responsive to said first oscillator for generating a first train of pulses, means responsive to the second oscillator for generating second and third trains of pulses, pulses of one of said second and third trains being separated with respect to pulses of the other by an amount approximately equal to the width of pulses of said first train, relative phase means responsive to said trains of pulses for indicating occurrence of a pulse of said first train in the interval between a pulse of said second train and a pulse of said third train, means for detecting the sense of the relative frequency of said oscillators, and means responsive to said relative phase means for enabling said sense detecting means.

Claim 4

Frequency comparing apparatus comprising first and second oscillators, means responsive to said first oscillator for generating a first train of pulses, means responsive to the second oscillator for generating second and third trains of pulses, pulses of one of said second and third trains being separated with respect to pulses of the other by an amount approximately equal to the width of pulses of said first train, relative phase means responsive to said trains of pulses for indicating occurrence of a pulse of said first train in the interval between a pulse of said second train and a pulse of said third train, means for detecting the sense of the relative frequency of said oscillators, and means responsive to said relative phase means for enabling said sense detecting means.

Claim 5

In combination a first periodic generator, a second periodic generator, means responsive to said first generator for generating a series of pairs of pulses of which the leading edge of one follows the trailing edge of the other by a gunsight interval, means responsive to said second generator for generating a series of sighting pulses having a duration not substantially greater than said gunsight interval, and means responsive to said pulses for indicating occurrence of a sighting pulse in one of said gunsight intervals, to thereby signal occurrence of a precise phase relation between said periodic generators.

Claim 6

In combination a first periodic generator, a second periodic generator, means responsive to said first generator for generating a series of pairs of pulses of which the leading edge of one follows the trailing edge of the other by a gunsight interval, means responsive to said second generator for generating a series of sighting pulses having a duration not substantially greater than said gunsight interval, and means responsive to said pulses for indicating occurrence of a sighting pulse in one of said gunsight intervals, to thereby signal occurrence of a precise phase relation between said periodic generators.

Claim 7

The apparatus set forth in claim 3 wherein one pulse of each pair of said series of pairs and pulses of said sighting pulses comprise first and second signals that occur in consecutive alternation at said phase relation between said periodic generators, and means for signalling occurrence of one of said signals out of said consecutive alternation.

Claim 8

The apparatus of claim 4 including means for signalling which of said first and second signals first occurs out of said alternation.

Claim 9

In combination a first periodic generator, a second periodic generator, means responsive to said first generator for generating a series of pairs of pulses separated from each other by a gunsight interval, means responsive to said second generator for generating a series of sighting pulses having a duration not substantially greater than said gunsight interval, means responsive to said pulses for indicating occurrence of a sighting pulse in one of said gunsight intervals, to thereby signal occurrence of a precise phase relation between said periodic generators, means for initiating a measurement interval upon said occurrence, and means for terminating said measurement interval when said sighting pulse moves out of said gunsight interval.

Claim 10

In combination a first periodic generator, a second periodic generator, means responsive to said first generator for generating a series of pairs of pulses separated from each other by a gunsight interval, means responsive to said second generator for generating a series of sighting pulses having a duration not substantially greater than said gunsight interval, means responsive to said pulses for indicating occurrence of a sighting pulse in one of said gunsight intervals, to thereby signal occurrence of a precise phase relation between said periodic generators, means for initiating a measurement interval upon said occurrence, and means for terminating said measurement interval when said sighting pulse moves out of said gunsight interval.

Claim 11

In combination a first periodic generator, a second periodic generator, means responsive to said first generator for generating a series of pairs of pulses separated from each other by a gunsight interval, means responsive to said second generator for generating a series of sighting pulses having a duration not substantially greater than said gunsight interval, means responsive to said pulses for indicating occurrence of a sighting pulse in one of said gunsight intervals, to thereby signal occurrence of a precise phase relation between said periodic generators, means for indicating overlap of a sighting pulse with one of the pulses of a pair of said series of pulse pairs, and means responsive to said overlap indicating means for initiating another search for occurrence of said sighting pulse in one of said gunsight intervals.

Claim 12

In combination a first periodic generator, a second periodic generator, means responsive to said first generator for generating a series of pairs of pulses separated from each other by a gunsight interval, means responsive to said second generator for generating a series of sighting pulses having a duration not substantially greater than said gunsight interval, means responsive to said pulses for indicating occurrence of a sighting pulse in one of said gunsight intervals, to thereby signal occurrence of a precise phase relation between said periodic generators, means for indicating overlap of a sighting pulse with one of the pulses of a pair of said series of pulse pairs, and means responsive to said overlap indicating means for initiating another search for occurrence of said sighting pulse in one of said gunsight intervals.

Claim 13

The structure of claim 7 including means for indicating occurrence of a sighting pulse between successive pairs of said series of pairs, and means for initiating a new search upon said last mentioned occurrence.

Claim 14

In combination a first periodic generator, a second periodic generator, means responsive to said first generator for generating a series of pairs of pulses separated from each other by a gunsight interval means responsive to said second generator for generating a series of sighting pulses having a duration not substantially greater than said gunsight interval, means responsive to said pulses for indicating occurrence of a sighting pulse in one of said gunsight intervals, to thereby signal occurrence of a precise phase relation between said periodic generators, and relative frequency sense detecting means for selecting one of said periodic generators according to whether the leading or trailing edge of the sighting pulse overlaps respectively the trailing or leading edge of a pulse of said pair after occurrence of said precise phase relation.

Claim 15

In combination a first periodic generator, a second periodic generator, means responsive to said first generator for generating a series of pairs of pulses separated from each other by a gunsight interval means responsive to said second generator for generating a series of sighting pulses having a duration not substantially greater than said gunsight interval, means responsive to said pulses for indicating occurrence of a sighting pulse in one of said gunsight intervals, to thereby signal occurrence of a precise phase relation between said periodic generators, and relative frequency sense detecting means for selecting one of said periodic generators according to whether the leading or trailing edge of the sighting pulse overlaps respectively the trailing or leading edge of a pulse of said pair after occurrence of said precise phase relation.

Claim 16

Timing apparatus comprising first and second oscillators having nominally equal frequencies, means for comparing the frequencies of said oscillators, means for selecting the oscillator having the higher frequency. said means for comparing frequencies of said oscillators comprising means for generating first and second end-of-measurement signals respectively indicating one or the other of said oscillators is determined to be slow, said apparatus further including a timer for generating a predetermined time interval, first and second interval comparators, each having a first input from said timer, and means responsive to respective ones of said end-of-measurement signals for enabling the first and second comparators and responsive to the occurrence of each of said end-of-measurement signals for initiating operation of the timer, whereby one or the other of said comparators will provide an output when the interval between successive occurrences of said end-of-measurement signals is smaller than the time interval generated by the timer.

Claim 17

Timing apparatus comprising first and second oscillators having nominally equal frequencies, means for comparing the frequencies of said oscillators, means for selecting the oscillator having the higher frequency. said means for comparing frequencies of said oscillators comprising means for generating first and second end-of-measurement signals respectively indicating one or the other of said oscillators is determined to be slow, said apparatus further including a timer for generating a predetermined time interval, first and second interval comparators, each having a first input from said timer, and means responsive to respective ones of said end-of-measurement signals for enabling the first and second comparators and responsive to the occurrence of each of said end-of-measurement signals for initiating operation of the timer, whereby one or the other of said comparators will provide an output when the interval between successive occurrences of said end-of-measurement signals is smaller than the time interval generated by the timer.

Claim 20

Timing apparatus comprising a first clock generator, a second clock generator, a reference interval generator responsive to the first clock generator for producing a series of pairs of reference interval pulses separated from each other by a reference interval, a sighting pulse generator responsive to the second clock generator for generating a sighting pulse having a width not substantially greater than said reference interval, relative phase detecting means rEsponsive to said reference interval and sighting pulse generators for detecting the occurrence of one of said sighting pulses within one of said reference intervals, relative frequency sense detecting means responsive to said relative phase detector and to said reference interval and sighting pulse generators for signalling the end of a measurement interval upon occurrence of one of the sighting pulses out of alternation with one of the pulses of a pair of reference interval pulses, and a clock switch responsive to said relative frequency sense detecting means and to said first and second clock generators for providing an output from the faster of said clock generators as determined by the relative frequency sense detector.

Claim 21

Timing apparatus comprising a first clock generator, a second clock generator, a reference interval generator responsive to the first clock generator for producing a series of pairs of reference interval pulses separated from each other by a reference interval, a sighting pulse generator responsive to the second clock generator for generating a sighting pulse having a width not substantially greater than said reference interval, relative phase detecting means rEsponsive to said reference interval and sighting pulse generators for detecting the occurrence of one of said sighting pulses within one of said reference intervals, relative frequency sense detecting means responsive to said relative phase detector and to said reference interval and sighting pulse generators for signalling the end of a measurement interval upon occurrence of one of the sighting pulses out of alternation with one of the pulses of a pair of reference interval pulses, and a clock switch responsive to said relative frequency sense detecting means and to said first and second clock generators for providing an output from the faster of said clock generators as determined by the relative frequency sense detector.

Claim 22

The timing apparatus of claim 12 including a slow frequency monitor responsive to said relative frequency sense detector and to the output of said clock switch for providing an alarm when the frequency of one of said clock generators is below a predetermined tolerance value.

Claim 23

The timing apparatus of claim 13 including a plurality of bad clock detectors for indicating the absence of a clock pulse from one of the clock generators during the occurrence of a predetermined number of consecutive pulses from the other of the clock generators.

Claim 24

The apparatus of claim 12 wherein said relative phase detecting means comprises sequence detecting means for detecting the occurrence in a consecutive sequence of a first one of the pulses of a pair of reference interval pulses, a sighting pulse, and the other one of the pair of reference interval pulses.

Claim 25

The timing apparatus of claim 15 wherein said relative phase detecting means includes means for disabling said sequence detecting means upon occurrence of predetermined improper conditions.

Claim 26

The timing apparatus of claim 16 wherein said disabling means includes means responsive to overlap of a portion of said sighting pulse with a portion of one of the pulses of a pair of reference interval pulses, and means for disabling the sequence detecting means upon occurrence of the second pulse of a pair of said pairs of pulses prior to occurrence of a sighting pulse during any sequence detection.

Claim 27

The timing apparatus of claim 16 wherein said means for disabling said sequence detecting means comprises means responsive to said relative frequency sense detecting means for clearing said relative phase detecting means to enable search for another sequence.

Claim 28

The timing apparatus of claim 18 wherein said relative frequency sense detecting means comprises a flip-flop having toggling inputs from said sighting pulses and from one pulse of each pair of said reference pulses, means for indicating coincidence of the respective states of said flip-flop with respective ones of said toggling input pulses, and means responsive to either one of said coincidences for clearing said sequence detector thereby to indicate termination of a measurement interval and permit the search for a new sequence.

Claim 29

Apparatus for comparing frequency of first and second oscillators comprising reference interval generating means responsive to said first oscillator for generating a series of pulse pairs with the pulses of each pair separated from each other by a reference interval and successive pairs of pulses separated from each other by a second interval, means responsive to the second oscillator for generating a train of sighting pulses, relative phase detector means comprising first, second, and third flip-flops each having a trigger input, a direct reset input, a set input, a reset input, and an output, means for connecting the first pulse of each of said pairs to the trigger input of the first flip-flop, means for connecting the output of the first flip-flop to the set input of the second flip-flop and connecting the sighting pulses to the trigger input of the second flip-flop, means for connecting the output of the second flip-flop to the set input of the third flip-flop and means for connecting the second pulse of each pair to the trigger input of the third flip-flop, a clear flip-flop having an output connected to the direct reset inputs of each of said first, second, and third flip-flops, and having trigger set and reset inputs, a first coincidence gate (64) having a first input representing coincidence of a sighting pulse with either pulse of a pair of said pairs of pulses, having a second input indicative of occurrence of the second pulse of a pair of said pairs of pulses in coincidence with the reset condition of said second flip-flop, a second end-of-measurement gate (66), said first gate having a third input from said end-of-measurement gate, a third fast clear coincidence gate (68) having a first input from the false output of said third flip-flop, having a second input from the output of said first coincidence gate (64), and having an output connected to the direct reset inputs of said first, second, and third flip-flops, a fourth inhibit coincidence gate (70) having inputs from the false outputs of each of said first, second, and third flip-flops and having an output inverted to the reset input of said clear flip-flop, said trigger input of said clear flip-flop being connected to the output of said first coincidence gate (64), relative frequency sense detecting means comprising a fifth flip-flop having set and reset inputs, a direct reset input, a trigger input, and true and false outputs, a fifth coincidence gating means (74, 78, 80, 82) for providing to the reset input of the fifth flip-flop a delayed signal representing coincidence of the sighting pulse and the true output of said third flip-flop, and for providing to the set input of the fifth flip-flop a signal representing coincidence of the true output of the said third flip-flop and one pulse of a pair of said pulses, means (84) for causing said fifth flip-flop to be toggled whenever either said sighting pulse or said one of said pulses of a pair occurs in coincidence with a true output of said third flip-flop, a sixth coincidence gate (85) for indicating coincidence of a false output of the fifth flip-flop, a true output of the third flip-flop, and a sighting pulse, to produce a signal p indicating said second oscillator to be faster than said first oscillator, a seventh coincidence gate (86) for indicating coincidence of true outputs of the third and fifth flip-flops and said one of said pulses of a pair to produce a signal q indicating said first oscillator to be faster than said second oscillator, an OR gate (92) for indicating occurrence of either of said signals p or q, and means responsive to said OR gate (92) for providing an input to said end-of-measurement gate (66).

Claim 30

Apparatus for comparing frequency of first and second oscillators comprising reference interval generating means responsive to said first oscillator for generating a series of pulse pairs with the pulses of each pair separated from each other by a reference interval and successive pairs of pulses separated from each other by a second interval, means responsive to the second oscillator for generating a train of sighting pulses, relative phase detector means comprising first, second, and third flip-flops each having a trigger input, a direct reset input, a set input, a reset input, and an output, means for connecting the first pulse of each of said pairs to the trigger input of the first flip-flop, means for connecting the output of the first flip-flop to the set input of the second flip-flop and connecting the sighting pulses to the trigger input of the second flip-flop, means for connecting the output of the second flip-flop to the set input of the third flip-flop and means for connecting the second pulse of each pair to the trigger input of the third flip-flop, a clear flip-flop having an output connected to the direct reset inputs of each of said first, second, and third flip-flops, and having trigger set and reset inputs, a first coincidence gate (64) having a first input representing coincidence of a sighting pulse with either pulse of a pair of said pairs of pulses, having a second input indicative of occurrence of the second pulse of a pair of said pairs of pulses in coincidence with the reset condition of said second flip-flop, a second end-of-measurement gate (66), said first gate having a third input from said end-of-measurement gate, a third fast clear coincidence gate (68) having a first input from the false output of said third flip-flop, having a second input from the output of said first coincidence gate (64), and having an output connected to the direct reset inputs of said first, second, and third flip-flops, a fourth inhibit coincidence gate (70) having inputs from the false outputs of each of said first, second, and third flip-flops and having an output inverted to the reset input of said clear flip-flop, said trigger input of said clear flip-flop being connected to the output of said first coincidence gate (64), relative frequency sense detecting means comprising a fifth flip-flop having set and reset inputs, a direct reset input, a trigger input, and true and false outputs, a fifth coincidence gating means (74, 78, 80, 82) for providing to the reset input of the fifth flip-flop a delayed signal representing coincidence of the sighting pulse and the true output of said third flip-flop, and for providing to the set input of the fifth flip-flop a signal representing coincidence of the true output of the said third flip-flop and one pulse of a pair of said pulses, means (84) for causing said fifth flip-flop to be toggled whenever either said sighting pulse or said one of said pulses of a pair occurs in coincidence with a true output of said third flip-flop, a sixth coincidence gate (85) for indicating coincidence of a false output of the fifth flip-flop, a true output of the third flip-flop, and a sighting pulse, to produce a signal p indicating said second oscillator to be faster than said first oscillator, a seventh coincidence gate (86) for indicating coincidence of true outputs of the third and fifth flip-flops and said one of said pulses of a pair to produce a signal q indicating said first oscillator to be faster than said second oscillator, an OR gate (92) for indicating occurrence of either of said signals p or q, and means responsive to said OR gate (92) for providing an input to said end-of-measurement gate (66).

Claim 31

The apparatus set forth in claim 20 including a memory flip-flop having set and reset inputs, direct set and direct reset inputs, a trigger input, and true and false outputs, means for providing said signal p from said sixth gate (85) to the reset input of said memory flip-flop, means for providing said output q of said seventh gate (86) to the set input of said memory flip-flop, means responsive to either said p or said q signal for providing a trigger input to said memory flip-flop, an eighth coincidence gate (94) having a first input from the true output of said memory flip-flop and having a second input from one of said oscillators, a ninth coincidence gate (96) having a first input from the false output of said memory flip-flop and having a second input from the other of said oscillators, and means for providing at the output of said apparatus the output of one of said eighth (94) or ninth (96) gates.

Claim 32

The apparatus as set forth in claim 21 including a first bad clock detector for indicating failure of one of said oscillators, a second bad clock detector for indicating failure of the other of said oscillators, means responsive to said first bad clock detector for providing an input to the direct set input of said memory flip-flop, and means responsive to the second bad clock detector for providing an input to the direct reset input of said memory flip-flop.

Claim 33

Apparatus for comparing frequencies of first and second pulse trains comprising means for initiating a measurement interval when pulses of said trains occur in a unique relation of consecutive alternation, means for thereafter terminating said measurement interval when pulses of said trains occur out of such consecutive alternation, and means for indicating the time between successive occurrences of said measurement interval to thereby indicate the magnitude of the difference in frequency between said trains.

Claim 34

Apparatus for comparing frequencies of first and second pulse trains comprising means for initiating a measurement interval when pulses of said trains occur in a unique relation of consecutive alternation, means for thereafter terminating said measurement interval when pulses of said trains occur out of such consecutive alternation, and means for indicating the time between successive occurrences of said measurement interval to thereby indicate the magnitude of the difference in frequency between said trains.

Claim 35

The apparatus of claim 23 including means for detecting which one of said trains includes a pulse that first occurs out of such consecutive alternation, to thereby detect which train is of higher frequency.

Claim 36

The apparatus of claim 24 including means for measuring the time interval between the detection of said first mentioned means and the detection of said second mentioned means.

Claim 37

The apparatus of claim 24 wherein said first train comprises a series of pairs of pulses and wherein said first mentioned means for detecting comprises sequence detecting means for signalling occurrence of a pulse of said second train between pulses of a pair of pulses of said first train.

Claim 38

Timing apparatus comprising first and second oscillators having nominally equal frequencies, means for comparing the frequencies of said oscillators, said means comprising means for signalling occurrence of a unique phase relation between the signals produced from said oscillators and means for signalling a change in said unique phase relation, said last mentioned means including means for indicating which of said oscillators has the higher frequency, output means, and selector means responsive to said frequency comparing means for feeding to said output means the signal produced by that one of said first and second oscillators that is indicated to have the higher frequency.

Claim 39

Timing apparatus comprising first and second oscillators having nominally equal frequencies, means for comparing the frequencies of said oscillators, said means comprising means for signalling occurrence of a unique phase relation between the signals produced from said oscillators and means for signalling a change in said unique phase relation, said last mentioned means including means for indicating which of said oscillators has the higher frequency, output means, and selector means responsive to said frequency comparing means for feeding to said output means the signal produced by that one of said first and second oscillators that is indicated to have the higher frequency.

Claim 40

Timing apparatus comprising first and second oscillators having nominally equal frequencies, means for comparing the frequencies of said oscillators, and means for selecting the oscillator having the higher frequency, said comparing means comprising means responsive to one of said oscillators for generating pairs of gunsight pulses, with the pulses of each pair separated from each other by a reference interval, means responsive to the other of said oscillators for generating a train of sighting pulses, relative phase detecting means for indicating occurrence of one of said sighting pulses within one of said reference intervals, and means responsive to said relative phase detecting means for indicating the sense of the frequency difference between said oscillators, said oscillator selecting means comprising a clock switch having an input from both of said oscillators, and means responsive to said sense indicating means for operating said clock switch to select one of said oscillators.

Claim 41

Timing apparatus comprising first and second oscillators having nominally equal frequencies, means for comparing the frequencies of said oscillators, and means for selecting the oscillator having the higher frequency, said comparing means comprising means responsive to one of said oscillators for generating pairs of gunsight pulses, with the pulses of each pair separated from each other by a reference interval, means responsive to the other of said oscillators for generating a train of sighting pulses, relative phase detecting means for indicating occurrence of one of said sighting pulses within one of said reference intervals, and means responsive to said relative phase detecting means for indicating the sense of the frequency difference between said oscillators, said oscillator selecting means comprising a clock switch having an input from both of said oscillators, and means responsive to said sense indicating means for operating said clock switch to select one of said oscillators.

Claim 42

The apparatus of claim 27 including means for measuring the difference in frequency between said oscillators, and means for signalling a frequency difference greater than a predetermined magnitude.

Claim 43

The apparatus of claim 29 wherein said means for comparing said oscillators comprises means for indicating a selected relative phase point of said oscillators, means for generating a predetermined time interval, and means for comparing said time interval with the interval between successive occurrences of said relative phase point.