Digital frequency lock generator

Claim 2

A pulse-train generator having an output whose frequency is automatically locked to the frequency of its input pulse train comprising, in combination: frequency-comparison means to which the input and output pulse trains are fed for measuring the time interval between each input pulse and the next succeeding output pulse and for comparing every two successive measurements to determine which is larger, the first measurement being called the A measurement and the second the B measurement; frequency-changing means to which the output of said comparison means is fed for generating a frequency-command signal corresponding to a pulse-train frequency, the frequency being increased or decreased in accordance with the determination of whether the B measurement is greater than the A measurement or vice versa; and free-running, pulse-train generating means to which the output of said frequency-changing means is fed for generating a train of output pulses, the frequency of said pulse train being determined by the input command signal to said pulse-train generating means.

Claim 3

A pulse-train generator as in claim 1, wherein said frequency-comparison means includes an input-output counter, a pair of store registers called an A-store register and a B-store register and a comparator, said counter being fed the input and output pulse trains and measuring the time interval between each input pulse and the next succeeding output pulse, said A-store register storing the first time-interval measurement and said B-store register storing the next time-interval measurement, and said comparator being fed the outputs of said store registers and comparing them to determine whether the A-store measurement is greater than the B-store measurement, or vice versa.

Claim 4

A pulse-train generator as in claim 1, wherein said frequency-changing means comprises a forward-reverse counter receiving a signal at its reverse input terminal from said frequency-comparison means if said A-measurement is greater than said B-measurement and at its forward terminal if said B-measurement is greater than said A-measurement, the output of said forward-reverse counter being a signal corresponding to a specific pulse-train frequency.

Claim 5

A pulse-train generator as in claim 1, wherein said pulse-train generator comprises a pulsed-output frequency synthesizer, the frequency of its output pulse train being determined by the command-signal input received from said frequency changing means.

Claim 6

A pulse-train generator as in claim 2, wherein said frequency-changing means further includes control circuit means for controlling the timing of said counter, registers and comparator so that they complete a cycle of two successive time-intervals measurements and are then cleared and reset to complete a cycle of the next two time-interval measurements.

Claim 7

A pulsE-train generator as in claim 4, wherein the output of said comparator is a single pulse and the output of said frequency-changing means is a binary-coded digital signal.

Claim 8

In combination with a pulse-train generator as defined in claim 1 having an output whose frequency is automatically locked to the frequency of its input pulse train, a frequency-measuring circuit for measuring the frequency of the input pulse train comprising a numerical indicator for indicating the value of a binary-coded digital signal.

Claim 9

A combination as set forth in claim 7, wherein said numerical indicator comprises a binary-coded digital signal decoder and a display device for displaying the output signal of said decoder.

Claim 10

A pulse-train generator having an output whose frequency is automatically locked to the frequency of its input pulse train comprising, in combination: frequency-comparison means including an input-output counter, a pair of store registers called an A-store and a B-store register, a comparator and control circuit means, said counter being fed the input and output pulse trains and measuring the time interval between each input pulse and the next succeeding output pulse, said time-interval measurements being made in pairs, said A-store register registering the first time-interval measurement of a pair and said B-store register registering the second time-interval measurement of a pair, said comparator being fed the store-register outputs and comparing them to determine whether the A-store measurement is larger than the B-store measurement, or vice versa, said control circuit means including logic components for timing the operations of said counter, registers and comparator whereby the counter, registers and comparator are operated to make said time-interval measurements for a pair of input and output pulses and then are reset to make the same measurements for the next pair of pulses; frequency-changing means comprising a forward-reverse counter, a pulse from said comparator being fed to the forward terminal if said B-store measurement is larger than said A-store measurement and to the reverse terminal if said A-store measurement is the larger, the output of said counter being a binary-coded, digital signal corresponding to a specific pulse-train frequency; and pulse-train generator means comprising a free-running, pulsed-output frequency synthesizer, the frequency of its output pulse train being determined by the output signal of said forward-reverse counter which feeds the synthesizer its input command signal.

Claim 11

A pulse-train generator having an output whose frequency is automatically locked to the frequency of its input pulse train comprising, in combination: frequency-comparison means including an input-output counter, a pair of store registers called an A-store and a B-store register, a comparator and control circuit means, said counter being fed the input and output pulse trains and measuring the time interval between each input pulse and the next succeeding output pulse, said time-interval measurements being made in pairs, said A-store register registering the first time-interval measurement of a pair and said B-store register registering the second time-interval measurement of a pair, said comparator being fed the store-register outputs and comparing them to determine whether the A-store measurement is larger than the B-store measurement, or vice versa, said control circuit means including logic components for timing the operations of said counter, registers and comparator whereby the counter, registers and comparator are operated to make said time-interval measurements for a pair of input and output pulses and then are reset to make the same measurements for the next pair of pulses; frequency-changing means comprising a forward-reverse counter, a pulse from said comparator being fed to the forward terminal if said B-store measurement is larger than said A-store measurement and to the reverse terminal if said A-store measurement is the larger, the output of said counter being a binary-coded, digital signal corresponding to a specific pulse-train frequency; and pulse-train generator means comprising a free-running, pulsed-output frequency synthesizer, the frequency of its output pulse train being determined by the output signal of said forward-reverse counter which feeds the synthesizer its input command signal.