Frequency control of oscillators using digital techniques

Claim 2

Apparatus for controlling the frequency of an oscillator, comprising, a. first means coupled to said oscillator and responsive to said frequency for storing a first number therein indicative of the value of said frequency during a predetermined interval, b. second means coupled to said oscillator and responsive to said first number representative of said frequency as stored in said first means, said second means responsive to said frequency for (comparing) counting backward from said stored number (with a second number obtained) during a second interval equal to said predetermined interval whereby any difference in said frequency is determined by said second means, and (and) c. control means coupled to said oscillator and responsive to said any difference (between said first and second number) to correct the frequency (thereof) of said oscillator in a direction towards said first number.

Claim 3

The apparatus according to claim 1, further including, a. means coupled to said second means and responsive to said frequency of said oscillator being controlled by said control means according to said difference for introducing a given error in terms of frequency therein to thereby cause said oscillator to be synchronized within a predetermined limit from said first number.

Claim 4

The apparatus according to claim 1, further including, a. means coupled to said first means and responsive to said frequency of said oscillator being controlled by said control means for introducing a given error in terms of frequency therein to thereby cause said oscillator to be synchronized within a predetermined limit from said first number.

Claim 5

Apparatus for controlling the frequency of a tunable oscillator, said oscillator being capable of (providing) selecting any one of a plurality of frequencies, each one of which can very from a preselected tuned value during a given period of time, comprising: a. first counting means responsive to said one selected frequency for storing therein a number indicative of said frequency during a predetermined interval, b. down counting means capable of storing therein any number stored by said first counting means and operative to count down from said number by a given integer for each pulse of a series applied to an input thereof, c. means coupling said first counting means to said down counting means for transferring said number stored in said first counting means to said down counting means, d. means coupled to said input of said down counting means and responsive to said one selected frequency for applying a series of pulses thereto representative of said frequency and for (said) a second interval substantially equal to said predetermined interval, whereby if said selected frequency did not vary, said down counting means would indicate zero at the end of said second interval, e. detector means coupled to said down counting means and responsive to any number stored in said down counting means at the end of said second interval to provide a control signal indicative of the polarity and magnitude of said frequency variation, and f. means coupling said detector means to said oscillator and responsive to said control signal for varying the frequency of said oscillator in a direction to tend to cause said down counting means to indicate zero at the end of said second interval.

Claim 6

Apparatus for controlling the frequency of a tunable oscillator, said oscillator being capable of (providing) selecting any one of a plurality of frequencies, each one of which can very from a preselected tuned value during a given period of time, comprising: a. first counting means responsive to said one selected frequency for storing therein a number indicative of said frequency during a predetermined interval, b. down counting means capable of storing therein any number stored by said first counting means and operative to count down from said number by a given integer for each pulse of a series applied to an input thereof, c. means coupling said first counting means to said down counting means for transferring said number stored in said first counting means to said down counting means, d. means coupled to said input of said down counting means and responsive to said one selected frequency for applying a series of pulses thereto representative of said frequency and for (said) a second interval substantially equal to said predetermined interval, whereby if said selected frequency did not vary, said down counting means would indicate zero at the end of said second interval, e. detector means coupled to said down counting means and responsive to any number stored in said down counting means at the end of said second interval to provide a control signal indicative of the polarity and magnitude of said frequency variation, and f. means coupling said detector means to said oscillator and responsive to said control signal for varying the frequency of said oscillator in a direction to tend to cause said down counting means to indicate zero at the end of said second interval.

Claim 7

The apparatus according to claim 4 further comprising, a. a frequency divider responsive to said oscillator frequency for dividing the same by a given integer prior to application of said one selected frequency to said first counting means.

Claim 8

The apparatus according to claim 5 further including, a. means coupled to said frequency Divider for presetting said divider to a given number prior to the application of said oscillator frequency thereto.

Claim 9

The apparatus according to claim 5 wherein said frequency divider is a binary counter.

Claim 10

The apparatus according to claim 4 wherein said detector means comprises: a. first and second binary multivibrators, each having two stable states and capable of being selectively operated to be in any one of said states according to a signal applied to an input thereof, b. said first binary multivibrator having said input coupled to that portion of said down counting means which stores the most significant digits of said number for determining the polarity of said frequency variation, and c. said second binary multivibrators having said input coupled to that portion of said down counting means which stores the least significant digits of said number for determining the magnitude of said frequency variation.

Claim 11

The apparatus according to claim 4 wherein said means coupling said detector to said oscillator includes, a. an integrator having an input terminal responsive to said control signal for providing at an output terminal an integrated version of said control signal, and b. a variable reactance device coupling said integrator output terminal to said oscillator for varying the frequency thereof according to said integrated version of said control signal.

Claim 12

The apparatus according to claim 9 further comprising, a. a variable attenuator coupling said output terminal of said integrator to a source of reference potential for selectively varying said integrated signal at said output terminal, and b. means for varying said attenuator and therefore said control signal according to said tuning of said oscillator.

Claim 13

Apparatus for controling the frequency of an oscillator which frequency can undesirably change over a given period of time comprising: a. first counting means responsive to said frequency for storing therein a number indicative of the value of said frequency during a given interval, b. down counting means operative to decrease a number stored therein by a given integer for each one pulse of a series of pulses to be applied to an input thereof, c. means coupling said first counting means to said down counting means for transferring said number stored by said first counting means to said down counting means, d. means coupled to said input of said down counting means responsive to said frequency for applying to said input of said down counting means a series of pulses representative of said frequency and for a second interval substantially equal to said given interval, whereby if the frequency of said oscillator remained stable, said down counting means would indicate a zero condition at the end of said (given) second interval, e. an error polarity detector coupled to said down counting means for determining the polarity of said frequency change during said second interval, f. an error magnitude detector coupled to said down counting means for determining the magnitude of said frequency change during said second interval, and go control means coupling said error polarity detector and said error magnitude detector to said oscillator for varying the frequency thereof in a direction to cause said down counting means to indicate zero at the end of said second interval.

Claim 14

Apparatus for controling the frequency of an oscillator which frequency can undesirably change over a given period of time comprising: a. first counting means responsive to said frequency for storing therein a number indicative of the value of said frequency during a given interval, b. down counting means operative to decrease a number stored therein by a given integer for each one pulse of a series of pulses to be applied to an input thereof, c. means coupling said first counting means to said down counting means for transferring said number stored by said first counting means to said down counting means, d. means coupled to said input of said down counting means responsive to said frequency for applying to said input of said down counting means a series of pulses representative of said frequency and for a second interval substantially equal to said given interval, whereby if the frequency of said oscillator remained stable, said down counting means would indicate a zero condition at the end of said (given) second interval, e. an error polarity detector coupled to said down counting means for determining the polarity of said frequency change during said second interval, f. an error magnitude detector coupled to said down counting means for determining the magnitude of said frequency change during said second interval, and go control means coupling said error polarity detector and said error magnitude detector to said oscillator for varying the frequency thereof in a direction to cause said down counting means to indicate zero at the end of said second interval.

Claim 15

The apparatus according to claim 11 further comprising, a. a binary divider having an input coupled to said oscillator for dividing the frequency thereof by a preselected integer prior to application of said frequency to said first counting means, and b. means coupled to said binary divider for presetting said divider by a given amount to thereby introduce a given error into said first counting means.

Claim 16

Apparatus for controlling the frequency of an oscillator comprising: a. first means coupled to said oscillator and operative during a first interval to store a number therein representative oF the frequency of said oscillator and operative during a second interval substantially equal to said first interval for counting down from said stored number, whereby if said frequency of said oscillator varied during said second interval, said means would provide a numerical indication of said variation at the end of said second interval, b. means coupled to said oscillator and responsive to said numerical indication to vary the frequency of said oscillator in a direction so that said numerical indication approaches zero during said second interval.

Claim 17

Apparatus for controlling the frequency of an oscillator comprising: a. first means coupled to said oscillator and operative during a first interval to store a number therein representative oF the frequency of said oscillator and operative during a second interval substantially equal to said first interval for counting down from said stored number, whereby if said frequency of said oscillator varied during said second interval, said means would provide a numerical indication of said variation at the end of said second interval, b. means coupled to said oscillator and responsive to said numerical indication to vary the frequency of said oscillator in a direction so that said numerical indication approaches zero during said second interval.

Claim 18

Apparatus for controlling the frequency of an oscillator, comprising: a. first means coupled to said oscillator and operative during a first interval to store a number therein indicative of the frequency of said oscillator, and operative during a second interval substantially equal to said first interval for counting down from said stored number, whereby if said frequency of said oscillator varied, said means would have stored therein a count at the end of said second interval indicative of said variation, b. detector means coupled to said first means and responsive to the magnitude of said stored count to provide a control signal determinative of the polarity and magnitude of said frequency variation of said oscillator, and c. control means coupled to said oscillator and responsive to said control signal for varying the frequency of said oscillator at a rate and in a direction to cause said stored count to approach zero during said second interval.

Claim 19

Apparatus for controlling the frequency of an oscillator, comprising: a. first means coupled to said oscillator and operative during a first interval to store a number therein indicative of the frequency of said oscillator, and operative during a second interval substantially equal to said first interval for counting down from said stored number, whereby if said frequency of said oscillator varied, said means would have stored therein a count at the end of said second interval indicative of said variation, b. detector means coupled to said first means and responsive to the magnitude of said stored count to provide a control signal determinative of the polarity and magnitude of said frequency variation of said oscillator, and c. control means coupled to said oscillator and responsive to said control signal for varying the frequency of said oscillator at a rate and in a direction to cause said stored count to approach zero during said second interval.