Electronic automatic frequency tuning system

Claim 2

An electronic system for automatically tuning an oscillator to a selected frequency comprising: a referencE signal generator for generating a signal having a comb of reference frequencies; a controllable oscillator; oscillator control means for controlling the frequency of said oscillator; mixer means for receiving signals from said signal generator and said oscillator and heterodyning same to produce an output signal having sum and difference frequencies; tuned circuit means for receiving signals from said mixer means and for passing signals having a narrow band of frequencies centered about a predetermined beat frequency; programmable means for receiving information designating said selected frequency, cooperable with said oscillator control means to initiate a frequency sweep of said oscillator beginning at an initial frequency, for detecting and counting occurrences of said predetermined beat frequency during said frequency sweep of said oscillator, and for causing said oscillator control means to terminate said frequency sweep of said oscillator upon detecting and counting a number of occurrences of said beat frequency determined by the information designating said selected frequency; and discriminator means continuously connected to said tuned circuit means and to said oscillator control means for providing an output indicative of whether the signal passed by said tuned circuit means has a frequency above or below said predetermined beat frequency and effective upon termination of said frequency sweep of said oscillator to cause said oscillator control means to stabilize the frequency of said local oscillator at said selected frequency.

Claim 3

An electronic system for automatically tuning an oscillator to a selected frequency comprising: a reference signal generator for generating a signal having a comb of reference frequencies; a controllable oscillator; oscillator control means for controlling the frequency of said oscillator; mixer means for receiving signals from said signal generator and said oscillator and heterodyning same to produce an output signal having sum and difference frequencies; tuned circuit means for receiving signals from said mixer means and for passing signals having a narrow band of frequencies centered about a predetermined beat frequency; programmable means for receiving information designating said selected frequency, cooperable with said oscillator control means to initiate a frequency sweep of said oscillator beginning at an initial frequency, for detecting and counting occurrences of said predetermined beat frequency during said frequency sweep of said oscillator, and for causing said oscillator control means to terminate said frequency sweep of said oscillator upon detecting and counting a number of occurrences of said beat frequency determined by the information designating said selected frequency; discriminator means connected to said tuned circuit means and to said oscillator control means for providing an output indicative of whether the signal passed by said tuned circuit means has a frequency above or below said predetermined beat frequency and effective upon termination of said frequency sweep of said oscillator to cause said oscillator control means to stabilize the frequency of said local oscillator at said selected frequency; and an inverting/noninverting amplifier connecting said discriminator means to said oscillator control means.

Claim 4

An electronic system for automatically tuning an oscillator to a selected frequency comprising: a reference signal generator for generating a signal having a comb of reference frequencies; a controllable oscillator; oscillator control means for controlling the frequency of said oscillator; mixer means for receiving signals from said signal generator and said oscillator and heterodyning same to produce an output signal having sum and difference frequencies; tuned circuit means for receiving signals from said mixer means and for passing signals having a narrow band of frequencies centered about a predetermined beat frequency; programmable means for receiving information designating said selected frequency, cooperable with said oscillator control means to initiate a frequency sweep of said oscillator beginning at an initial frequency, for detecting and counting occurrences of said predetermined beat frequency during said frequency sweep of said oscillator, and for causing said oscillator control means to terminate said frequency sweep of said oscillator upon detecting and counting a number of occurrences of said beat frequency determined by the information designating said selected frequency; discriminator means connected to said tuned circuit means and to said oscillator control means for providing an output indicative of whether the signal passed by said tuned circuit means has a frequency above or below said predetermined beat frequency and effective upon termination of said frequency sweep of said oscillator to cause said oscillator control means to stabilize the frequency of said local oscillator at said selected frequency; and an inverting/noninverting amplifier connecting said discriminator means to said oscillator control means.

Claim 5

The invention according to claim 2 wherein the mode of operation of said inverting/noninverting amplifier is controlled by said programmable means.

Claim 6

An electronic system for automatically tuning an oscillator to a selected frequency comprising: a reference signal generator for generating a signal having a comb of reference frequencies; a controllable oscillator; oscillator control means for controlling the frequency of said oscillator; mixer means for receiving signals from said signal generator and said oscillator and heterodyning same to produce an output signal having sum and difference frequencies; tuned circuit means for receiving signals from said mixer means and for passing signals having a narrow band of frequencies centered about a predetermined beat frequency; programmable means for receiving information designating said selected frequency, cooperable with said oscillator control means to initiate a frequency sweep of said oscillator beginning at an initial frequency, for detecting and counting occurrences of said predetermined beat frequency during said frequency sweep of said oscillator, and for causing said oscillator control means to terminate said frequency sweep of said oscillator upon detecting and counting a number of occurrences of said beat frequency determined by the information designating said selected frequency; discriminator means connected to said tuned circuit means and to said oscillator control means for providing an output indicative of whether the signal passed by said tuned circuit means has a frequency above or below said predetermined beat frequency and effective upon termination of said frequency sweep of said oscillator to cause said oscillator control means to stabilize the frequency of said local oscillator at said selected frequency; a second discriminator associated with a receiver; a switch connected to said first identified discriminator, said oscillator control means, and to said second discriminator; and said switch being operable to selectively connect said first identified discriminator and said second discriminator to said oscillator control means.

Claim 7

An electronic system for automatically tuning an oscillator to a selected frequency comprising: a reference signal generator for generating a signal having a comb of reference frequencies; a controllable oscillator; oscillator control means for controlling the frequency of said oscillator; mixer means for receiving signals from said signal generator and said oscillator and heterodyning same to produce an output signal having sum and difference frequencies; tuned circuit means for receiving signals from said mixer means and for passing signals having a narrow band of frequencies centered about a predetermined beat frequency; programmable means for receiving information designating said selected frequency, cooperable with said oscillator control means to initiate a frequency sweep of said oscillator beginning at an initial frequency, for detecting and counting occurrences of said predetermined beat frequency during said frequency sweep of said oscillator, and for causing said oscillator control means to terminate said frequency sweep of said oscillator upon detecting and counting a number of occurrences of said beat frequency determined by the information designating said selected frequency; discriminator means connected to said tuned circuit means and to said oscillator control means for providing an output indicative of whether the signal passed by said tuned circuit means has a frequency above or below said predetermined beat frequency and effective upon termination of said frequency sweep of said oscillator to cause said oscillator control means to stabilize the frequency of said local oscillator at said selected frequency; a second discriminator associated with a receiver; a switch connected to said first identified discriminator, said oscillator control means, and to said second discriminator; and said switch being operable to selectively connect said first identified discriminator and said second discriminator to said oscillator control means.

Claim 8

The invention according to claim 1 further comprising means for adjusting said initial frequency.

Claim 9

In an electronic system for automatically tuning to a selected frequency, said system having a reference signal generator and having an oscillator control means, a controllable oscillator, a mixer, and a discriminator connected in a loop for stabilizing the frequency of said oscillator, an inverting/noninverting amplifier connecting said discriminator to said oscillator control means and operable to stabilize said local oscillator at a frequency a predetermined difference frequency to one side of a reference frequency when operating in the noninverting mode and to stabilize said local oscillator frequency at a frequency a predetermined difference frequency to the other side of said reference frequency when operating in the inverting mode.

Claim 10

In an electronic system for automatically tuning to a selected frequency, said system having a reference signal generator and having an oscillator control means, a controllable oscillator, a mixer, and a discriminator connected in a loop for stabilizing the frequency of said oscillator, an inverting/noninverting amplifier connecting said discriminator to said oscillator control means and operable to stabilize said local oscillator at a frequency a predetermined difference frequency to one side of a reference frequency when operating in the noninverting mode and to stabilize said local oscillator frequency at a frequency a predetermined difference frequency to the other side of said reference frequency when operating in the inverting mode.

Claim 11

The invention according to claim 6 further comprising programmable means for receiving information designating said selected frequency and for controlling the mode of operation of said inverting/noninverting amplifier.