Automatic frequency control circuit for frequency agile radar

Claim 2

A fine correction automatic frequency control circuit for frequency agile radar system, comprising: pulse generator means connected to said radar system, receiving an IF envelope therefrom, and producing an output pulse of time duration equivalent to a fixed number of periods of the IF; first and second oscillators of different fixed frequencies connected to and controlled by said pulse generator means, said first oscillator being of a less frequency than said second oscillator and said first oscillator being actuated by a leading edge of said output pulse while said second oscillator is actuated by a trailing edge thereof; and error detection means connected to said oscillators for sensing the phase differentials of the outputs thereof and creating a correction signal for application to said radar system dependent upon said phase differential.

Claim 3

The fine correction automatic frequency control circuit as recited in claim 1 wherein said error detection means includes a counter connected to one of said oscillators and a coincidence detector interconnected between said oscillators and said counter to inhibit said counter when transitions of the outputs of the oscillators are coincident.

Claim 4

The fine correction automatic frequency control circuit as recited in claim 2 which further includes a digital to analog converter connected to and converting the output of said counter.

Claim 5

The fine correction automatic frequency control circuit as recited in claim 1 wherein said pulse generator means includes a timedelayed one shot triggered by the initial pulse in the IF envelope.

Claim 6

An automatic frequency control circuit for use in a frequency agile radar system transmitting radar signals within an IF envelope, comprising: first oscillator means enabled by an IF pulse and connected to said radar system for producing an output of a first frequency during said IF envelope; second oscillator means enabled by an IF pulse subsequent to that enabling said first oscillator means and connected to said radar system for producing an output of a second frequency during said IF envelope; and coincidence detection means connected to said first and second oscillator means for receiving the outputs thereof and producing a frequency correction signal dependent upon the time of coincidence of transition points of the output pulses of said first and second oscillator means and wherein said coincidence detection means includes a counter connected to one of said oscillator means and counting output pulses thereof until said time of coincidence of transition points.

Claim 7

An automatic frequency control circuit for use in a frequency agile radar system transmitting radar signals within an IF envelope, comprising: first oscillator means enabled by an IF pulse and connected to said radar system for producing an output of a first frequency during said IF envelope; second oscillator means enabled by an IF pulse subsequent to that enabling said first oscillator means and connected to said radar system for producing an output of a second frequency during said IF envelope; and coincidence detection means connected to said first and second oscillator means for receiving the outputs thereof and producing a frequency correction signal dependent upon the time of coincidence of transition points of the output pulses of said first and second oscillator means and wherein said coincidence detection means includes a counter connected to one of said oscillator means and counting output pulses thereof until said time of coincidence of transition points.

Claim 8

The automatic frequency control circuit as recited in claim 5 wherein said coincidence detection means includes a digital to analog converter connected to said counter for producing said frequency correction signal as an analog signal.

Claim 9

The automatic frequency control circuit as recited in claim 5 which further includes a time-delayed one shot connected to said first and second oscillator means for producing an output signal, the leading edge of which activates said first oscillator means and the trailing edge of which activates said second oscillator means.