Autopilot radio guidance signal circuit including controlled integrator

Claim 2

A radio command signal circuit for an aircraft autopilot comprising: means supplying a radio guidance signal the amplitude and polarity of which is related to the displacement of the aircraft off the desired radio course; integrating means providing an output proportional to the time integral of said radio guidance signal, said integrating means having control means for rendering said output zero; means supplying said radio guidance signal and said output of said integrating means to the autopilot to cause said autopilot to steer the aircraft in a direction to reduce the amplitude of said radio guidance signal; threshold means for actuating said integrating means control, said threshold means being operative at signal levels of said radio guidance signal equalling or exceeding a first upper level to hold output from said integrating means at zero and being operative at a second lower level for momentarily rendering output from said integrating means zero; and means for setting said second lower level of said threshold means at one value when the source of said radio guidance signals is VOR and at a second value when the source of said radio guidance signals is ILS.

Claim 3

A command signal circuit as claimed in claim 1, with additionally, means controlled by said threshold means for changing the proportionality of output to input of said integrating means when the source of said radio guidance signals is ILS and when the signal level of radio guidance signal equals or is below said second value of said second lower level.

Claim 4

A radio command signal circuit for an aircraft autopilot, comprising: an integrator including an amplifier, an input impedance and a capacitor connected in inverse feedback relationship; a first switching transistor connected to short circuit said capacitor when conductive; a second switching transistor for interrupting input to said amplifier when non-conductive; a third switching transistor connected to alter the value of said input impedance when conductive; threshold means responsive to the signal level of radio guidance signals, said signal level varying as the displacement off course of the aircraft guided by said signal, said threshold means causing conduction of said first transistor when said signal level equals or exceeds a first value corresponding to a relatively large error in the aircraft course, said threshold means causing momentary conduction of said first transistor whenever said signal level diminishes to a second value corresponding to a relatively small error in the aircraft course; means normally rendering said second transistor conductive and said third transistor non-conductive; means applying the radio guidance signal to said input impedance of said integrator; and, means combining output of said integrator amplifier with the radio guidance signal to provide command signal to the autopilot.

Claim 5

A radio command signal circuit for an aircraft autopilot, comprising: an integrator including an amplifier, an input impedance and a capacitor connected in inverse feedback relationship; a first switching transistor connected to short circuit said capacitor when conductive; a second switching transistor for interrupting input to said amplifier when non-conductive; a third switching transistor connected to alter the value of said input impedance when conductive; threshold means responsive to the signal level of radio guidance signals, said signal level varying as the displacement off course of the aircraft guided by said signal, said threshold means causing conduction of said first transistor when said signal level equals or exceeds a first value corresponding to a relatively large error in the aircraft course, said threshold means causing momentary conduction of said first transistor whenever said signal level diminishes to a second value corresponding to a relatively small error in the aircraft course; means normally rendering said second transistor conductive and said third transistor non-conductive; means applying the radio guidance signal to said input impedance of said integrator; and, means combining output of said integrator amplifier with the radio guidance signal to provide command signal to the autopilot.

Claim 6

A command signal circuit as claimed in claim 3, with additionally, means for selecting a different value of said second value of signal level at which said threshold means responds according to whether the source of radio guidance signal is VOR or ILS.

Claim 7

A command signal circuit as claimed in claim 4 wherein said threshold means responding to said second value of signal level for radio guidance signals from ILS renders said third transistor continuously conductive and said second transistor non-conductive for a limited time.