Method and apparatus for determining the rate of change of a time interval

Claim 5

The invention as in claim 2 wherein the correlating step is accomplished by gating an oscillator on with that portion of said pulse representing the start of said time interval, said oscillator thereby producing an oscillatory output signal.

Claim 6

The invention as in claim 3 wherein the leading edge of said pulse represents the start of said time interval and the trailing edge of said pulse represents the end of said time interval.

Claim 7

The invention as in claim 4 wherein said oscillator is phase coherent and is always gated on in consistent phase relationship with the start of the time interval.

Claim 8

The invention as in claim 5 wherein said oscillator output signal is sampled by gating on a sampling gate due to the presence of the trailing edge of the pulse representing the end of the time interval, said sampling gate operable to pass the sampled voltage level of the oscillator output at the instant in time that said end of the time interval occurred, thereby initiating the forming of said second signal in response to preselected phases of said oscillator voltage.

Claim 9

The invention as in claim 4 wherein said pulse is a function of the distance from an airborne transmitter/receiver to a ground station receiver/transmitter.

Claim 10

The invention as in claim 7 wherein said oscillator is phase coherent and is always gated on in consistent phase relationship with the start of the time interval.

Claim 11

The invention as in claim 7 wherein said oscillator output signal is sampled by gating on a sampling gate due to the presence of the trailing edge of the pulse representing the end of the time interval, said sampling gate operable to pass the sampled voltage level of the oscillator output at the instant in time that said end of the time interval occurred, thereby initiating the forming of said second signal in response to preselected phases of said oscillator voltage.

Claim 12

In distance/ground speed measuring equipment capable of producing a pulse whose time duration from leading edge to trailing edge is a function of the distance from the airborne receiver to a ground transmitter, the improvement comprising means for producing an output signal having a periodic wave form, means for synchronizing said wave form with the leading edge of said pulse, means for producing a second output signal in response to the level of the wave form at the time of occurrence of said trailing edge of said pulse, and means operable as a function of the frequency of said second output signal for indicating the ground speed of said airborne receiver relative to said ground transmitter.

Claim 13

In distance/ground speed measuring equipment capable of producing a pulse whose time duration from leading edge to trailing edge is a function of the distance from the airborne receiver to a ground transmitter, the improvement comprising means for producing an output signal having a periodic wave form, means for synchronizing said wave form with the leading edge of said pulse, means for producing a second output signal in response to the level of the wave form at the time of occurrence of said trailing edge of said pulse, and means operable as a function of the frequency of said second output signal for indicating the ground speed of said airborne receiver relative to said ground transmitter.

Claim 14

The invention as in claim 10 wherein said first signal producing means and said synchronizing means include an oscillator, said oscillator operable to produce said first output signal, and means for gating on said oscillator due to the time occurrence of said leading edge of said pulse, said oscillator when gated on thereby producing said output signal having said periodic wave form.

Claim 15

The invention as in claim 10 wherein said means for producing said second output signal includes a sampling gate receiving said first output signal, and means for turning on said sampling gate due to the time occurrence of said trailing edge of said pulse, said sampling gate thereby passing voltage levels of said first signal at its turn on instant.

Claim 16

The invention as in claim 10 including means for measuring the frequency of said second output signal, said indicating means operable to indicate said frequency as the relative ground speed of said airborne receiver.

Claim 17

In distance/ground speed measuring equipment capable of producing a pulse whose time duration from leading edge to trailing edge is a function of the distance from an airborne receiver to a ground transmitter, the improvement comprising an oscillator, means for gating on said oscillator due to the time occurrence of said leading edge of said pulse, said oscillator when gated on having a running oscillatory output, a sampling gate connected to the output of said oscillator, means for turning on said sampling gate due to the time occurrence of said trailing edge of said pulse, said sampling gate thereby operable to pass voltage levels of said oscillator output at its turn on instant, means for producing an output signal in response to levels of said voltage pass through said gate, means for measuring the frequency of said last named output signal, and means for indicating said measured frequency in terms of ground speed of said airborne receiver relative to said ground transmitter.

Claim 18

In distance/ground speed measuring equipment capable of producing a pulse whose time duration from leading edge to trailing edge is a function of the distance from an airborne receiver to a ground transmitter, the improvement comprising an oscillator, means for gating on said oscillator due to the time occurrence of said leading edge of said pulse, said oscillator when gated on having a running oscillatory output, a sampling gate connected to the output of said oscillator, means for turning on said sampling gate due to the time occurrence of said trailing edge of said pulse, said sampling gate thereby operable to pass voltage levels of said oscillator output at its turn on instant, means for producing an output signal in response to levels of said voltage pass through said gate, means for measuring the frequency of said last named output signal, and means for indicating said measured frequency in terms of ground speed of said airborne receiver relative to said ground transmitter.

Claim 19

The invention as in claim 14 wherein said oscillator is a phase coherent gated oscillator that is always gated on at the same phase angle.

Claim 20

The invention as in claim 15 wherein said trailing edge of said pulse is operable to turn said gated oscillator off, and including a means for delaying said time occurrence of said trailing edge to eliminate oscillator wave distortion at said sampling instant.

Claim 21

The invention as in claim 14 wherein said last named output signal producing means includes a squaring amplifier that is responsive to preselected levels of said voltage passed through said gate, said amplifier having an output change of state when said preselected voltage levels are applied thereto.

Claim 22

The invention as in claim 17 wherein said output from said squaring amplifier is used to trigger a monostable, and a filter connected to said monostable, said filter operable to extract a voltage component whose value is a function of the frequency of said squaring amplifier output.

Claim 23

The invention as in claim 18 wherein said distance measuring equipment operates in either a search mode or a track mode and wherein said improvement includes a means for disabling said monostable during said search mode of operation.