Ranging system using phase detection

Claim 2

An electronic ranging system comprising signal transmitting means for directing a carrier signal toward a reflecting target, modulating means for modulating said carrier signal, signal receiving means for receiving reflections of the modulated carrier signal, and phase detection means for determining the phase shift resulting from the distance traveled by said modulated carrier signal from said signal transmitting means to said signal receiving means, said phase detection means including a voltage controlled phase shifting means connected to the modulating means, synchronous detector means connected to said phase shifting means and said signal receiving means, said detector means operating at the frequency of the modulation to detect only received signals having the same modulation frequency, and an integrator receiving the output of said synchronous detector means, said integrator producing a DC output signal representative of the phase shift resulting from the distance traveled by said modulation, the output of said integrator being connected to said phase shifting means and to an output terminal.

Claim 3

The ranging system of claim 1 in which the phase shifting means comprises a ramp generator connected to said modulating means for generating a repeating ramp function having a ramp increasing at a substantially linear rate, and a comparator connected to said ramp generator and said integrator, said comparator comparing the integrator output voltage with the instantaneous voltage of said ramp to produce an alternating signal having a phase determined by the integrator output voltage.

Claim 4

The ranging system of claim 2 in which the modulating means comprises an oscillator operating at twice the frequency of said modulation and a dividing means connected between said oscillator and said transmitting means for reducing oscillator frequency to modulation frequency, and the phase detection means comprises a second dividing means connected to said comparator for reducing the alternating signal from said comparator to modulation frequency, said second dividing means also squaring the comparator signal along the time axis.

Claim 5

The ranging system of claim 3 comprising a phaser connected between said first and second dividing means to establish a predetermined initial phase relationship between the outputs of said dividing means.

Claim 6

The ranging system of claim 4 comprising a low pass filter connected between said integrator and said comparator, said output terminal being connected between said filter and said comparator.

Claim 7

The ranging system of claim 5 comprising a second output terminal connected between said detector and said integrator, said second output terminal displaying a DC voltage representative of the rate of change of said range.

Claim 8

The ranging system of claim 6 comprising a second phase shifting means for shifting the phase of the transmitted modulation in response to the voltage of the integrator.

Claim 9

The ranging system of claim 7 in which the second phase shifting means shifts the phase of the transmitted modulation in the opposite direction of the first phase shifting means.

Claim 10

The ranging system of claim 1 comprising a second output terminal connected between said detector and said integrator, said second output terminal displaying a DC voltage representative of the rate of change of said range.

Claim 11

The ranging system of claim 1 comprising a second phase shifting means for shifting the phase of the transmitted modulation in response to the Voltage of the integrator.

Claim 12

A ranging system for determining the available headway of an automotive vehicle comprising signal transmitting means located on said vehicle for directing a carrier signal forward of the vehicle, modulating means connected to said transmitting means for modulating said carrier signal, signal receiving means located on said vehicle for receiving reflections of the modulated carrier signal from a target located forwardly of said vehicle, synchronous detector means connected to said modulating means and said receiving means, said detector means multiplying receiving means output by a waveform obtained from said modulating means to produce a net DC voltage representative of the phase difference between the modulation and any signal in the receiving means output having the same frequency as the modulation, integrator means for integrating detector means output with respect to time, said integrator means producing a DC output voltage that is applied to an output terminal, said DC voltage at said output terminal being representative of available headway, and phase shifting means connected to said integrator means for shifting the phase of the waveform obtained from the modulating means according to the output of the integrator means, the output of said phase shifting means being applied to the detector means.

Claim 13

A ranging system for determining the available headway of an automotive vehicle comprising signal transmitting means located on said vehicle for directing a carrier signal forward of the vehicle, modulating means connected to said transmitting means for modulating said carrier signal, signal receiving means located on said vehicle for receiving reflections of the modulated carrier signal from a target located forwardly of said vehicle, synchronous detector means connected to said modulating means and said receiving means, said detector means multiplying receiving means output by a waveform obtained from said modulating means to produce a net DC voltage representative of the phase difference between the modulation and any signal in the receiving means output having the same frequency as the modulation, integrator means for integrating detector means output with respect to time, said integrator means producing a DC output voltage that is applied to an output terminal, said DC voltage at said output terminal being representative of available headway, and phase shifting means connected to said integrator means for shifting the phase of the waveform obtained from the modulating means according to the output of the integrator means, the output of said phase shifting means being applied to the detector means.

Claim 14

The ranging system of claim 11 in which the phase shifting means comprises a ramp generator connected to said modulating means for generating a repeating ramp function having a ramp increasing at a substantially linear rate, and a comparator connected to said ramp generator and said integrator, said comparator comparing the integrator output voltage with the instantaneous voltage of said ramp to produce an alternating signal having a phase determined by the integrator output voltage.

Claim 15

The ranging system of claim 12 in which the modulating means comprises an oscillator operating at twice the frequency of said modulation and a dividing means connected between said oscillator and said transmitting means for reducing oscillator frequency to modulation frequency, and comprising a second dividing means connected between said comparator and said synchronous detector means for reducing the alternating signal from said comparator to modulation frequency, said second dividing means also squaring the comparator signal along the time axis.

Claim 16

The ranging system of claim 13 comprising a phaser connected between said first and second dividing means to establish a predetermined initial phase relationship between the outputs of said dividing means.

Claim 17

The ranging system of claim 14 comprising a low pass filter connected between said integrator and said comparator, said output terminal being connected between said filter and said comparator.

Claim 18

The ranging system of claim 15 comprising a second output terminal connected between said detector and said integrator, said second output terminal displaying a DC voltage representative of the rate of change of said available headway.

Claim 19

The ranging system of claim 16 comprising a second phase shifting means for shifting the phase of the transmitted modulation in response to the voltage of the integrator.

Claim 20

The ranging system of claim 17 in which the second phase shifting means shifts the phase of the transmitted modulation in the opposite direction of the first phase shifting means.

Claim 21

The ranging system of claim 11 comprising a second output terminal connected between said detector and said integrator, said second output terminal displaying a DC voltage representative of the rate of change of said available headway.

Claim 22

The ranging system of claim 11 comprising a second phase shifting means for shifting the phase of the transmitted modulation in response to the voltage of the integrator.

Claim 23

The ranging system of claim 20 in which the second phase shifting means shifts the phase of the transmitted modulation in the opposite direction Of the first phase shifting means.