Communication apparatus having a ranging capability

Claim 2

A Communication and ranging apparatus, comprising: A. first means for developing an output signal which is proportional to the product of first and second input signals, B. said first input signal comprising a modulated radio frequency signal, C. detection means responsive to said output signal for developing as an output a signal which is proportional to the energy of said output signal at the carrier frequency of said modulated radio frequency signal, D. said second input signal comprising a signal at the modulating frequency of said radio frequency signal, and E. means responsive to the output of said detection means for varying the phase of said second input such that the output of said detection means is reduced to substantially zero whereby said second input signal is locked in phase with the phase of the modulation on said first input signal.

Claim 3

The apparatus according to claim 1, further comprising; F. means for transmitting said second input signal to the source of said modulated radio frequency signal, G. second means at the source of said modulated radio frequency signal for developing an output signal which is proportional to the product of said second input signal and a signaL derived from the modulation on said modulated radio frequency signal, H. second detection means at said source responsive to the output of said second means for developing as an output a signal which is proportional to the energy of the output of said second means at the carrier frequency of said modulated radio frequency signal, and I. means responsive to the output of said second detection means for varying the phase of said signal derived from said modulated radio frequency signal such that the output of said second detection means is reduced to substantially zero whereby the degree of phase variation required is a function of the two-way propagation distance of said modulated radio frequency signal.

Claim 4

The apparatus according to claim 1 wherein said first input signal is an amplitude modulated signal.

Claim 5

The apparatus according to claim 1 wherein said first input signal is a frequency modulated signal.

Claim 6

The apparatus according to claim 1, further comprising; F. means for transmitting said modulated radio frequency signal to said first means, said means including a phase stable signal generator, and G. means for generating said second input signal which means is in phase synchronization with said phase stable signal generator whereby the degree of phase variation of said second input by said means responsive to the output of said detection means is a function of the propagation distance of said modulated radio frequency signal.

Claim 7

A communication apparatus having a distance measuring capability, comprising; A. first means for transmitting a carrier radio frequency signal modulated by a first ranging tone, B. first receiver means responsive to said radio frequency signal, including means for generating a second ranging tone at the modulation frequency of said first ranging tone, and C. a product detector at said first receiver means developing an output which is the product of said radio frequency signal and said second ranging tone.

Claim 8

A communication apparatus having a distance measuring capability, comprising; A. first means for transmitting a carrier radio frequency signal modulated by a first ranging tone, B. first receiver means responsive to said radio frequency signal, including means for generating a second ranging tone at the modulation frequency of said first ranging tone, and C. a product detector at said first receiver means developing an output which is the product of said radio frequency signal and said second ranging tone.

Claim 9

The apparatus according to claim 6, further comprising; D. means sensing the energy in said output at the carrier frequency of said radio frequency signal, and E. control means responsive to said energy for changing the phase of said second ranging tone until said energy is reduced to substantially zero, whereby the phase of said second ranging tone is locked with the phase of the modulation on said modulated radio frequency signal.

Claim 10

The apparatus according to claim 7, wherein said means sensing the energy comprises a narrow band filter and an amplitude detector.

Claim 11

The apparatus according to claim 8, wherein said control means comprises a synchronous detector responsive to the output of said amplitude detector, a phase shifter and a dither generator in operative association with said synchronous detector and said phase shifter.

Claim 12

The apparatus according to claim 6, further comprising D. second means for transmitting a second carrier radio frequency signal modulated by said second ranging tone to second receiver means at said first means, and E. a product detector at said second receiver means developing an output which is the product of said radio frequency signal and said second ranging tone.

Claim 13

The apparatus according to claim 10, further comprising at each of said first and second receiver means; F. means sensing the energy in said output at the carrier frequency of said radio frequency signal, and G. control means responsive to said energy for changing the phase of said second ranging tone until said energy is reduced to substantially zero, whereby the phase of said second ranging tone is locked with the phase of the modulation on said modulated radio frequency signal.

Claim 14

The apparatus according to claim 11, wherein said means sensing the energy comprises a narrow band filter and an amplitude detector.

Claim 15

The apparatus according to claim 12, wherein said control means comprises a synchronoUs detector responsive to the output of said amplitude detector, a phase shifter and a dither generator in operative association with said synchronous detector and said phase shifter.