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System for sensing velocity through the use of altimetry signals

  • US 4,106,017 A
  • Filed: 06/01/1976
  • Issued: 08/08/1978
  • Est. Priority Date: 06/01/1976
  • Status: Expired due to Term
First Claim
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1. A system for determining the relative velocity of two objects in a direction substantially transverse to a line between them comprising, in combination:

  • transmitting means provided on a first of said objects for illuminating the second of said objects with periodic pulses of wave energy;

    receiving means also provided on said first object for receiving and detecting pulses reflected from said second object, said receiving means being adapted to receive reflected energy at a pair of phase center locations spaced apart in said transverse direction;

    amplitude correlating means for comparing the amplitude characteristics of each reflected pulse received at a first of said phase center locations with the amplitude characteristics of the reflected pulse received at the other of said phase center locations N pulse repetition intervals earlier in time, said amplitude characteristics being dependent upon the spatial position of each phase center at a time determined by a pulse transmit time and a pulse sample time, said pulse sample time being the time at which the amplitude sample is taken, where the spatial position of the phase center can be modified by modifying the pulse transmit and pulse sample time, said correlating means generating an output signal indicating the degree of correlation between said pulses as determined by the results of said comparisons wherein said correlating means includes means for generating a correlation output signal representing the error in alignment between the spatial position of said first phase center location and the spatial position of said other phase center location N pulse repetition intervals earlier in time;

    control means to adjust the pulse transmit and pulse sample time of said first phase center relative to the transmit time of the said other phase center location N pulses earlier in time, said adjustment being determined by the level of said output signal controlling a variable frequency oscillator to modify the pulse repetition frequency of said transmitting means; and

    means for determining said relative velocity based on the quotient of said phase-center separation distance and N multiplied by said pulse repetition interval.

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