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Method and system for monitoring vehicle location

  • US 4,939,522 A
  • Filed: 05/15/1989
  • Issued: 07/03/1990
  • Est. Priority Date: 05/15/1989
  • Status: Expired due to Fees
First Claim
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1. A method for locating mobile objects within a predetermined search space, said method comprising:

  • transmitting at least two reference transmissions from spaced-apart locations, each transmission including (1) an omnidirectional initialization signal followed by (2) a positioning signal having a sweeping null;

    each said mobile object receiving the reference transmissions and measuring elapsed time between detection of the initialization signal and detection of the null in the positioning signal, said elapsed time corresponding to the relative angle between the location of the transmission and the object; and

    determining the position of each object based on comparison of each said relative angle.

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