×

Location method for a elective call receiver operating in a satellite communication system

  • US 6,052,561 A
  • Filed: 02/23/1998
  • Issued: 04/18/2000
  • Est. Priority Date: 02/23/1998
  • Status: Expired due to Term
First Claim
Patent Images

1. In a communication system in which orbiting satellites illuminate portions of the earth with beams of RF energy, each beam being activated during an assigned frame and transmitting information identifying its frame number and a reference delivery area, a method for a selective call receiver to estimate its home position, comprising:

  • a) receiving and storing information received from multiple beams, including information identifying each beam'"'"'s frame number and reference delivery area wherein the step of receiving is turned off after receiving data of interest included in a received frame and then turned on again at a turn-on time preceding the expected receipt of a next frame, and wherein the time of arrival of a given beam is measured by measuring a time difference between the turn-on time and receipt of the given beam;

    b) determining a home region in which the selective call receiver is likely located, based at least in part on the information stored in step a);

    c) determining a travel time to the selective call receiver of at least one beam from each of multiple satellites and measuring the times of arrival at the selective call receiver of beams received from at least one pair of satellites (beam pairs) and, for each beam pair, calculating a real DTOA (Differential Time of Arrival) that corresponds to a difference between measured times of arrival of beams in the beam pair; and

    d) selecting, from within the home region, an estimated home position that is consistent with the travel times determined in step c).

View all claims
  • 4 Assignments
Timeline View
Assignment View
    ×
    ×