Abstract: Range measurements useful for determining a device's position are screened to eliminate unacceptable measurements. A two-stage range measurement screening technique involves a coarse screening stage that includes comparing the range measurement to an estimated expected range and a fine screening stage that includes comparing the range measurement to the computed fading-average range. Range measurements that fall within both coarse and fine screening windows are deemed acceptable and are supplied to a position tracking filter together with their estimated measurement accuracies. Range measurements that do not fall within either the coarse or fine screening window are discarded and do not corrupt the position solution. The accuracies of acceptable range measurements are determined from multiple factors including the measurement offset from a fading-average of previous range measurements and the standard deviation of the previous range measurements.

Abstract: Range measurements useful for determining a device's position are screened to eliminate unacceptable measurements. A two-stage range measurement screening technique involves a coarse screening stage that includes comparing the range measurement to an estimated expected range and a fine screening stage that includes comparing the range measurement to the computed fading-average range. Range measurements that fall within both coarse and fine screening windows are deemed acceptable and are supplied to a position tracking filter together with their estimated measurement accuracies. Range measurements that do not fall within either the coarse or fine screening window are discarded and do not corrupt the position solution. The accuracies of acceptable range measurements are determined from multiple factors including the measurement offset from a fading-average of previous range measurements and the standard deviation of the previous range measurements.