Patent ID: 7333051
Filing Date: 2008-02-19
Classification: G01R,G01S

Abstract:
1. A method for determining whether a transmitted, pulsed signal is a linear or non-linear frequency modulated (FM) signal comprising: (a) detecting a start frequency of a first component of a pulse of a signal; (b) determining an upper reference frequency and a lower reference frequency based on the start frequency; (c) detecting a second frequency of a second component of the pulse; (d) determining an initial, upper bound reference slope based on the upper reference frequency and the second frequency; (e) determining an initial, lower bound reference slope based on the lower reference frequency and the second frequency; (f) detecting a next frequency component of the pulse; (g) determining a next, upper bound slope based on the detected, next frequency component and the upper reference frequency; (h) determining a next lower bound slope based on the detected, next frequency component and the lower reference frequency; (i) comparing the so determined next upper bound slope with a previous or initial upper bound reference slope; (j) comparing the so determined next lower bound slope with a previous or initial lower bound reference slope; (k) designating the so determined next upper bound slope as a new upper bound reference slope when the next upper bound slope is greater than the previous or initial upper bound reference slope; (l) designating the next lower bound slope as a new lower bound reference slope when the next lower bound slope is less than the previous or initial lower bound reference slope; (m) detecting an end frequency of a last component of the pulse; (n) determining a true slope based on the start and end frequencies; (o) comparing the true slope to a last designated upper bound reference slope and to a last designated lower bound reference slope; and (p) determining whether the signal comprises a linear FM signal based on the comparison of the true slope to the last designated upper and lower bound reference slopes.