Patent ID: 8407020

Claim:
A method for determining frequency and slope of a linear frequency modulated signal for implementation on a computer comprising the steps of: collecting windowed data samples concerning the signal; formulating a search surface function from said windowed data samples; dividing the search surface function into a number of parts; calculating the search surface function values at a selected number of frequency and slope values, said selected number of frequency and slope values being related to the number of parts; calculating search surface function parts for each search surface data part at the selected frequency and slope values; interpolating the search surface function parts at values between selected frequency values for a selected slope to obtain first interpolated values, each interpolation between selected frequency values being an interpolation geometry; calculating a correlation coefficient for each interpolation geometry; determining the best interpolation geometry for the search surface function part at slopes between selected frequencies and selected slopes as the interpolation geometry that gives the highest correlation coefficient; interpolating to obtain search surface function part values at frequencies and slopes between selected frequencies and slopes according to the determined best interpolation geometry to obtain second interpolated values; adding the search surface function parts together to give a restored search surface function, said search surface parts having first interpolated values and second interpolated values incorporated therein; searching through frequency and slope values of said search surface function calculated values, first interpolated values, and second interpolated values to obtain the frequency and slope values that maximize the search surface function; and providing the frequency and slope values that maximize the search surface function as the frequency and slope of the signal.