Patent ID: 8892373

Claim:
A method for determining the starting instant of a periodically oscillating signal response, wherein said signal response comprises a first set of half periods having a polarity equal to a polarity of the first half period in the signal response, and a second set of half periods having a polarity opposite to the polarity of the first half period in the signal response, said method comprising: determining, using an electronic control device, a peak half period as the half period with the highest amplitude in a selected one of said first and second sets; determining, using the electronic control device, a zero-crossing instant of said signal response occurring a known time distance from said peak half period; determining the starting instant of said signal response based on said zero-crossing instant and a relationship between said peak half period and said starting instant; wherein determining the relationship between said peak half period and said starting instant comprises: determining a ratio between an amplitude of a preceding half period and an amplitude of said peak half period, wherein said preceding half period is the half period immediately preceding said peak half period in one of said first and second sets; comparing said ratio to a threshold value; and determining the number of half periods occurring between said peak half period and the starting instant of the signal response based on said comparison.