For every range gate ( \ tau _ s ) and for every pulse cycle ( T _ s ), the so-called I and Q voltages are derived taking the real and imaginary part of the complex voltage given in ( ) : Their expressions are:
12.
In every range gate the FFT algorithm is applied to the serie of N _ f IQ signals, where N _ f is the number of FFT points used in the FFT . The result of the FFT is a complex spectrum S _ { compl } ( k ) where k is the Doppler frequency.
13.
At 8 : 40 pm ( 12 : 40 pm EST ) on 25 February 1991, parts of an Iraqi Patriot air defense system in tracking the Scud missile over Dhahran was provoked by a shift in the range gate of the radar, due to the continuous use of the software for more than 100 hours without resetting.
