TABLE OF CONTENTS ELINT analysis often involves interleaved pulse trains. This means that several pulsed signals are present and that successive pulses may not come from the same emitter. The first problem the analyst faces, then, is to separate the interleaved pulses into groups of pulses from the same emitter. This process is called deinterleaving. The first step is usually to make use of information derived form individual pulses, often referred to as pulse descriptor words (PDWs). PDWs consist of parametric information such as pulse duration (PD), pulse amplitude (PA), pulse radio frequency (RF), angle of arrival (AOA), and time of arrival (TOA). Other on-pulse parameters such as descriptions of intrapulse modulation and polarization may also be available. If fine frequency measurements are made, the RF parameter may be thought of as the frequency of arrival (FOA) because the RF originally transmitted has been altered by the Doppler shift due to relative motion of the ELINT collector and the emitter.
In many cases, deinterleaving can be accomplished using single pulse parameters as reported in the PDWs. This is also called pulse sorting. If there is no frequency agility, RF is a very useful first sort. AOA is a very useful sorting parameter because it is determined by the emitter s location and not by its signal design. If there are no reflected signals to cause confusion, a constant AOA will be present over rather long periods of time even when the platforms are moving. To have the same AOA,...
