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A passive electronic warfare system must deinterleave trains of pulses from a number of radar transmitters. An adaptive parametric channelizer for acquiring and tracking trains of pulses consists of an input channelizer operating under the control of a resource control processor. Each pulse descriptor word (PDW), a set of digitized signal parameters measured by a specialized receiver of radar pulse signals, is temporarily stored in a first-in-first out (FIFO) buffer memory. PDW data from the FIFO buffer memory is then applied to a set of parameter filter devices. These filters are provided with a range of parameter values, forming windows, by the resource control processor. The filters operate such that when a PDW falls within one of the filter's windows, a match output is asserted and applied to a match list generator which maps asserted matches into a list of filter index numbers. That list is applied to a mapper which transforms filter indices into track buffer indices in order to store a PDW that matches one filter into an associated track buffer of a set of track buffers. The combination of at least one parameter filter linked by the mapper with a track buffer form a track channel. The match list generator supplies data and event interrupts to the resource control processor which causes the parameter window of any track channel to be modified and force track channels to be merged.

A filter system permits observed data measurements for a multiplicity of radar emitters to be deinterleaved and stored in a buffer memory. A first unit of the system simultaneously compares each one of a series of parameters in the incoming data with respective ranges of parameter values, and produces an indicator of each match made. A second unit of the system assigns an hierarchial order to the indicators from the first unit, and produces from those indicators an ordered sequence of encoded outputs. A third unit of the system is a memory divided into a series of areas equal in number to the number of ranges of parameter values. Each one of the memory areas is addressed by a respective one of the encoded outputs of the second unit. The system allows data corresponding to any one of the radar emitters to be efficiently accessed for further analysis.

A method and apparatus for evaluating the similarity of multi-mode radar pulses detected by a passive ESM receiver. The method consists of fitting a straight line to the differential phase of pairs of received signals, one signal of a pair being a currently received signal pulse and the other a previously received signal pulse, by a best least squares fit method. The slope of that straight line gives the frequency offset between the signals and the mean square error between the actual phase-time data and the straight line indicates the similarity of the signals. A second measure of the similarity of the signals can be obtained by applying statistical tests for serial correlation in the difference between the phase-time data and the straight line.