Abstract: 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.

Abstract: A digital quadrature demodulator for an intermediate frequency (IF) input signal with an analog-to-digital (A/D) converter having a sampling frequency f.sub.s and an input to which the IF input signal is applied where the IF input signal has a bandwith B<f.sub.s /4 centered about a frequency of f.sub.s /4. The demodulator includes an arrangement to direct even numbered output signals from the A/D converter to an inphase channel and odd numbered output signals from the A/D converter to a quadrature channel where each channel contains a highpass filter and the demodulator includes circuits to decimate by 4 signals of the channels to generate, together with the filters, a quadrature output signal Q(nT) at an output of the quadrature channel and an inphase output signal I(nT) at an output of the inphase channel. The quadrature highpass filter in the quadrature channel has an optimized transform architecture in which the filter coefficients h.sub.

Abstract: 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.

Abstract: 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.

Abstract: The disclosure teaches a reconfigurable parameter filter of the type useful in radar ESM systems. The filter has first and second sections adapted to be supplied with first and second binary numbers, respectively. Each section consists of upper and lower limit storage registers and upper and lower limit comparators, the comparators being coupled to an AND gate and responsive to the respective binary number to enable the AND gate if the value of the signal lies within the window set by the storage registers. The two sections can operate on two independent data words or can be coupled to act as a unit on one data word under the control of a mode selecting circuit. As a result the same standardized circuit module can process either one high precision parameter number or two low precision parameter numbers.