Abstract: An abradable material for a rub strip of a gas turbine engine component includes a polymer matrix, and an organic or inorganic filler distributed through the matrix, wherein the abradable material has a compression spring rate profile including: less than 50,000 lb/in at ?65° F., less than 35,000 lb/in at room temperature, and less than 35,000 lb/in at 200° F.

Abstract: A signal processor is described for object detection systems such as radar and sonar systems in which wave energy is transmitted and received as a train of discrete pulses of frequencies stepped in predetermined sequence. The received signal processor comprises a plurality of processing channels of number corresponding to the number of sub-pulses in the transmitted pulse train, each channel including frequency selective means such that signal returns of frequencies corresponding to but one of the transmitted sub-pulses are processed by that channel. Means are provided for simultaneously sampling the signal levels in all channels and indicating that channel in which the signal level is greatest, this sampling process being serially repeated at times related to each of the times of transmission of one sub-pulse of the train.

Abstract: An improved spatial filtering system includes a plurality of tracker modules for isolating selected signals from an array of signal data values collected from a signal environment by a plurality of receiver elements and stored in a residual signal storage element. Each tracker module includes a generating module for generating, from the array of signal data values, estimated contributions of a selected signal at each of the plurality of receiver elements. Each tracker module also includes an output signal estimation module, connected to the generating module, for determining, based on the estimated contributions, an output signal that is representative of the selected signal.

Abstract: A conversion apparatus for quantizing an initial set of weights for a weighted sum signal processing system having one or more conversion arrays. Each conversion array stores a plurality of values to be converted, quantizes the values that are to be converted to produce a set of discrete values and a set of error values, and replaces the stored values with the set of discrete values. Each conversion array combines the set of error values with a set of transformation weights to form one or more transformed error sets. The conversion apparatus further includes a transfer device for successively combining the one or more transformed error sets most recently formed with the contents of a successive conversion array. The transfer device monitors the successively produced sets of error values and halts the successive conversions and combinations when a predetermined condition is satisifed. The invention also features methods of quantizing initial sets of weight.

Abstract: A high-speed, limited-shift signal processor for quantized weighting of an input signal, which receives the input signal and delays is to provide a plurality of delay outputs and selects a number of the delay outputs to be modified by limited shifting of their place values. The limited-shift signal processor generates at least one weighted value from each delay output, including shifting the digit positions of each selected delay output to shift its place value, and sums each of the place-value-shifted delay outputs to obtain a weighted sum signal of the input signal.

Abstract: A conversion apparatus for quantizing a set of weights for a weighted sum signal processing system, including a predetermined number of conversion arrays operable in succession and a transfer and monitor circuit. Each conversion array stores a plurality of values to be converted, quantizes the values to be converted to produce a set of discrete values and a set of error values and replaces the contents of the means for storing with the set of discrete values. Each conversion array also combines the set of error values with a set of interpolator weights to form a transformed error set. The transfer and monitor circuit successively combines the transformed error set most recently formed with the contents of a successive conversion array, monitors the successively produced sets of error values, and halts the successive conversions and combinations when a predetermined condition is satisfied. The invention also features a method of quantizing such a set of weights.

Abstract: Apparatus is disclosed for reproducing transmitted information which is subject to multipath delay spread effects and doppler frequency-shift effects. The information is transmitted as a series of modulated information pulses of differing nominal frequencies. The nominal frequencies of successive pulses are repeatedly shifted through a predetermined sequence of frequencies. Arrivals of the transmitted pulses are detected at a receiver and are processed to determine the frequencies to which the transmitted pulses are doppler shifted and the multipath delays of each pulse. This frequency and delay information is then used to reproduce the transmitted information from the arrival pulses.

Abstract: A signal processor is described for pulse-echo systems such as sonar and seismographic systems in which wave energy is transmitted and received as a train of discrete pulses of different frequencies ordered in predetermined sequence. The receiver comprises a plurality of signal processing channels each of which selects one subpulse and delays it through an interval of duration inversely related to its time position in the pulse train, to thus bring the received subpulse signals into time alignment so that when added their summed amplitude constitutes the target signal output. For interference level compensation, a running estimate is made of the interference level in each of the signal processing channels, and the channel signals then are weighted by this interference estimate as an inverse function of its magnitude.