Abstract: A desired acoustic signal is extracted from a noisy environment by generating a signal representative of the desired signal with processor (30). Processor (30) receives aural signals from two sensors (22, 24) each at a different location. The two inputs to processor (30) are converted from analog to digital format and then submitted to a discrete Fourier transform process to generate discrete spectral signal representations. The spectral signals are delayed to provide a number of intermediate signals, each corresponding to a different spatial location relative to the two sensors. Locations of the noise source and the desired source, and the spectral content of the desired signal are determined from the intermediate signal corresponding to the noise source locations. Inverse transformation of the selected intermediate signal followed by digital to analog conversion provides an output signal representative of the desired signal with output device (90).

Abstract: An optical fiber test unit and a method of operating it. The test unit has a laser with a computer controlled excitation current input. To take a measurement, the laser is turned on for a period of time which is approximately equal to twice the propagation time through the fiber. The laser is then turned off and the reflected signal is recorded. This signal is displayed and contains discontinuities which indicate discontinuities in the fiber. The unit provides good dynamic range, but is able to make measurements more rapidly than a conventional OTDR. It is therefore well suited for scan testing of fiber optic cable bundles.

Abstract: Method and apparatus for adaptive filtering a first signal to produce a second signal that approximates a desired signal including an acoustic charge transport type programmable transversal filter (PTF) having a number of taps where each tap corresponds to an associated delayed first signal and each tap having means for providing a variable tap weight to modify the filter response. The first signal is coupled to the PTF and the output of the PTF produces the second signal. A summer compares the output of the PTF and the desired signal to produce an error signal. A programmable delay line has time delays programmable to integer multiples of the PTF tap spacing to provide a delayed version of the first signal, and a multiplier multiplies the error signal and the delayed input of the programmable delay line to produce a gradient signal.

Abstract: An electron spectroscopy system is disclosed which is specially suited for chemical analysis of electrically isolated specimens. X-rays or other ionizing radiation is focused to a relatively small spot on the surface of the electrically isolated sample to be analyzed. An electron energy analyzer has its input optics focused such that the input field of view of the electron energy analyzer is coincident with the beam spot produced by the focused beam of ionizing radiation on the specimen so as to capture secondary photoelectrons emitted from the surface of the sample under analysis. The energies of the secondary photoelectrons are analyzed to obtain a spectrum of the constituents of the surface of the sample under analysis. A flood beam of relatively low energy electrons is directed onto the surface of the sample for neutralizing the positive surface charge in the region of the beam spot.