Abstract: A system is described for thresholding graphics images to reduce the information content for transmission and reproduction and which uses a particular image data thresholding technique that may be used to obtain display images with a number of intensity levels. Firstly, an histogram of the image to be encoded is generated and analyzed to determine essential parameters. In particular, the background color of the image is determined by summing the histogram elements to find the median of the distribution, that is, the point at which the half sum of total pixels is reached. The extrema of the histogram are calculated and the skew is determined from the position of the median with respect thereto. If the difference between the median and the black extreme is less than half the difference between the median and the white extreme then the background of the image is deemed to be black, otherwise, the image will be defined as having a white background.

Abstract: The disclosed scanning acoustic microscope comprises a solid lens body consisting of two sections of materials having different sound propagation characteristics but matching acoustic impedances. A lens is formed by the interface of said two sections and has a focal point coinciding with the apex of a sharply pointed tip formed at the free surface of one of said sections. The tip and the specimen to be investigated are immersed in a coupling medium having a relatively high acoustic absorption coefficient. The lens body carries an acoustic transducer on its surface remote from the tip for sending plane sound waves through the lens and tip onto the specimen. Acoustic waves reflected from the specimen are also received by this transducer. Acoustic waves transmitted through the specimen optionally may be received by a transducer arranged on the opposite side of the specimen. By appropriate processing of the received signals, high-resolution (10 nm) images of the specimen can be obtained.

Abstract: A method for converting an image from a bit map to a run end or run length representation includes the steps of: storing the image as a bit map representation; accessing for each byte in an image by a look-up table a selected routine, corresponding to such byte, from a number of routines for converting bit strings to run representations, wherein the look-up table accessed is selected in accordance with a color value of a preceding pixel binary bit; and executing the selected routine on the current byte to convert the bit string to a run representation; storing in a run representation buffer, as a count value, each run representation; repeating the above steps of accessing and executing for each byte and storing for each run of continuous color to the end of the image.

Abstract: A system is shown for connecting a plurality of intelligent terminals through a central non-blocking switch to each other, to a partitioned memory and to one or more service processors to form a local area network.

Abstract: A method for trimming the resonant frequency of fabricated SAW devices. The resonant frequency of SAW devices of the type having a substrate with structures made of a second material, other than the substrate material, upon its surface, is decreased by removing quantities of the substrate material until the desired change in frequency is obtained. In one embodiment, the substrate material of the SAW device is removed by etching the substrate in a fluorocarbon plasma, which leaves the structure made of the second material substantially unchanged. In a second embodiment, the resonant frequency of SAW resonators is increased by heating the SAW device at a temperature in excess of 250.degree. C. until the desired change in resonant frequency is obtained.

Abstract: An apparatus and method for detecting the polarization of signals reflected from targets immersed in clutter. Signals reflected from targets illuminated with quasimonochromatic electromagnetic signals such as FMCW radar are received by antennas responsive to orthogonally polarized components of the reflected signals. These received orthogonal signal components are then analyzed in a processor which detects the polarization of the reflected signal by estimating the Stokes parameters for the reflected signal. The estimated Stokes parameters may then be used to generate detection criteria that are compared to a predetermined threshold level. The presence of the target is indicated when the detection criteria level exceeds the level of the predetermined threshold.

Abstract: An apparatus and method for detecting the polarization of signals reflected from targets immersed in clutter. Signals reflected from targets illuminated with quasimonochromatic electromagnetic signals such as FMCW radar are received by antennas responsive to orthogonally polarized components of the reflected signals. These received orthogonal signal components are then modified such that one component is phase shifted with respect to the other signal components, and the amplitudes of the signal components are varied according to predetermined angles of polarization. The resulting signals are further analyzed in a processor which detects the polarization of the reflected signals by estimating the Stokes parameters for the reflected signal. The Stokes parameters may then be used to generate detection criteria that are compared to a predetermined threshold level.

Abstract: An apparatus for phase matching transmission lines which generates signals with frequencies and phase characteristics that are representative of the length of the transmission line under test and alternately samples and compares these signals to minimize signal source instabilities.

Abstract: A cathode ray dual mode electromagnetic beam deflection amplifier system for providing current for driving a deflection coil, and means for switching between linear and resonant non-linear operational modes. In the linear mode, the deflection coil current is controlled to closely follow an applied input deflection sweep voltage and operates as a push-pull amplifier. In the non-linear resonant mode, one-half the output stage is abruptly decoupled from the deflection coil such that energy stored in the deflection coil is discharged into a series capacitor, the subsequent resonant pulse being returned through the non-decoupled half of the output stage to a power supply.