Abstract: A recursive digital filter and method for filtering an n-bit digital input signal. The filter includes a summing circuit which receives an input signal. A second summing circuit is also provided which is coupled to the first summing circuit. Further provided is a feedback circuit which is operable to allow the first and second summing circuits to generate a filtered output signal without using a multiplier.

Abstract: A virtual image display including an image hologram, a dispersion compensating hologram for providing playback illumination to the image hologram, and an illumination source for providing playback illumination to the dispersion compensating hologram.

Abstract: Transmitter for transmitting communication traffic via phase modulated carrier signals. The device provides for an efficient amplification of a phase modulated carrier signal using Class C amplifier technology. An envelope function is applied to the carrier signal by modulating the Class C amplifier with a related spectrum-suppressing amplitude envelope signal. Phase distortion accompanying the amplitude modulation of the Class C amplifier is compensated by generating a phase offset for the carrier signal. As each envelope function for suppressing the spectrum is generated, a corresponding phase offset may be applied to the carrier signal, avoiding the consequences of phase shift resulting from amplitude modulating the carrier signal in the Class C amplifier.

Abstract: The conventional sintered, thin hydrogen negative electrode of a nickel-hydrogen storage cell or the like is replaced by a thicker porous electrode having a greater volume to receive water produced at the negative electrode during discharge of the cell. As a result, the dilution of the electrolyte within the negative electrode is less as compared with the thinner electrode, so that the freezing point depression of the electrolyte within the negative electrode is maintained. Freezing of the electrolyte and reduced performance of the cell are thereby avoided. To maintain the low weight of the electrode and reduce its cost even though its thickness is increased, platinum particles are replaced by conductive particles upon which platinum has been deposited.

Abstract: A communications receiver for a code division multiple access (CDMA) satellite communication system in which a plurality of data carriers share the same band. A pilot carrier transmits a timing reference used by all receivers to acquire the clock used in timing the code generators, and used as a frequency and phase reference for data detection. This receiver employs a digital signal processor that detects a spread pilot carrier and uses the phase noise on the pilot carrier to subtract the communication link phase noise from the data carriers, thus allowing communication at lower signal-to-noise ratios.

Abstract: A method for use with a vehicle simulator which provides for the rapid update of displayed terrain data in areas of non-visible terrain surfaces and terrain image discontinuities. The method is for use with a system which projects a time-varying computer-generated image scene representative of the terrain as viewed from a moving vehicle. The image scene is derived from a digital data base stored in slow speed secondary memory. The method includes the steps of predicting, by means of line-of-sight sampling ray, which segments of the data base could be visible after a predetermined time interval. The data base is accessed for the predicted segments of data and these segments are retrieved therefrom. The data segments designated are then stored in predetermined memory locations in high-speed main memory. Finally, selected ones of the stored segments are displayed based on the actual vehicle path and position after the predetermined time interval has elapsed.

Abstract: A method for achieving satellite (24) attitude stabilization against the undesired influences of solar pressure or other attitude disturbances to be used with earth-orbiting satellites of the type employing two solar collection panels (30a), (30b) extending from the satellite body in generally opposite directions (36), (38). Synchronized simultaneous movement of both solar panels about their normal sun-tracking position causes desirable torques to be generated which have a cancelling influence on the undesired satellite movement caused by solar pressure or other attitude disturbances.

Abstract: A modular direct radiating antenna system for producing highly contoured beam patterns is disclosed. The system comprises a plurality of array modules, each having a number of radiation elements. An intramodule feed network is provided to communicate RF energy between a module port and the radiation elements in an equal-power, equal-phase relationship. A second feed network, an intermodule feed network, is provided to communicate RF energy between an antenna system port and the respective module ports. The second feed network is adapted to couple the power and adjust the electrical path lengths so that the RF power communicate between the respective module ports and the system port is of predetermined relative amplitudes and phases. The intermodule excitation power and phase distribution across the entire planar array aperture produces the desired contoured beam to encompass a required area.

Abstract: According to the invention, a high-speed digital data communication system employs current mode circuitry as input and output devices at the ends of a transmission line, such as the interconnections between integrated circuit chips. Specifically, a current mode driver switch generates output current amplitudes responsive to a source of a digital signal representative of data to be transmitted. The switch output is connected to the input of a transmission line. The output of the transmission line is connected to the input of a receiving circuit that responds to the current amplitudes and has an input at an approximately constant voltage level. The receiving circuit is a transistor connected in a common base configuration. The emitter of the transistor is connected to the output of the transmission line. The base of the transistor is connected to a constant voltage source. A pulse shaper in the form of a Schmitt trigger has positive feedback from output to input.

Abstract: A method of fabricating a polarizing dish antenna reflector (10) wherein a light source (22) is employed to pyrolyze an organometallic compound (14) disposed on the antenna surface to form grid elements (24) directly thereon. The surface of the parabolic dish antenna reflector (10) is coated with an organometallic compound (14) that comprises a metallic component such as gold, silver, copper chrome, or other suitable metal. The coated surface may be conditioned by depositing a surface film of polyimide, or the like. The coated surface is then pyrolyzed by using a high intensity focussed light source (22), such as a laser or discharge lamp to form metal grid lines (24) on the surface. The light source (22) is scanned across the surface to create parallel scan lines, or the light source may be fixed and the reflector surface can be moved relative to the light source (22) using a computer controlled XY table (16), or the like.

Abstract: A transparent eyelevel stoplight for vehicles is disclosed, which operates on an upconversion principle wherein red light in an otherwise transparent crystal is excited by invisible infrared radiation. The crystal may take the form of a transparent plate or an optical fiber applied to the vehicle rear window. The host crystal material is doped with a suitable rare-earth ion, which when illuminated by infrared energy produces visible light. An infrared laser may be used to illuminate the doped crystal, and is activated by the vehicle brakes. The crystal material is transparent to ordinary visible light and therefore will not obscure the driver's vision.

Abstract: A cell bypass circuit is disclosed which includes a diode 32 connected electrically in parallel with a cell 20 of a battery 12. A thermal switch 34 is mounted in thermal contact with a diode 32. A relay 38 including a coil 36 and a contact 40 is provided. The coil 36 is connected to the thermal switch 34 so as to be activated by the activation thereof. The contact 40 of the relay 38 is connected in parallel with the cell 20 so that the activation of the diode 32 causes thermal energy to radiate therefrom activating the thermal switch 34. The activation of the thermal switch 34 causes the activation of the relay 38 which in turn places an electrical short across the defective cell 20 via the contacts 40 thereof.

Abstract: An antenna system includes an array of microstrip antenna elements wherein each of the elements includes two or more radiators. Electromagnetic signals are coupled from an input terminal of each element via one or more circulators which allow for application of an input signal to a first of the radiators followed by rerouting of respective signals to the next radiator. The radiators are turned to radiate at successively higher portions of the electromagnetic spectrum. By virtue of reflections of higher frequency radiation from a radiator tuned to a lower portion of the signal spectrum, each radiator radiates only that portion of the signal spectrum falling within the bandwidth of the radiator. By using three radiators, each antenna element is capable of radiating a signal spectrum three times as wide as are the bandwidths of a single radiator. Included within the antenna system is one or more power dividers to form one or more beams of radiation.

Abstract: The process comprises the testing of an electrical component during transit from a pickup position to its attachment position. The process may be accomplished by the use of a component test chuck (30) which has four pivoted arms (66, 68, 70, 72), each carrying a finger (90, 92, 94, 96). The fingers are sized and positioned for engaging on and retaining an electrical component. Two of the fingers have tips (102, 104) which are electrically conductive and are connected to a test unit (106) so that the component (93) can be tested in transit between the pickup point and the placement point.

Abstract: An inexpensive broadband dynamic IR target with a fast response time, good spatial resolution, and adequate dynamic range is disclosed. The IR target is made by coating a thin photo-conductive film on a transparent insulator. The emissivity of the film-substrate block is changed by irradiating the block with a visible image of the desired IR image. The image temperature varies from the block temperature T by an amount related to the photo-conductivity produced change in the emissivity.

Abstract: Multiple pupils (16, 18) are formed in a projection display by employment of a field lens (14) which has at least first and second interleaved Fresnel lens segments. The first set of segments has the equivalent surface of a first lens (34) and the second set of interleaved segments has the equivalent curvature of a second lens (36), with the segments being shaped to produce two exit pupils. More exit pupils, up to four without loss of resolution, can be provided by the interleaving of further lens shapes. A separate lens face (30) controls the other dimension of the exit pupils. The additional lens face may be a Fresnel lens on the opposite side of the same lens element.

Abstract: A method and apparatus for forming a multiple exposure hologram includes an object beam cut out mask 24 and reference beam cut out mask 60. Different segments of the masks are left uncovered during each exposure step and operate to shape the reference 18 and object 16 beams so that they illuminate selected areas of the photosensitive plate 12. The angle of incidence of the object beam 16 remains constant during each exposure step while the reference beam 18 illuminates the plate 12 at different angles during each exposure step. During playback, a plurality of lamps 94-106 project reconstruction beams at the hologram 12 to individually or collectively render the holographic segments viewable with a minimum of crosstalk between each segment. In the preferred embodiment, the reference beam mask includes diamond-shaped cut outs 62-74 which are selectively used with associated object beam mask cut outs 28-40 to generate a hologram in the form of a seven-segment display.

Abstract: A beam-forming network (98) employs one or a plurality of first transmission delay lines (168, 170, 172, 174) for receiving transmit signals (T1-T4) applied thereto, and a plurality of second transmission lines (176), which serve as line summers. Each of the first transmission delay lines has first and second portions (168a, 168b; 170a, 170b; 172a, 172b; 174a, 174b) spaced apart from one another so as to define first and second levels displaced from one another. The set of second transmission lines (176) are arranged in first and second subsets (176a, 176b) which are respectively disposed adjacent to the first and second levels and respectively associated with the first and second portions of the first lines, such that the first subset of second lines is coupled to the first portion of the first lines, and the second subset of the second lines is coupled to the second portion of the first lines.

Abstract: The method and system for reducing phase error of phased array radar beam steering controllers having digitally controlled phase shifters includes the monitoring of individual digitally controlled phase shifter elements, determining an additive phase correction to reduce the number of failed phase shifter elements, determining whether said additive phase correction is achievable by comparing the stuck bit state at each said failed changers element with said additive phase correction and adjusting the phase commands to the nearest values which can be achieved if the additive phase correction is unachievable.

Abstract: A noise test set for analyzing the presence of phase noise in a radar signal. A delay line discriminator using a fiber optic cable and laser light modulated by the radar signal are used. Both direct and indirect modulation techniques are disclosed, together with techniques for generating and injecting a calibration signal.