Patents Represented by Attorney C. A. Nieves
  • Patent number: 5673044
    Abstract: The loop filter of a sigma-delta analog-to-digital converter (ADC) includes a multistage loop filter coupled to the output port of an input summer stage, for receiving difference signals therefrom. The loop filter includes a plurality of cascaded stages. All but one of the cascaded stages includes first and second cascaded half-stages, and that one of the stages includes at least one half-stage. The last one of the cascaded half-stages in the loop filter is coupled to the input port of an ADC stage for coupling loop-filtered difference signals or resonated signals thereto. The ADC stage produces the desired output digital signals. A DAC is coupled to the output of the ADC stage, for generating an analog replica of the desired digital output signals, and for coupling the replica to the input summer stage for aiding in generating the difference signals.
    Type: Grant
    Filed: January 29, 1996
    Date of Patent: September 30, 1997
    Assignee: Lockheed Martin Corporation
    Inventor: Leopold Ernest Pellon
  • Patent number: 5644673
    Abstract: An optical fiber cable includes one or more optical fibers surrounded by a dielectric longitudinal strength member such as an aramid braid. The cable penetrates a bulkhead at a connector which couples tensile forces acting on the strength member to the bulkhead, to prevent breakage of the fiber(s). The connector includes two mating annular conical members which surround the optical fibers, with the strength braid flared and extending between the mating conical surfaces. The two cones are forced together by a bulkhead connector with a first thread and a second connector with a mating thread, thereby captivating the strength member to the bulkhead to resist tension. Concentric or annular grooves are formed in at least one of the mating conical surfaces to aid in gripping the slippery strength member.
    Type: Grant
    Filed: January 16, 1996
    Date of Patent: July 1, 1997
    Assignee: Lockheed Martin Corp.
    Inventor: Richard Joseph Patterson
  • Patent number: 5630161
    Abstract: A digital signal processor (24) includes a plurality of vector processors (212x), each of which is made up of a group of, for example, six signal processors (214x). Each signal processor includes Local 1 and Local 2 ports (201, 203), and the Local 1 port of one processor of a group is coupled by a path (218) to the Local 2 port of another processor, so the group forms a ring. Each signal processor (214) also includes a memory (234), an arithmetic processor (232), and a switcher (230) for making internal interconnections among the ports, and also includes a switcher control (364, 366). At least one of the signal processors (214) of each group is of a type including a further external port (206), by which data can be coupled by a path (105) to and from the group. The signal processors of each group can be interconnected for serial or parallel processing, all under the control of a group controller (216) associated with each vector processor.
    Type: Grant
    Filed: April 24, 1995
    Date of Patent: May 13, 1997
    Assignee: Martin Marietta Corp.
    Inventors: Richard G. Branco, Edward J. Monastra, David J. Ovadia
  • Patent number: 5608400
    Abstract: A sigma-delta analog-to-digital converter (10) provides high loop gain for suppression of noise components by use of a regenerative feedback loop or resonator (50), which produces a comb resonance response 212), embedded in the main degenerative feedback loop (48). The main loop includes an ADC (32) which samples at a clock frequency, which in turn defines a Nyquist frequency. The main loop also includes a DAC (38) which has a transfer function (42), which is equalized by a filter (44). The resonator (50) includes a low-pass filter (52) which matches the equalized main loop transfer function, a DC block (56), and a null filter (54) which nulls the resonator gain at the comb peak which lies above the Nyquist frequency. The open-loop transfer function of the regenerative loop (50) is set to unity gain and 0.degree..+-.N 360.degree. phase at the frequency of the analog input signal. A multipole embodiment (510) has multiple regenerative loops (55o) which produce multipole noise rejection (642).
    Type: Grant
    Filed: August 24, 1995
    Date of Patent: March 4, 1997
    Assignee: Martin Marietta Corporation
    Inventor: Leopold E. Pellon
  • Patent number: 5602554
    Abstract: A radar system which uses an active phased-array antenna achieves improved clutter improvement factor (CIF) by powering the various transmit-receive (TR) modules of the antenna with direct voltage (DC) derived from a plurality of phases of the power-line alternating current (AC). Each TR module receives power which originates with one phase of the source AC. The phases are selected so that the modulation of the radio-frequency (RF) signals by each TR module tends to cancel in the summed signal from the array antenna.
    Type: Grant
    Filed: August 8, 1995
    Date of Patent: February 11, 1997
    Assignee: Martin Marietta Corp.
    Inventors: Bruce M. Cepas, Wilbur Lew, Eric L. Holzman, John G. Ferrante
  • Patent number: 5600326
    Abstract: Monopulse radar operation is improved by nulling a single mainlobe jammer and multiple sidelobe jammers while maintaining the angle measurement accuracy of the monopulse ratio. A sidelobe jammer cancelling adaptive array is cascaded with a mainlobe jammer canceller, imposing a mainlobe maintenance technique or constrained adaptation during the sidelobe jammer cancellation process so that results of the sidelobe jammer cancellation process do not distort the subsequent mainlobe jammer cancellation process. The sidelobe jammers and the mainlobe jammer are thus cancelled sequentially in separate processes.
    Type: Grant
    Filed: December 16, 1991
    Date of Patent: February 4, 1997
    Assignee: Martin Marietta Corp.
    Inventors: Kai-Bor Yu, David J. Murrow
  • Patent number: 5576711
    Abstract: A monopulse signal processor provides target monopulse ratios and thus target angles having an improved accuracy in those situations where a low signal-to-noise ratio subsists and the monopulse ratio is derived from a sequence of pulses. The monopulse ratio value is determined by: ##EQU1## and .SIGMA..sub.Ii is the in-phase component of the sum signal for the i.sup.th pulse, .SIGMA..sub.Qi is the quadrature component of the sum signal for the i.sup.th pulse, .DELTA..sub.Ii is the in-phase component of the difference signal for the i.sup.th pulse, and .DELTA..sub..OMEGA.i is the quadrature component of the difference signal for the i.sup.th pulse.
    Type: Grant
    Filed: October 17, 1984
    Date of Patent: November 19, 1996
    Assignee: Martin Marietta Corporation
    Inventors: Randall D. Morris, Raymond S. Berkowitz
  • Patent number: 5481234
    Abstract: The electrical length of a strip transmission line structure is adjusted by adding conductive projections from the ground planar conductors which extend in depth toward the strip conductor and in length along the strip conductor. These projections may preferably be formed by inward deformation of the ground planes at the desired locations. In strip transmission lines having the strip conductor positioned between two ground planes, projections are preferably added in aligned pairs with each ground plane providing one of the projections of the pair.
    Type: Grant
    Filed: December 19, 1983
    Date of Patent: January 2, 1996
    Assignee: Martin Marietta Corp.
    Inventors: Norman R. Landry, Edward J. Kent
  • Patent number: 5481270
    Abstract: A method and apparatus for identifying a remote target includes a transmitter for transmitting pulses of energy toward the target for generating echo signals, and a receiver for receiving the echo signals, and for generating received signals representing the target, noise and clutter. The received signals are applied through a plurality of cascaded channels, each including a Doppler filter cascaded with a multiplier, each also including range sidelobe suppression, for, in each of the cascaded channels, narrowband filtering the signals passing therethrough about a controllable center frequency, and for, if necessary, converting the signals passing therethrough to baseband, for thereby applying one of a plurality of Doppler filtered baseband signals to the input of each of the range sidelobe suppressors of each of the cascaded channels. The power of the Doppler filtered baseband signals in each range bin is evaluated for determining the frequency at which the spectral density is greatest.
    Type: Grant
    Filed: March 4, 1994
    Date of Patent: January 2, 1996
    Assignee: Martin Marietta Corporation
    Inventors: Harry Urkowitz, Nicholas J. Bucci, Jerome E. Freedman
  • Patent number: 5459474
    Abstract: An active array antenna, which may be used for radar, includes antenna elements (antelements) supported in a two-dimensional array. The fronts of the elements are protected by a cover. In order to allow easy repair, each column of antelements is associated with a slide-in carrier which simultaneously mates with all antelements of a column. Each carrier has a transmit-receive (TR) module for each antelement with which it mates, and a column beamformer. Each carrier also has logic modules and power supplies for the TR modules. The total width of each slide-in carrier with its TR modules, beamformer, logic and power supplies, is less than or equal to the column-to-column spacing. Each carrier can be slid out from the rear to expose all the active components for each column of antelements, so maintenance can be performed without environmental exposure.
    Type: Grant
    Filed: March 22, 1994
    Date of Patent: October 17, 1995
    Assignee: Martin Marietta Corporation
    Inventors: Joseph A. Mattioli, Ashok K. Agrawal, Norman R. Landry
  • Patent number: 5451962
    Abstract: A capacitance multiplier/regulator (FIG. 1) stores charge at high voltage across a capacitor (22,32), and capacitance-multiplies current to a load (100) by step-down transformers (26,36), controlled switches (24,34), and rectifiers (28,38). The switch pairs (24a,24b;34a,34b) each switch in antiphase, but the switching phase between the pairs is controlled (FIG. 5) in a feedback manner to controllably generate a voltage across a transformer primary winding (14.sub.p), which couples a feedback-controlled alternating voltage across secondary winding (14.sub.s). The alternating voltage is added to the unregulated voltage by a rectifier (18,20), so the bus voltage is controllably greater than the unregulated input voltage. The feedback controls either the bus voltage or the load voltage. Stress on the switches is reduced by preventing capacitor recharge during a load pulse.
    Type: Grant
    Filed: August 26, 1994
    Date of Patent: September 19, 1995
    Assignee: Martin Marietta Corporation
    Inventor: Robert L. Steigerwald
  • Patent number: 5440311
    Abstract: A radar transmits dispersed pulses in which the subpulses are modulated by first and second mutually complementary code sequences, the autocorrelation functions of which are selected so that, in the sum of their autocorrelation functions, the main range lobes add, and the range sidelobes cancel. The received pulses with their Doppler sidebands are applied to a plurality of channels, each of which (except one) contains a mixer-oscillator combination that removes a specific Doppler phase shift along the range dimension at a different channel frequency. One channel has no mixer-oscillator because it is centered at a zero channel frequency. Within each channel, the received signals modulated by the first and second codes are matched-filtered by filters matched to the first and second codes, respectively, to produce first and second time-compressed pulses, each including (a) a main lobe representing the target range, and (b) undesirable range sidelobes.
    Type: Grant
    Filed: August 6, 1993
    Date of Patent: August 8, 1995
    Assignee: Martin Marietta Corporation
    Inventors: John J. Gallagher, Harry Urkowitz
  • Patent number: 5414428
    Abstract: A radar system transmits dispersed pulses, and receives echoes from targets. The echo signals are digitized and applied over a number of signal paths. In each signal path except one, the digitized signal is multiplied by one of a plurality of differential exponential signals, for converting the echo signal of different exponential signals, for converting the echo signal in each path to baseband, with the baseband frequency representing a particular Doppler which depends upon the exponential signal. In the one remaining signal path, no multiplier is used, and the echo signal is deemed to be at baseband. The signals in each path are applied through a cascade of a pulse compressor and a range sidelobe suppressor. Since Doppler filtering has not yet taken place, full compression and range sidelobe reduction is not achieved, because of extraneous pulse-to-pulse phase shifts.
    Type: Grant
    Filed: May 6, 1994
    Date of Patent: May 9, 1995
    Assignee: Martin Marietta Corp.
    Inventors: John J. Gallagher, Harry Urkowitz
  • Patent number: 5402130
    Abstract: In a monopulse radar processor, the usual sum (s) and difference (d) signals are manipulated to produce two other signals (s+ad and s+bd, in which a and b are constants). The phase of each of these derived signals with respect to the sum signal is then determined. The real part of d/s and, if desired, the imaginary part of d/s are calculated from these measured phase angles. The real part of d/s is the conventional output from a monopulse processor.
    Type: Grant
    Filed: May 28, 1981
    Date of Patent: March 28, 1995
    Assignee: Martin Marietta Corporation
    Inventor: Samuel M. Sherman
  • Patent number: 5392042
    Abstract: A sigma-delta (.SIGMA..DELTA.) analog-to-digital converter (ADC) accepts band-limited analog signals, and subtracts an analog replica of an output pulse- or amplitude-density modulated (ADM) signal therefrom to produce an error signal. The error signal is processed by an analog filter or resonator with a nondelayed forward path and a tapped nonaccumulating delay line, and summed feedback and feedforward weights coupled to the taps, to thereby produce a resonated signal. An ADC processes the resonated signal, and produces the ADM signal. The ADC undesirably produces quantization noise. A digital-to-analog converter (DAC) noiselessly converts the PDM signal into the analog replica, to aid in forming the error signal. In a particular embodiment of the invention, the resonator includes a recursive analog transversal filter with delays and linear weighting elements for linearity and high operating speed. The ADC may be in a high-speed system such as a radar.
    Type: Grant
    Filed: August 5, 1993
    Date of Patent: February 21, 1995
    Assignee: Martin Marietta Corporation
    Inventor: Leopold E. Pellon
  • Patent number: 5376939
    Abstract: A radar system simultaneously transmits first and second signals toward a target at higher and lower carrier frequencies, respectively. Each carrier is phase-modulated by a set of pulses. The first set of pulses is dispersed in time, and the second set of pulses is mutually complementary thereto. The transmitted pulses are reflected by the target and received simultaneously. The received signals are processed separately by Doppler filtering. Each Doppler-filtered return is code-matched filtered, and the filtered signals in each Doppler channel are summed with the corresponding Doppler-and-code-matched-filtered signals originating from the other transmitted frequency, to form range signals. Each range signal has its main lobe enhanced and its sidelobes suppressed by the summing of the code-matched-filtered mutually complementary echoes.
    Type: Grant
    Filed: June 21, 1993
    Date of Patent: December 27, 1994
    Assignee: Martin Marietta Corporation
    Inventor: Harry Urkowitz
  • Patent number: 5377090
    Abstract: A distributed power system for providing multiple output voltages, including pulsed voltages, to a solid-state phased-array radar transmit/receive module, for example, includes: an energy-storage capacitor for coupling to an input dc power source and for storing substantial energy at high voltage for supplying pulsed voltages at low voltage; at least one capacitance-multiplying converter, including first and second transformers with multiple secondary windings, for producing positive and negative voltages on buses internal to a power module; and a plurality of series regulators to obtain multiple positive and negative load voltages, including pulsed voltages, from the positive and negative bus voltages. Substantial energy storage is achieved within the power module; and, if even more energy storage is desired, an additional external energy-storage capacitor can be coupled to the input power leads, thereby being coupled in parallel with the energy-storage capacitor.
    Type: Grant
    Filed: January 19, 1993
    Date of Patent: December 27, 1994
    Assignee: Martin Marietta Corporation
    Inventor: Robert L. Steigerwald
  • Patent number: 5371506
    Abstract: An improvement in monopulse radar achieves nulling of multiple mainlobe jammers while maintaining the angle measurement accuracy of the monopulse ratio by using multiple simultaneous beams, thereby obtaining the additional degrees of freedom necessary for cancelling more than one mainlobe jammer (MLJ). The beams are placed one null beamwidth apart in order to maintain orthogonality. The MLJs are nulled in the orthogonal direction of the angle estimate giving undistorted monopulse ratios.
    Type: Grant
    Filed: July 19, 1993
    Date of Patent: December 6, 1994
    Assignee: General Electric Co.
    Inventors: Kai-Bor Yu, David J. Murrow
  • Patent number: 5361249
    Abstract: A fault tolerant communication arrangement, for switching parallel N-bit information among a plurality of stations, includes an M-bit crossbar switch, where M is greater than N by a number S of supernumerary or spare bit paths. At each station, an interface unit monitors for errors, and when an error is identified to a bit in the transmission path, routes the defective bit to one of the spare bit paths. All stations reroute data from the defective bit path to the same spare bit path. Error coding information is generated at the transmitting interface unit, and transmitted over some of the supernumerary bit paths, and when the number of defective bit paths reduces the number of available supernumerary bit paths to zero, the bit intensity of the error coding is reduced, to free additional supernumerary paths. In a system in which some of the stations include memory, a failure of a memory bit at a particular address is, in effect, a failure of that bit in an overall transmission path.
    Type: Grant
    Filed: October 26, 1993
    Date of Patent: November 1, 1994
    Assignee: Martin Marietta Corp.
    Inventors: Edward J. Monastra, Leon Trevito, Richard G. Branco
  • Patent number: 5343211
    Abstract: An antenna subject to standoff sidelobe barrage jamming exhibits a null in its sidelobe structure at a selectable elevation angle for all azimuth angles of interest. The null can be set to the elevation angles corresponding to the angle of the standoff jammers. The null is generated with the aid of an interferometer associated with each column of the antenna array. The interferometer produces a pattern having a plurality of lobes. The interferometer pattern is phased and amplitude adjusted relative to the antenna pattern of its associated column line array so that subtraction of the patterns causes one or more sidelobe of the antenna pattern to be at least partially canceled. An azimuth beamformer combines the elevation patterns of a plurality of column arrays, each connected to its own interferometer, to produce a pencil beam with a sidelobe structure exhibiting a null at the particular elevation angle.
    Type: Grant
    Filed: January 22, 1991
    Date of Patent: August 30, 1994
    Assignee: General Electric Co.
    Inventor: Michael A. Kott