Patents by Inventor Donald C. D. Chang

Donald C. D. Chang has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20120326925
    Abstract: An advanced multiple-beam GPS receiving system is achieved that is capable of simultaneously tracking multiple GPS satellites independently, detecting multiple interference signals individually, and suppressing directional gain in the antenna pattern of each beam in the interference directions. The GPS receiving system can be used for both planar and non-planar receiving arrays, including arrays that are conformally applied to the surface of a platform such as an aircraft. The GPS receiver combines spatial filtering and acquisition code correlation for enhanced rejection of interfering sources. Enhanced gain in the direction of GPS satellites and the ability to shape the beam patterns to suppress gain in the direction of interfering sources make the GPS receiving system largely insensitive to interfering and jamming signals that plague conventional GPS receivers.
    Type: Application
    Filed: July 16, 2012
    Publication date: December 27, 2012
    Applicant: SPATIAL DIGITAL SYSTEMS
    Inventor: Donald C. D. Chang
  • Publication number: 20120328036
    Abstract: A system is provided that enhances the throughput and reliability of wireless communications by providing multi-beam user terminals that exhibit directional discrimination. Multiple wireless communication channels are matched with multiple beams created from an array antenna by a beam-forming processor. The multiple wireless communication channels are bonded into a single virtual channel, thereby increasing data bandwidth while reducing interference and multi-path effects that can degrade communications. The beam-forming function may be performed in a dedicated beam-forming processor or may reside within a general-purpose microprocessor located in the user terminal. In addition, a wireless communications system with access points featuring multiple beams that exhibit directional discrimination that can concurrently support multiple users with multi-beam terminals via a common frequency channel.
    Type: Application
    Filed: October 17, 2011
    Publication date: December 27, 2012
    Applicant: SPATIAL DIGITAL SYSTEMS
    Inventor: Donald C. D. Chang
  • Publication number: 20120319772
    Abstract: This invention aims to present a smart and dynamic power amplifier module that features both power combining and power sharing capabilities. The proposed flexible power amplifier (PA) module consists of a pre-processor, N PAs, and a post-processor. The pre-processor is an M-to-N wavefront (WF) multiplexer (muxer), while the post processor is a N-to-M WF de-multiplexer (demuxer), where N?M?2. Multiple independent signals can be concurrently amplified by a proposed multi-channel PA module with a fixed total power output, while individual signal channel outputs feature different power intensities with no signal couplings among the individual signals. In addition to basic configurations, some modules can be configured to feature both functions of parallel power amplifiers and also as M-to-M switches. Other programmable features include configurations of power combining and power redistribution functions with a prescribed amplitude and phase distributions, as well as high power PA with a linearizer.
    Type: Application
    Filed: July 12, 2011
    Publication date: December 20, 2012
    Applicant: SPATIAL DIGITAL SYSTEMS
    Inventor: Donald C. D. Chang
  • Publication number: 20120319885
    Abstract: A system for processing data streams or signals includes a wave-front multiplexer configured to process first and second input signals into first and second output signals each carrying information associated with the first and second input signals, a first processing unit configured to process a third input signal carrying information associated with the first output signal into a third output signal, a second processing unit configured to process a fourth input signal carrying information associated with the second output signal into a fourth output signal, and a wave-front demultiplexer configured to process fifth and sixth input signals into fifth and sixth output signals each carrying information associated with the fifth and sixth input signals. The fifth input signal carries information associated with the third output signal, and the sixth input signal carries information associated with the fourth output signal.
    Type: Application
    Filed: June 17, 2012
    Publication date: December 20, 2012
    Applicant: Spatial Digital Systems
    Inventor: Donald C. D. Chang
  • Publication number: 20120301136
    Abstract: A communication system and method that allows a transmitter segment (ground end of uplink segment) to dynamically combine power from a plurality of propagation channels (transponders) to improve power levels of signals being transmitted, without affecting the receiver segment (user end of downlink segment) and the propagation segment (space segment), and without modifying propagation apparatus configurations (satellite). Specifically, the transmitter segment generates mixtures of input signals by using Wavefront-Multiplexing and transmits wavefront-multiplexed (WFM) signals through propagation channels to a receiver segment that coherently separates the mixtures of received WFM signals by using adaptive equalization and Wavefront-De-Multiplexing.
    Type: Application
    Filed: November 23, 2011
    Publication date: November 29, 2012
    Applicant: SPATIAL DIGITAL SYSTEMS
    Inventor: Donald C. D. Chang
  • Publication number: 20120274499
    Abstract: The proposed MIMO radar imaging method takes advantages of measurement techniques of spatial frequency components of an RF area image from radar returns. To minimize size, weight and power (SW&P), minimum redundancy arrays (MRAs) for both Tx and Rx with unique geometries are proposed. MIMO waveforms are utilized to index the radiated illuminations to a targeted area in the forms of 1-D spatial frequency components. Consequently, the corresponding radar returns from the targeted field of view (FOV) are captured by the Rx MRA. With the knowledge of uniquely designed MRA array geometries, virtual beams are synthesized in Rx processor; usually one Tx and many contiguous Rx fan beams. These virtual beams may be dynamically “moved” to different beam positions. The elongated beam direction for Tx fan beam and that for Rx fan beams are perpendicular to one another. Thus intersections of the Tx fan-beam and many Rx fan-beams are the very areas of radar returns. We refer those areas as virtual beam crosses.
    Type: Application
    Filed: April 29, 2011
    Publication date: November 1, 2012
    Applicant: SPATIAL DIGITAL SYSTEMS
    Inventor: Donald C. D. Chang
  • Publication number: 20120243581
    Abstract: An advanced digital beam forming technique is achieved that is capable of simultaneously forming multiple beams and attenuating the cross-pol component at multiple locations. The proposed invention, comprising a series of signal inputs, optimization loops and weighting processes, successfully eliminates the side effect of an increase of the cross-pol in the process of beam-forming, thus reducing potential interference. This technique utilizes the orthogonally polarized signal component which is already available and can minimize both the horizontally polarized and vertically polarized cross-pol at the same time. The complexity of computation can be reduced by using only part of the orthogonal polarized components in the optimization.
    Type: Application
    Filed: March 24, 2011
    Publication date: September 27, 2012
    Inventors: FRANK LU, DONALD C. D. CHANG, YULAN SUN
  • Publication number: 20120212371
    Abstract: A receive only smart antenna with a command pointing option for communicating with geostationary satellites that autonomously detects the directions from which desired signal are received, and steer the multiple beams accordingly. An array feed is used to illuminate a parabolic reflector. Each feed element of the receive only smart antenna is associated with a unique beam pointing direction. As a receiver is switched to different feed elements, the far-field beam is scanned, making it possible to track a geostationary satellite in a slightly inclined orbit. This eliminates the need for mechanical tracking and maintains high antenna gain in the direction of the geostationary satellite. The receive only smart antenna also features capabilities to form multiple simultaneous beams supporting operations of multiple geo-satellites in closely spaced slightly inclined orbits. The designs can support orthogonal beams for enhanced bandwidth capacity via multiple beams with excellent spatial isolation.
    Type: Application
    Filed: February 9, 2011
    Publication date: August 23, 2012
    Applicant: Spatial Digital Systems
    Inventor: Donald C. D. Chang
  • Publication number: 20120183295
    Abstract: A novel terrestrial wireless communications technique for terrestrial portable terminals including hand-held mobile devices and fixed wireless instruments, utilizing a spoke-and-hub communications system, having a plurality of individual hubs and/or base-stations all in communications with the portable terminals. The portable terminals and the hubs are assigned to use incompatible polarity formats in terms of circularly polarity (CP) and linearly polarity (LP). In forward links, a signal processed by the LP ground telecommunications hubs is radiated through multiple antennas with various LP polarities to an individual CP user simultaneously. The multiple paths are organized via assignments of a plurality of polarities, frequency slots, and directions by wavefront multiplexing/demultiplexing techniques such that the same communications assets including frequency spectrum may be re-used by other users. The same polarity diversity methods can be extended to peer-to-peer communications.
    Type: Application
    Filed: September 13, 2011
    Publication date: July 19, 2012
    Applicant: SPATIAL DIGITAL SYSTEMS
    Inventor: Donald C. D. Chang
  • Patent number: 8223733
    Abstract: A mobile wireless communications system including a plurality of individual transponding nodes of various types, all in communication with a central processing hub. A local user signal is processed by the central processing hub and radiated through multiple paths to a plurality of the plurality of individual transponding platforms simultaneously. The signal is then re-radiated by each of the plurality of the plurality of individual transponding platforms to a mobile terminal that receives the re-radiated signal from the plurality of the plurality of individual transponding platforms coherently and in phase. The number of transponders and codes used to transmit each user signal can be readily adapted to user requirements.
    Type: Grant
    Filed: February 2, 2005
    Date of Patent: July 17, 2012
    Assignee: The DIRECTV Group, Inc.
    Inventors: Kar W. Yung, Frank A. Hagen, Donald C. D. Chang
  • Publication number: 20120140780
    Abstract: A communication system and method for a deep space spacecraft receiver to perform post-processing to dynamically combine received signal power coherently for pre-processed signal streams radiated non-coherently from a distributed, multiple element, Ka-band transmitting array via multiple concurrent propagation paths. Mutually orthogonal data and pilot signals travel though the multiple propagation paths. A pre-processor utilizing wavefront multiplexing restructures signal streams on the ground into multi-channel wavefrom structures along with injections of pilot signals for diagnostic and probing purposes. These restructured, or “wavefront multiplexed” (WFM) signals are transmitted through propagation channels to a receiver on the spacecraft, wherein adaptive equalization and wavefront de-multiplexing coherently separates the mixtures of received WFM signals.
    Type: Application
    Filed: February 6, 2012
    Publication date: June 7, 2012
    Inventor: DONALD C. D. CHANG
  • Publication number: 20120069918
    Abstract: The present invention features novel methods of implementing configurable arrays for personal portable devices including hand-held mobile devices and re-locatable wireless devices, utilizing a wireless communications system that employs multiple individual hubs and/or base-stations. The digital beam forming (DBF) methodology utilizes multiple low gain elements conformal to the mechanical contours of handheld devices to function as arrays. The distributed N element arrays dynamically provide the options of reconfigurable shaped beams with near hemispheric radiation patterns for various handheld orientations and conditions by various users, while also supporting operations of multiple orthogonal beams concurrently connecting to multiple hubs. The larger the N becomes, the more flexibility the residing devices can provide.
    Type: Application
    Filed: September 19, 2011
    Publication date: March 22, 2012
    Applicant: SPATIAL DIGITAL SYSTEMS
    Inventor: Donald C. D. Chang
  • Publication number: 20120063550
    Abstract: A receiver with orthogonal beam forming technique is achieved that is capable of differentiating different signal components within the received composite signal. An adaptive processor is used to eliminate the signal component whose phase information is known or can be calculated. The phase information of the major component of a signal can be easily acquired by using a limiter. The phase information of other signal components can be acquired by their direction information and other characteristics, such as modulation scheme, etc. Multiple orthogonal beams can be formed by eliminating one unwanted signal component each time by the adaptive processor until all unwanted signal is eliminated. Thus, a composite signal from multiple sources can be broken down into their component signals.
    Type: Application
    Filed: November 22, 2010
    Publication date: March 15, 2012
    Inventors: Donald C. D. Chang, Yulan Sun, Frank Lu
  • Publication number: 20120062404
    Abstract: A novel noise injection technique is presented to improve dynamic range with low resolution and low speed analog to digital converters. This technique combines incoming signal and noise signal with wave front de-multiplexer and split into several channels. Then low resolution and low speed analog to digital converters are used to sample each channels. All signals are recovered using wave front multiplexer. For advanced design, ground diagnostic signals with optimizing processor can be added to guarantee recovery quality.
    Type: Application
    Filed: January 5, 2011
    Publication date: March 15, 2012
    Inventors: Tzer-Hso Lin, Yuanchang Liu, Donald C.D. Chang
  • Publication number: 20120062420
    Abstract: This device combines multiple elements that function like a single smart antenna that performs both connectivity and spatial discrimination functions. The antenna functions in both receive and transmit modes. The apparatus utilizes commonly used components to distinguish and separate desired satellite signals from those signals of satellites in close directional proximity. Disclosed are six methods for optimizing simultaneously reception of multiple desired satellite signals performed either mechanically or electronically and also included is an optimization technique. The transmission apparatus uses many of the same components as the receiver antenna and additionally uses in-beam nulling to fine tune transmission.
    Type: Application
    Filed: February 16, 2011
    Publication date: March 15, 2012
    Inventor: Donald C. D. Chang
  • Publication number: 20120064759
    Abstract: A retractable mobile device power module comprises of a plug to power outlet, a retractable power cord, an adapter, and a retractor. With this design, power supply for mobile devices can be compact and low profile. Besides providing power, this design can be used for data transmission as well.
    Type: Application
    Filed: November 22, 2010
    Publication date: March 15, 2012
    Applicant: SPATIAL DIGITAL SYSTEMS
    Inventors: Yuanchang Liu, Donald C. D. Chang, Derrick Chu
  • Publication number: 20120063542
    Abstract: A novel wide null forming system achieves both wide bandwidth and beam width null through employing an antenna array to receive and transmit signals to which a complex null weight vector, calculated by perturbation program, is applied. The novel wide null forming system includes a multiple-element antenna array for receiving or transmitting signals. Multiple conditioning units matching the number of elements is present to condition the signals for proper reception and analysis, after which a series of complex multiplier processors adds complex weights. After being weighted each constituent beam is combined in an adding processor to form one composite beam for use by the user.
    Type: Application
    Filed: November 22, 2010
    Publication date: March 15, 2012
    Inventors: Yuanchang Liu, Yulan Sun, Donald C. D. Chang
  • Publication number: 20120057716
    Abstract: A quiet zone generation technique for acoustic/audio signals is proposed for mitigation of selected noise or interferences over limited areas in free space by injecting the very acoustic noise, interference, or audio feedback signals via iterative processing, generating quiet zones dynamically. This creates undesired noise-free quiet zones. Optimization loops operating iteratively to electronically process cancellation signals consist of three interconnected functional blocks: (1) an acoustic injection array, consisting of pick-up arrays to obtain the interference signals, beam forming networks for element weighting and/or re-positioning, and array elements for noise injections, (2) a diagnostic network with strategically located probes, and (3) an optimization processor with cost minimization algorithms to calculate element weights for updating.
    Type: Application
    Filed: January 18, 2011
    Publication date: March 8, 2012
    Inventors: Donald C. D. Chang, Steve Chen
  • Publication number: 20120058729
    Abstract: A quiet zone generation technique is proposed for interference mitigation for a receive antenna by injecting the very interference signals via iterative processing, generating quiet zones dynamically for receive (RCV) antennas. The receive antenna may feature multiple receiving apertures distributed over a finite area. Optimization loops consist of four cascaded functional blocks; (1) a pick-up array to obtain the interference signals, (2) element weighting and/or repositioning processors, (3) an auxiliary transmit (XMIT) array with optimized element positions, (4) a diagnostic network with strategically located probes, and (5) an optimization processor with cost minimization algorithms. To minimize interferences between transmit (Tx) and receiving (Rx) apertures in limited space of an antenna farm for communications and/or radar applications are very tough problems. Among the tools for solving the problems are many conventional techniques listed in the references [1,2,3].
    Type: Application
    Filed: September 2, 2010
    Publication date: March 8, 2012
    Inventors: DONALD C. D. CHANG, MICHAEL T. H. LIN, STEVE CHEN
  • Publication number: 20120051284
    Abstract: A satellite broadcasting system is achieved where remote beam forming processors combined with wavefront multiplexers located among distributed ground stations are used to control downlink beam footprints and pointing directions. Digital beam forming (DBF) techniques allow a single satellite download broadcast antenna array to generate multiple independently pointed simultaneous downlinks, which may contain distinct information content. Allocation of some uplink back-channel elements as diagnostic signals allows for continuous calibration of uplink channels, improving downlink broadcast array and user broadcast performance. Wavefront multiplexing/demultiplexing allows all array element signals to be radiated by the broadcasting antenna array, with simultaneous propagation from ground stations to the broadcasting satellites through available parallel propagation channels in the uplinks of feeder links, with equalized amplitude and phase differentials.
    Type: Application
    Filed: November 8, 2011
    Publication date: March 1, 2012
    Applicant: SPATIAL DIGITAL SYSTEMS
    Inventor: Donald C. D. Chang