Patents by Inventor Javad Ashjaee

Javad Ashjaee 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).

  • Patent number: 6463091
    Abstract: A receiver of a radio frequency signal having a pseudo-random noise (PRN) code, and techniques of processing such a signal that are especially adapted for ranging applications. A signal corresponding to the PRN code is locally generated and used for decoding the received signal in a manner to reduce ranging errors that can result when multipath (delayed) versions of the radio frequency signal are also present. A significant application of the receiver and signal processing techniques of the present invention is in a Global Positioning System (GPS), wherein a number of such signals from several satellites are simultaneously received and processed in order to obtain information of the position, movement, or the like, of the receiver. A delay locked loop (DLL) correlator, provided in each of the receiver's multiple processing channels, locks onto a line of sight signal from one of the satellites with the effect of any multipath signal(s) being significantly reduced.
    Type: Grant
    Filed: May 23, 2000
    Date of Patent: October 8, 2002
    Assignee: Magellan Corporation
    Inventors: Mark Zhodzicshsky, Victor Veitsel, Stanislov Sila-Novatisky, Javad Ashjaee, Lionel Garin
  • Patent number: 6456233
    Abstract: The measurements of two GPS and/or GLONASS receivers are related to a common time moment by extrapolating measurement data that has arrived through a connection link with a delay. This common time moment is defined by the user. Cycle slips in the phase-lock loops (PLLs) of the receivers, which may be caused by blockage of direct signals from the satellites, strong interference signals, and reflections, are deflected and corrected in a multi-loop nonlinear tracking system. The procedure of resolution of phase measurement ambiguities comprises the preliminary estimation of floating ambiguities by a recurrent (e.g., iterative) procedure including the simultaneous processing of code and phase measurements for all satellites for each processing time interval, and the gradual improvement of the result as the information is accumulated. After the resolution of ambiguity, the user coordinates are estimated with centimeter accuracy on the basis of phase measurements on the carrier frequency.
    Type: Grant
    Filed: June 5, 2001
    Date of Patent: September 24, 2002
    Assignee: Topcon GPS LLC
    Inventors: Mark Isaakovich Zhodzishky, Victor Abramovich Veitsel, Michail Y. Vorobiev, Javad Ashjaee
  • Publication number: 20020021241
    Abstract: Satellites of the GPS and GLONASS navigation systems broadcast code signals which are modulated onto respective carrier signals, and which are received by two receivers on Earth. The first receiver is situated at a point with known coordinates. The results of its measurements are transmitted to a user at a second receiver through a connection link, the user being interested in knowing his or her positioning. The second receiver is similar to the first receiver and it receives the signals of the same satellites. By processing data from the measurements of code delays and carrier phase shifts in the satellite signals received by two receivers, the methods and apparatuses of the inventions of the present application determine the location of the user with high precision and make the time indications of receiver clocks more accurate and exact.
    Type: Application
    Filed: June 5, 2001
    Publication date: February 21, 2002
    Inventors: Mark Isaakovich Zhodzishky, Victor Abramovich Veitsel, Michail Y. Vorobiev, Javad Ashjaee
  • Publication number: 20020011004
    Abstract: Disclosed are electronic plumb indicators for monopoles, survey poles, global positioning antennas and the like. A exemplary plumb indicator comprises a substrate, a plumb bob suspended by a thread (e.g., wire, cable, string, etc.) and disposed over a first surface of the substrate, and a probe. The substrate has an array of conductive pads disposed over its first surface, preferably in a regular pattern. The probe has a first body portion held by the plumb bob but allowed to move freely in the vertical direction, and a conductive tip disposed between the plumb bob and the first surface of the substrate. The probe tip makes contact with the first surface of the substrate, and contacts one or more pads in normal operation. The pads may be scanned electronically to determine the location of the probe tip and plumb bob with respect to the substrate.
    Type: Application
    Filed: April 20, 2001
    Publication date: January 31, 2002
    Inventor: Javad Ashjaee
  • Patent number: 6337657
    Abstract: Disclosed are methods and apparatuses for generating the estimates of receiver's coordinates and/or time offset for a moment of time tn without large errors caused by short-term shading of a part of the observable global positioning satellites and also without large dynamic errors caused by the receiver movement. The receiver may be stationary or mobile (i.e., rovering). A set of snapshot-solution values for the position coordinates and time offset of the receiver at the time moment tn, and a set of predicted values for the position coordinates and time offset of the receiver at the time moment tn are generated. The accuracy of each of these sets are determined, and a set of refined estimates for the position and time offset of the receiver is generated based the snapshot solution values, the predicted position values, and the accuracies.
    Type: Grant
    Filed: March 9, 2000
    Date of Patent: January 8, 2002
    Assignee: Topcon Positioning Systems, Inc.
    Inventors: Mark I. Zhodzishsky, Peter P. Zagnetov, Javad Ashjaee
  • Patent number: 6313789
    Abstract: Disclosed are methods for increasing the fail-safety characteristics of tracking systems for navigation receivers which receive signals from many satellites. In an exemplary embodiment of the present invention, an individual PLL circuit is used to track the phase of each satellite's carrier signal, and a vector common tracking loop is used to track the disturbances of the carrier phases which are caused by one or more common sources, such as the movement of the receiver's antenna(s) and/or the phase fluctuation of the receiver's main reference oscillator. The vector common tracking loop uses phase information from all of the satellites being tracked, and for this reason can be made more wide-band than each of the individual PLL circuits. The wider bandwidth of the vector common tracking loop provides higher dynamic properties and more safe tracking when faint and weakening satellite signals are present.
    Type: Grant
    Filed: June 10, 1999
    Date of Patent: November 6, 2001
    Assignee: Topcon Positioning Systems, Inc.
    Inventors: Mark Zhodzishsky, Javad Ashjaee
  • Patent number: 6278407
    Abstract: Choke-ring ground planes are commonly used for multipath rejection in geodetic surveying systems. Such ground planes consist of a thick metal disc with deep grooves on one of the flat surfaces. An antenna is mounted in the center of the grooved surface. Known ground planes used in dual frequency communication systems (L1 and L2) could not be constructed to have good rejection of multipath signals in both L1 and L2 frequencies; instead, they are constructed for good rejection of multipath signals in L2 but not good for the rejection of multipath signals in L1. A first invention provides for equally good multipath rejection for both L1 and L2 frequencies by incorporating novel electromagnetic filter structures within the choke-ring grooves. The filter structures of the present invention enable the choke ring to provide multipath rejection in each frequency band which is as good as, or better than, the multipath rejection achieved in the L2 band with existing devices.
    Type: Grant
    Filed: February 23, 1999
    Date of Patent: August 21, 2001
    Assignee: Topcon Positioning Systems, Inc.
    Inventors: Javad Ashjaee, Vladimir S. Filippov, Dmitry V. Tatarnikov, Andrej V. Astakhov, Igor V. Sutjagin
  • Patent number: 6268824
    Abstract: Satellites of the GPS and GLONASS navigation systems broadcast code signals which are modulated onto respective carrier signals, and which are received by two receivers on Earth. The first receiver is situated at a point with known coordinates. The results of its measurements are transmitted to a user at a second receiver through a connection link, the user being interested in knowing his or her positioning. The second receiver is similar to the first receiver and it receives the signals of the same satellites. By processing data from the measurements of code delays and carrier phase shifts in the satellite signals received by two receivers, the methods and apparatuses of the inventions of the present application determine the location of the user with high precision and make the time indications of receiver clocks more accurate and exact.
    Type: Grant
    Filed: September 18, 1999
    Date of Patent: July 31, 2001
    Assignee: Topcon Positioning Systems, Inc.
    Inventors: Mark Isaakovich Zhodzishky, Victor Abramovich Veitsel, Michail Y. Vorobiev, Javad Ashjaee
  • Patent number: 6219376
    Abstract: Method of suppression of narrow-band interferences attending at the receiver input added to the useful broadband signal and noise. There is a disclosed compensator rejecting narrow-band interferences by means of adjustment loops. Two general methods of construction of such loops are considered. The first general method is based on filtration of the in-phase and quadrature components of the error vector—difference of the interference vector and compensating vector. The second method is based on filtration of the amplitude and full phase of the interference signal. Automatic tuning of the compensator to the mean frequency and effective interference band is ensured.
    Type: Grant
    Filed: February 21, 1998
    Date of Patent: April 17, 2001
    Assignee: Topcon Positioning Systems, Inc.
    Inventors: Mark I. Zhodzishsky, Michail Y. Vorobiev, Victor A. Prasolov, Javad Ashjaee
  • Patent number: 5953367
    Abstract: A receiver of a radio frequency signal having a pseudo-random noise (PRN) code, and techniques of processing such a signal that are especially adapted for ranging applications. A signal corresponding to the PRN code is locally generated and used for decoding the received signal in a manner to reduce ranging errors that can result when multipath (delayed) versions of the radio frequency signal are also present. A significant application of the receiver and signal processing techniques of the present invention is in a Global Positioning System (GPS), wherein a number of such signals from several satellites are simultaneously received and processed in order to obtain information of the position, movement, or the like, of the receiver. A delay locked loop (DLL) correlator, provided in each of the receiver's multiple processing channels, locks onto a line of sight signal from one of the satellites with the effect of any multipath signal(s) being significantly reduced.
    Type: Grant
    Filed: August 9, 1995
    Date of Patent: September 14, 1999
    Assignee: Magellan Corporation
    Inventors: Mark Zhodzicshsky, Victor Veitsel, Stanislov Sila-Novatisky, Javad Ashjaee, Lionel Garin
  • Patent number: 5769370
    Abstract: A knocked-down portable geodetic surveying station in kit form is disclosed which utilizes a GPS antenna attached to the top portion of a surveyor's stake, or other type monopole. By positioning the bottom portion of the monopole directly upon a desired ground location, and adjusting the angular position of the monopole so that it is precisely vertical, the GPS antenna may be quickly and accurately positioned level and directly above the desired ground location. The GPS antenna and monopole are designed to be used in conjunction with a newly designed geodetic surveying tripod which can be quickly and conveniently set up to support the monopole in its vertical position directly above the desired ground location.
    Type: Grant
    Filed: May 8, 1996
    Date of Patent: June 23, 1998
    Assignee: Javad Positioning, LLC
    Inventor: Javad Ashjaee
  • Patent number: 5749549
    Abstract: A portable geodetic surveying station is disclosed which utilizes a GPS antenna attached to the top portion of a surveyor's stake, or other type monopod. By positioning the bottom portion of the monopod directly upon a desired ground location, and adjusting the angular position of the monopod so that it is precisely vertical, the GPS antenna may be quickly and accurately positioned level and directly above the desired ground location. Additionally, because the monopod has a known, fixed length, the height of the GPS antenna above the desired ground location will always be a constant, and will not vary from one survey point to the next. The GPS antenna and monopod are designed to be used in conjunction with a newly designed geodetic surveying tripod which can be quickly and conveniently set up to support the monopod in its vertical position directly above the desired ground location.
    Type: Grant
    Filed: December 29, 1995
    Date of Patent: May 12, 1998
    Assignee: Javad Positioning, LLC
    Inventor: Javad Ashjaee
  • Patent number: 4928106
    Abstract: A global positioning system (GPS) receiver having a common radio frequency section and a separate digital signal processing channel for each of a plurality of satellite signals which are simultaneously being received and processed by the receiver in order to calculate the position, velocity or other desired parameters of the receiver. The radio frequency section receives and processes both of the standard satellite signals on different frequency L1 and L2 carriers in order to provide the multi-channel digital section signals from which the relative phase of the carriers from each of the plurality of satellites may be determined. Particular mutually coherent local oscillator and digital clock frequencies are selected in order to minimize the complexity of the receiver without creating any undesired side effects.
    Type: Grant
    Filed: July 14, 1988
    Date of Patent: May 22, 1990
    Assignee: Ashtech Telesis, Inc.
    Inventors: Javad Ashjaee, Roger J. Helkey, Robert G. Lorenz, Robert A. Sutherland