By Changing Frequency Patents (Class 342/18)
  • Patent number: 10082580
    Abstract: According to some embodiments of the present invention there is provided a method for detecting locations of navigation interfering devices. The method comprises an action of receiving multiple navigation signal parameter datasets, each from one of multiple satellite signal receivers. The method comprises an action of detecting one or more interference event data according to an interference analysis of at least some of the datasets. The method comprises an action of updating a probability value for each of multiple suspected navigation interference device locations, by a location analysis of the interference event data, where each of the probability values is indicative of a likelihood that the interference event data originates from some of the suspected navigation interference device locations. The method comprises an action of selecting a subset of the suspected navigation interference device locations according to the probability values and outputting the subset.
    Type: Grant
    Filed: February 15, 2016
    Date of Patent: September 25, 2018
    Assignee: Ariel Scientific Innovations Ltd.
    Inventors: Boaz Ben-Moshe, Roy Yozevitch
  • Patent number: 9952311
    Abstract: A radar apparatus and method of reducing interference which can reduce an amount of interference are provided. The radar apparatus transmits a modulated pulse signal and a non-modulated pulse signal. The radar apparatus includes an interference frequency detecting module and a map generating module. The interference frequency detecting module detects an interference frequency that is a frequency of an interference wave, based on reception signals containing a reflection wave caused by either one of the modulated pulse signal and the non-modulated pulse signal. The map generating module generates a frequency map for specifying an interference band that is a frequency band where the interference frequency exists and a no-interference band that is a frequency band where the interference frequency does not exist. A central frequency of at least one of the modulated pulse signal and the non-modulated pulse signal is set based on the frequency map.
    Type: Grant
    Filed: February 4, 2014
    Date of Patent: April 24, 2018
    Assignee: Furuno Electric Co., Ltd.
    Inventor: Tatsuya Kojima
  • Patent number: 9366750
    Abstract: A method and apparatus for: receiving a radio frequency (RF) signal on a first channel; determining a radio signal strength of the RF signal; performing a correlation of the RF signal with a predetermined sequence of a wireless data packet to determine whether the RF signal contains the predetermined sequence; in response to the RF signal not containing the predetermined sequence, generating an indication that the RF signal is not a wireless data packet; and determining whether the radio signal strength of the RF signal exceeds a predetermined threshold. In response to i) the radio signal strength exceeding the predetermined threshold and ii) the indication being generated: measuring a parameter associated with the RF signal; determining whether the RF signal is a radar signal based on the parameter; and changing from the first channel in response to the RF signal being determined to be a radar signal.
    Type: Grant
    Filed: April 16, 2010
    Date of Patent: June 14, 2016
    Assignee: Marvell World Trade LTD.
    Inventors: Bhaskar V. Nallapureddy, Tsunglun Yu, Yungping Hsu, Sek Kin Neng
  • Patent number: 9223009
    Abstract: An auxiliary receiver implemented method of providing to a host RF system one or more frequency and bandwidth recommendation for a minimal electromagnetic interference (EMI) near-future transmission, the method including the steps of receiving signals on an antenna such as an omni-directional antenna in a band of operation of the host system 360 degrees in azimuth; analyzing the received signals in the auxiliary receiver; performing a statistical analysis in the auxiliary receiver to predict the one or more frequency and bandwidth recommendation for a minimal EMI near-future transmission; and providing one or more frequency and bandwidth recommendations to the host system.
    Type: Grant
    Filed: December 19, 2011
    Date of Patent: December 29, 2015
    Assignee: Lockheed Martin Corporation
    Inventors: Richard Wasiewicz, Peter H. Stockmann
  • Patent number: 9094057
    Abstract: Exemplary embodiments are directed to a device include a parasitic coil for protection of the device. A device may include a first circuit configured to receive a first transmitted signal at an operational frequency. The device may also include a second circuit a second circuit configured to generate a field that opposes at least one of an undesirable portion of a wireless power field of the first transmitted signal and a portion of another wireless power field proximate the first circuit, the another wireless power field generated by a second transmitted signal at a non-operational frequency of the first circuit.
    Type: Grant
    Filed: March 2, 2011
    Date of Patent: July 28, 2015
    Assignee: QUALCOMM Incorporated
    Inventors: Zhen Ning Low, Charles E. Wheatley, III, Sergio P. Estrada
  • Patent number: 9037435
    Abstract: In embodiments, a device is illustrated for determining a sample rate difference between a first information signal and a second information signal including an offset determiner for determining for each of a plurality of segments of the first information signal, associated offset values which temporally align the plurality of segments with respect to the second information signal and a calculator for calculating the sample rate difference on the basis of the offset values.
    Type: Grant
    Filed: December 22, 2011
    Date of Patent: May 19, 2015
    Assignee: OPTICOM DIPL.-ING. MICHAEL KEYHL GMBH
    Inventors: Christian Schmidmer, Roland Bitto, Michael Keyhl
  • Patent number: 9035824
    Abstract: A system and method of radar location comprises radar signal emission means, an emitted pulse of duration T1 and index i starting at instant T2(i); means receiving reflected radar signals; means determining correlation between reconstruction of an emitted pulse and signal received during the time interval between T2(i)+2*T1 and T2(i+1). The means determining a correlation can reconstruct a set, of at least one truncated pulse j of duration T3(j), less than T1, corresponding to the final part of said emitted pulse, said truncated pulses having increasing respective durations, determining at least one first correlated signal j by correlation of said truncated pulse j and signal received during time interval between T2(i)+T1 and T2(i)+T1+T3(j) and determining a second signal, based on first correlated signals j, by copying the time interval, of said correlated signal j, between T2(i)+T1+T3(j) and T2(i)+T1+T3(j+1), onto the time interval, of said second signal, between T2(i)+T1+T3(j) and T2(i)+T1+T3(j+1).
    Type: Grant
    Filed: February 22, 2013
    Date of Patent: May 19, 2015
    Assignee: Thales
    Inventors: St├ęphane Kemkemian, Jean-Paul Artis, Jean-Michel Quellec
  • Publication number: 20140354464
    Abstract: A method of preventing the jamming of radars is provided utilizing two radars located at a distance to prevent both velocity and range pull off.
    Type: Application
    Filed: May 20, 2013
    Publication date: December 4, 2014
    Inventors: Faran Awais Butt, Ijaz Haider Naqvi, Ali Imran Najam
  • Patent number: 8880016
    Abstract: An anti-jamming system includes a tunable negative jamming signal feedback loop for feedback suppression of a received jamming signal. The system includes a zero IF phase locked loop (PLL) jamming signal receiver having a synchronous demodulator and a phase detector. A VCO is included in the PLL, as well as a phase detector and a loop filter. A replica jamming signal generator includes a tracking modulator with a baseband signal input coupled to an output of a synchronous demodulator in the receiver and a carrier input provided by the VCO. An output of the tracking modulator is negatively fed back to the input of the receiver to suppress the jamming signal in the received input.
    Type: Grant
    Filed: November 17, 2012
    Date of Patent: November 4, 2014
    Assignee: Semiconductor Ideas to the Market (ITOM) B.V.
    Inventor: Wolfdietrich Georg Kasperkovitz
  • Patent number: 8823389
    Abstract: A method for identifying EMI sources in a system having a plurality of electrical components connected together by cables wherein each set of two electrical components connected by a cable forms a potential EMI source. A plurality of antennas are positioned around the vehicle and the EMI from each antenna is measured over a plurality of frequencies and the frequencies having an EMI greater than a predetermined threshold and a measurement profile of the received EMI versus the antennas for each of the identified frequencies is created. EMI reception is then simulated for each potential EMI source and a simulation profile of the received EMI versus the antennas is plotted for each potential EMI source. The actual source of the EMI is then identified by comparing the measurement profile with the simulation profile for the potential EMI sources at each frequency to determine a match of the profiles.
    Type: Grant
    Filed: August 29, 2012
    Date of Patent: September 2, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Masayoshi Takahashi, Hua Zeng
  • Patent number: 8559865
    Abstract: A method and apparatus for detecting a jammer comprising sampling an input signal; downconverting and sampling the input signal to generate a sampled downconverted (SD) input signal; comparing the sampled input signal to a wideband threshold THWB, and comparing the SD input signal to a narrowband threshold THNB; generating a wideband (WB) interrupt signal based on the comparison to the THWB, and generating a narrowband (NB) interrupt signal based on the comparison to the THNB; and generating a composite interrupt signal based on at least one of WB interrupt signal and NB interrupt signal. In one aspect, the apparatus comprises a wideband jammer detector for generating a WB interrupt signal to indicate a wideband jammer; a narrowband jammer detector for generating a NB interrupt signal to indicate a narrowband jammer; and interrupt logic for generating a composite interrupt signal based on one of WB interrupt signal and NB interrupt signal.
    Type: Grant
    Filed: July 23, 2009
    Date of Patent: October 15, 2013
    Assignee: QUALCOMM Incorporated
    Inventors: Haim M. Weissman, Avigdor Brillant, Susanta Sengupta
  • Publication number: 20130234878
    Abstract: A system and method of radar location comprises radar signal emission means, an emitted pulse of duration T1 and index i starting at instant T2(i); means receiving reflected radar signals; means determining correlation between reconstruction of an emitted pulse and signal received during the time interval between T2(i)+2*T1 and T2(i+1). The means determining a correlation can reconstruct a set, of at least one truncated pulse j of duration T3(j), less than T1, corresponding to the final part of said emitted pulse, said truncated pulses having increasing respective durations, determining at least one first correlated signal j by correlation of said truncated pulse j and signal received during time interval between T2(i)+T1 and T2(i)+T1+T3(j) and determining a second signal, based on first correlated signals j, by copying the time interval, of said correlated signal j, between T2(i)+T1+T3(j) and T2(i)+T1+T3(j+1), onto the time interval, of said second signal, between T2(i)+T1+T3(j) and T2(i)+T1+T3(j+1).
    Type: Application
    Filed: February 22, 2013
    Publication date: September 12, 2013
    Applicant: THALES
    Inventors: St├ęphane Kemkemian, Jean-Paul Artis, Jean-Michel Quellec
  • Patent number: 8350745
    Abstract: Anti jamming system comprising a tunable negative jamming signal feedback loop for feedback suppression of a received jamming signal, including an receiver receiving an jamming signal followed by a replica jamming signal generator for generating an replica jamming signal. The receiver comprising a zero IF PLL receiver having a synchronous demodulator and a phase detector, signal inputs thereof being coupled to said input means and carrier inputs coupled to in-phase and phase quadrature oscillator outputs, respectively, of a local voltage controlled oscillator (VCO), said VCO receiving a tuning control signal for tuning the zero IF PLL receiver at the carrier frequency of the jamming signal. The VCO is included in a phase locked loop (PLL) comprising subsequent to the VCO, said phase detector and a loop filter.
    Type: Grant
    Filed: October 9, 2008
    Date of Patent: January 8, 2013
    Assignee: Semiconductor Ideas to the Market (ITOM) B.V.
    Inventors: Wolfdietrich Georg Kasperkovitz, Harry Barend Schoonheijm
  • Patent number: 8350746
    Abstract: Anti jamming system comprising a tunable negative jamming signal feedback loop for feedback suppression of a received jamming signal, including a receiver receiving an jamming signal followed by a jamming signal replica generator for generating an replica jamming signal. The receiver comprising a zero IF PLL jamming signal receiver having a synchronous demodulator and a phase detector, signal inputs thereof being coupled to said input means and carrier inputs coupled to in-phase and phase quadrature oscillator outputs, respectively, of a local voltage controlled oscillator (VCO), said VCO receiving a tuning control signal for tuning the zero IF PLL jamming signal receiver at the carrier frequency of the jamming signal. The VCO is included in a phase locked loop (PLL) comprising subsequent to the VCO, said phase detector and a loop filter.
    Type: Grant
    Filed: October 10, 2008
    Date of Patent: January 8, 2013
    Assignee: Semiconductor Ideas to the Market (ITOM) B.V.
    Inventor: Wolfdietrich Georg Kasperkovitz
  • Publication number: 20100085233
    Abstract: The invention relates to a frequency-modulated radar system for detecting the surroundings with compensation of interfering effects, the compensation being achieved by varying one of the following sizes: a) temporal distance between the transmitted frequency ramps and temporal gap, respectively, between the frequency ramps, b) time from the start of the transmission ramp to the beginning of the scanning of the receiving signal, c) frequency at the start of the transmitted frequency ramp, and d) sign of the slope of the frequency ramps.
    Type: Application
    Filed: October 5, 2007
    Publication date: April 8, 2010
    Applicant: ADC Automotive Distance Control Systems GmbH
    Inventors: Markus Wintermantel, Hansjerg Goelz
  • Patent number: 7184493
    Abstract: Disclosed is a real-time pulse sorting apparatus of a preprocessor in a pulsed radiation detection system. The apparatus, responsive to digital signals generated by a system receiver, uses the instantaneous frequency as the address input to store discrete data groups in main memory. Each data group, comprising the digital data corresponding to a single analog-to-digital converter sample point, includes the RF signal amplitude, inter-channel phase difference, instantaneous frequency as well as a unique pulse number generated by the pulse sorting apparatus. The present invention further includes a TOA memory for storing the time-of-arrival of each pulse at an address given by the pulse number. The main memory, organized in the form of a frequency-based histogram, together with the TOA memory, linked to the main memory by means of the pulse number pointer, sorts and records RF signal data with minimal processor control and intervention.
    Type: Grant
    Filed: October 15, 2002
    Date of Patent: February 27, 2007
    Assignee: Alliant Techsystems Inc.
    Inventors: Richard Charles Pringle, Joanna S. Quan
  • Patent number: 7024188
    Abstract: The invention discloses a method for use in a wireless communications system with a plurality of broadcasting nodes, comprising the step of enabling one node in the system to function as a central node in said system and letting said node enable measurements on at least one frequency in a frequency band used by the system. Said measurements are carried out to detect if said at least one frequency is being utilized by a transmitter foreign to the system. Preferably, the measurement is enabled by means of the node transmitting a message to other nodes in the system, said message being a message pre-defined within the system as a message prohibiting all nodes from transmitting during a certain interval, said message being transmitted after the system has been detected by the node to be silent during a predefined interval between frame transmissions from the nodes in the system.
    Type: Grant
    Filed: September 13, 2002
    Date of Patent: April 4, 2006
    Assignee: Telefonaktiebolaget L M Ericsson (publ)
    Inventors: Jamshid Khun-Jush, Peter Schramm, Jan Lindskog, Stefan Rommer, Mathias Pauli, Gerd Zimmermann, Fredrik Johansson, Anders Ranheim, Peter Larsson
  • Patent number: 6995660
    Abstract: A decision aid for use in the defense of a combat ground vehicle which includes a track fusion element, a threat typing element, threat prioritization element, and a countermeasures (CM) selection element.
    Type: Grant
    Filed: January 6, 2003
    Date of Patent: February 7, 2006
    Assignee: Bae Systems Information and Electronic Systems Integration Inc.
    Inventors: Ronald M. Yannone, Howard B. Partin
  • Patent number: 6937639
    Abstract: A system, method and computer program product for positioning pulses, including positioning pulses within a specified time layout according to one or more codes to produce a pulse train having one or more predefined spectral characteristics where a difference in time position between adjacent pulses positioned to produce a spectral characteristic differs from another difference in time position between other adjacent pulses positioned to produce the spectral characteristic. The present invention may include shaping a code spectrum according to a spectral template in order to preserve a pre-defined code characteristic. A pre-defined code characteristic can include desirable correlation, or spectral properties. A transmitter incorporating the present invention can avoid transmitting at a particular frequency. Similarly, a receiver can avoid interference with a signal transmitting at a particular frequency. A radar system, can avoid a radar jammer attempting to jam a particular frequency.
    Type: Grant
    Filed: April 16, 2001
    Date of Patent: August 30, 2005
    Assignee: Time Domain Corporation
    Inventors: Marcus H. Pendergrass, Mark D. Roberts
  • Patent number: 6933878
    Abstract: A wave-form generator drives a number of microwave generating devices each operating at different frequency bands. The output of each microwave generator is connected to its own transmission channel of limited bandwidth which contains all the non-linear components necessary for transmission such as an amplifier, T/R switch, rotary joint and beam switch. These individual channels are finally combined onto a common wideband channel which contains only substantially linear components such as a single waveguide and the antenna itself. Because of the isolation between channels there is little or no opportunity for the generation of harmonics or intermodulation distortions which would otherwise occur in a transmitter capable of operating over a very wide bandwidth.
    Type: Grant
    Filed: November 20, 1985
    Date of Patent: August 23, 2005
    Assignee: Bae Systems Electronics Limited
    Inventor: Robert Bewes Molyneux-Berry
  • Patent number: 6798375
    Abstract: A radar device includes elements for generating a carrier signal having a carrier frequency fT, elements for generating pulses with a pulse repetition frequency fPW, elements for distributing the carrier signal to a transmission branch and a receiving branch, elements for modulate the carrier signal in the transmission path using the undelayed pulses, elements for modulating the carrier signal in the receiving branch using the delayed pulses and for generating a reference signal, elements for mixing the reference signal in the receiving branch with a received signal and elements for integrating the mixed signal. Elements are provided for binary phase shift keying (BPSK) modulation of the carrier signal and elements are provided for switching the polarity of the received signal. A method for suppressing interference in a radar device is also described.
    Type: Grant
    Filed: December 18, 2002
    Date of Patent: September 28, 2004
    Assignee: Robert Bosch GmbH
    Inventor: Thomas Brosche
  • Patent number: 6748351
    Abstract: An apparatus for electronic warfare signal simulation which is used in an external test system to simultaneously test a plurality of “victim” communication systems for vulnerability to jamming. The test system includes a remote radiator of a signal free of jamming effects, and a remote radiator of one or more radio frequency control signals which represent one or more predetermined jamming threats in the low and mid bands.
    Type: Grant
    Filed: November 22, 2000
    Date of Patent: June 8, 2004
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Mark W. Hynes, Robert L. Weeks, James L. Cole, Robert E. Reiner, Timothy T. Taylor
  • Patent number: 6650270
    Abstract: The present invention describes a system for counteracting countermeasures against radar detection. Two known countermeasures are “phase front tilting” and “isotropic scattering.” The invention accomplishes this counteraction by deliberately producing a tilt in the phase front of the transmitted energy. This causes the phase front tilting countermeasure itself to become a tracking signal source for the radar system. The isotropic scatterer types of countermeasures are insensitive to the phase front of the transmitted energy and hence produce return signals which may be distinguished from a true radar echo return signal which is highly sensitive to the phase front of the transmitted energy. Thus this invention provides a radar system having a high degree of immunity to radar countermeasure devices.
    Type: Grant
    Filed: August 15, 1958
    Date of Patent: November 18, 2003
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Bernard L. Lewis
  • Patent number: 6639541
    Abstract: An inexpensive, reliable apparatus and method for autonomously monitoring, measuring the incident level, recording, comparing, reporting, and optionally displaying an indication of intentional or unintentional low-power interfering signals or emissions, including naturally occurring emissions and reflections, as received at the input of an operating system. A particular application of this invention is to monitor, measure, record, compare, report and optionally display an indication of low level interference in the L1 and L2 bands of operation of the NAVSTAR Global Positioning System (GPS). The received signals in L1 and L2 bands are compared to a reference received signal in a third band. This comparison provides a sensitive means to detect the presence of an interfering emission or signal in the L1 band or the L2 band via canceling out the variation in the radiometric scene temperature. The reported data are used for dynamic decision making.
    Type: Grant
    Filed: August 29, 2000
    Date of Patent: October 28, 2003
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Alvin L. Quintana, Mark P. Egan
  • Patent number: 6486824
    Abstract: A tracking radar receiver as described herein is relatively invulnerable to image frequency jamming. Partial image-rejection down-converters down-convert RF signals to IF signals in each of various sum and difference receiver channels. Image frequency components of the IF signals exhibit a predetermined amplitude and phase relationship relative to corresponding real frequency components for each of the channels. Thus, phase and amplitude tracking between the various channels is achieved even when image frequency signals are received.
    Type: Grant
    Filed: July 22, 1985
    Date of Patent: November 26, 2002
    Assignee: General Dynamics Decision Systems, Inc,
    Inventor: Chester D. Shupe
  • Patent number: 6313782
    Abstract: A coded phase modulation communications system which relates to communications systems in which undesired detectability of the radiated signal is materially reduced, and wherein the vulnerability of the system to interfering signals, such as, intentional jamming signals, is substantially reduced. In the system, a radio frequency communications signal is phase modulated by a random or random appearing, but repeatable pattern of noise signal. The received signal is modulated by an identical noise signal, which when synchronized with the original noise modulation results in erasing the noise, and thereby recreating the original, continuous, communications signal. The noise source of the system is a pseudo noise generator that may be readily synchronized with an identical noise source or sources. The pseudo noise generator provides an apparently orderless noise-like sequence that may be exactly reproduced at the same or at a remote location or locations.
    Type: Grant
    Filed: November 16, 1960
    Date of Patent: November 6, 2001
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Frank W. Lehan, Eberhardt Rechtin, Walter K. Victor
  • Patent number: 6141371
    Abstract: A jamming suppression system which includes a plurality of receivers for receiving electromagnetic radiations and a separate notch filter coupled to each receiver for filtering selected frequencies from electromagnetic radiations received by each of the receivers. In accordance with one embodiment of the invention, a spatial combiner responsive to the outputs of each of the notch filters extracts essentially jam-free information from the electromagnetic radiations. In accordance with a second embodiment of the invention, a plurality of spatial combiners, each responsive to the outputs of each of the notch filters, extracts essentially jam-free information from the electromagnetic radiations. The notch filters are adaptive notch filters for on-line selection of their filtering action. One of the notch filters is a master filter and the remainder of the notch filters are slave filters controlled by the master filter.
    Type: Grant
    Filed: December 4, 1997
    Date of Patent: October 31, 2000
    Assignee: Raytheon Company
    Inventors: Jerry D. Holmes, Kenneth S. Barron, Anthony Reid
  • Patent number: 5892477
    Abstract: A radar system (10) uses independent, adaptive modulation controls for the local oscillators (16, 40) in the transmitter (24) and receiver (26) portions. The adaptive modulation enables the radar to filter out any repeater jammer signal while maintaining a good signal-to-noise ratio (SNR) on the target. The radar system (10) provides a SNR that is sensitive to the target range and minimizes the SNR at the jammer range and maximizes the SNR at the target range. A communication system (60) similarly uses independent, adaptive modulation controls (66, 84) to provide a communication system resistant to jamming.
    Type: Grant
    Filed: November 13, 1996
    Date of Patent: April 6, 1999
    Assignee: TRW Inc.
    Inventor: John H. Wehling
  • Patent number: 5539407
    Abstract: A radar apparatus that is provided with auxiliary antennas (5, 10) of an omnidirectional nature. In addition to customary ECCM applications, such as side-lobe suppression and side-lobe blanking, the auxiliary antennas (5, 10) are also used for the emission of frequency-shifted pulses which are emitted simultaneously with radar transmitter pulses. To this effect, the radar apparatus is provided with auxiliary transmitters (8, 13). Furthermore, auxiliary receivers (6, 11) have been provided for analyzing the responses of jammers to the frequency-shifted pulses.
    Type: Grant
    Filed: November 8, 1994
    Date of Patent: July 23, 1996
    Assignee: Hollandse Signaalapparaten B.V.
    Inventor: John A. Scholz
  • Patent number: 5537117
    Abstract: Method and apparatus for enabling a pulse echo radar to generate a false signal in both time and frequency based passive Doppler ESM location systems. The latter false signal causes the ESM system to mislocate the radar. The radar's reference oscillator frequency is varied to create false passive Doppler information at an intercept receiver. These variations are predetermined changes in RF and PRF frequencies for the radar and are relatively small compared to those frequencies.
    Type: Grant
    Filed: August 8, 1995
    Date of Patent: July 16, 1996
    Assignee: Litton Systems, Inc.
    Inventor: Conrad M. Rose
  • Patent number: 5534867
    Abstract: A method and apparatus for controlling the output characteristics of a radar emitter for thereby preventing the location of the emitter using Doppler techniques. The emitter's RF frequency and PRF are under the control of a random signal generator which causes the emitter to emulate common signal corrupting influences.
    Type: Grant
    Filed: June 16, 1995
    Date of Patent: July 9, 1996
    Assignee: Litton Systems, Inc.
    Inventor: Conrad M. Rose
  • Patent number: 5438332
    Abstract: To harden transmissions, in both directions, between a master station (1) and a slave station (2), a table of communication parameter values is memorized in each station and the table values are then used in accordance with the master station's decision. Each message from one station to the other contains information to allow the receiving station to determine the parameter values to be selected in the table to eliminate values where there is a high risk of jamming.
    Type: Grant
    Filed: June 28, 1994
    Date of Patent: August 1, 1995
    Assignee: Thomson-CSF
    Inventors: Daniel Adam, Andre Bech, Alain Desmoucelles, Denis Vallier
  • Patent number: 5377222
    Abstract: A frequency agile spread spectrum radio system which uses a frequency-agile receiver that adaptively learns which frequencies to avoid as being occupied or jammed. The transmitter sends redundant transmissions on widely separated pseudo-random carrier frequencies to overcome jammed channels. A coded preamble is used to provide a greatly enhanced hybrid form of Time Division Multiple Access/Frequency Division Multiple Access for co-existence and frequency re-use with nearby systems. Anti-jam margins of 60 to 90 dB can be inexpensively achieved, far exceeding that of traditional direct sequence systems. The receiver scans the radio spectrum, identifies occupied portions, stores information on these occupied portions, skips over the occupied portions for a set period of time while scanning for radio signals, detects a repetitive preamble code in a received radio signal, maintains the frequency of the received radio signal, and receives and decodes message data in the received radio signal.
    Type: Grant
    Filed: August 10, 1993
    Date of Patent: December 27, 1994
    Assignee: Axonn Corporation
    Inventor: H. Britton Sanderford, Jr.
  • Patent number: 5311541
    Abstract: A frequency agile spread spectrum radio system which is capable of efficient frequency re-use and frequency sharing. The receiver adaptively learns which frequencies to avoid. The transmitter sends redundant transmissions on widely separated pseudo-random carrier frequencies to overcome jammed channels. A coded preamble is used to provide a greatly enhanced hybrid form of Time Division Multiple Access/Frequency Division Multiple Access for co-existence and frequency re-use with nearby systems. Anti-jam margins of 60 to 90 dB can be inexpensively achieved, far exceeding that of traditional direct sequence systems.
    Type: Grant
    Filed: May 8, 1992
    Date of Patent: May 10, 1994
    Assignee: Axonn Corporation
    Inventor: H. Britton Sanderford, Jr.
  • Patent number: 5291202
    Abstract: In a noise radar a pseudo-random sequence is generated repeatedly and used to phase modulate a transmitted signal. The transmission is interrupted during a number of periods during each pseudo-random sequence which allows returns from targets to be received from the same antenna as is used for transmission during those periods of interruption. Each transmitted pulse, between successive periods of interruption, contains a different selection of successive digits of the code thus increasing the apparent randomness of the transmitted code and making detection more difficult.
    Type: Grant
    Filed: May 13, 1986
    Date of Patent: March 1, 1994
    Assignee: GEC Avionics Limited
    Inventor: William J. McClintock
  • Patent number: 5168215
    Abstract: An apparatus and method for measuring the frequencies of a pair of signals simultaneously present in a composite signal, comprising the steps of includes components for squaring the composite signal, filtering the squared signal for separating a first pass band and a higher frequency second pass band, instantaneously measuring the frequencies of the first and second pass bands and determining the individual frequencies of the pair of signals from the measured frequencies of the first and second pass bands.
    Type: Grant
    Filed: November 15, 1991
    Date of Patent: December 1, 1992
    Assignee: Lockheed Sanders, Inc.
    Inventor: Dean C. Puzzo
  • Patent number: 5099194
    Abstract: This proposed approach to extending the frequency range uses non-uniform sampling to gain the advantages of a high sampling rate with only a modest increase in the number of samples. The basic idea is to use two sets of uniform samples with slightly different sampling frequency. Each set of samples is Fourier transformed independently and the frequency of the lowest aliases determined. It is shown that knowledge of these two alias frequencies permits unambiguous determination of the signal frequency over a range far exceeding the Nyquist frequency, except at a discrete set of points. It is further shown that one additional set of samples is sufficient to resolve all these discrete degeneracies.
    Type: Grant
    Filed: March 6, 1991
    Date of Patent: March 24, 1992
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Richard B. Sanderson, James B. Y. Tsui
  • Patent number: 5099243
    Abstract: This is a technique for extending the frequency range which employs in-phase and quadrature components of the signal coupled with non-uniform sampling to gain the advantages of a high sampling rate with only a small increase in the number of samples. By shifting the phase of the local oscillator by 90 degrees, a quadrature IF signal can be generated. Both in-phase and quadrature components are sampled and the samples are combined to form a complex signal. When this signal is transformed, only one alias is obtained per periodic repetition and the effective Nyquist frequency is doubled. Two sets of complex samples are then used with the slightly different sampling frequency. Each set is independently Fourier transformed and the frequency of the lowest aliases permits unambiguous determination of the signal frequency over a range far exceeding the Nyquist frequency.
    Type: Grant
    Filed: March 6, 1991
    Date of Patent: March 24, 1992
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: James B. Y. Tsui, Richard B. Sanderson
  • Patent number: 5017921
    Abstract: A radar system and a method of operating a radar system. The radar system comprises a transmitter-receiver subsystem to transmit a series of electromagnetic pulses, to scan those pulses across an area of interest, and to receive echoes of the pulses. The radar pulses may be transmitted at a multitude of frequencies, each of which is in one of a multitude of channels. The radar system further includes a channel selection subsystem, first, to measure or sample the electromagnetic interference received by the transmitter-receiver subsystem in each of the channels of the radar system during each of at least selected scans of the radar pulses across the area of interest, and second, on the basis of those interferences measurements, to select automatically a channel of the radar system to transmit the radar pulses and to generate a signal identifying that channel.
    Type: Grant
    Filed: December 13, 1989
    Date of Patent: May 21, 1991
    Assignee: Grumman Aerospace Corporation
    Inventors: John McGill, Stanley F. Zoubek, Jr.
  • Patent number: 4996532
    Abstract: A radar system having improved interference resistance. A transmitting section includes an oscillator capable of switching the oscillation frequency, and a transmitting antenna connected to said oscillator and capable of transmitting electric waves having specified transmitting frequencies transmitted in different directions in a specified order to enable a desired range to be scanned. The oscillator and the transmitting antenna are designed to operate so that every time one scanning is completed or every time the transmitting direction is changed during each scanning period, the transmitting frequency may be changed. The receiver can simultaneously form a plurality of beams in the scanning range, convert the received signals to digital signals, and output signals indicating the frequencies and arrival directions of the received signals. The operating mode of the transmitting section may be altered in accordance with the frequency and arrival direction of the received waves.
    Type: Grant
    Filed: December 13, 1989
    Date of Patent: February 26, 1991
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Tetsuo Kirimoto, Takahiko Fujisaka, Yoshimasa Ohashi