For Pulse Modulation Patents (Class 342/202)
  • Patent number: 5990823
    Abstract: Method and apparatus for developing high range resolution radar target profiles. An outgoing radar waveform is encoded with coefficients corresponding to a wavelet transformation and then transmitted in the direction of a radar target. Incoming waveforms, including return waveforms reflected from the radar target, are decoded using an inverse wavelet transform to produce a high range resolution profile of the target. In an exemplary embodiment, the outgoing waveform is phase-shifted to create finite-duration waveform pulses, each pulse having a phase-state pattern corresponding to a set of coefficients in a transposed wavelet transform matrix. Phase-state duration is adjusted to achieve a desired range resolution.
    Type: Grant
    Filed: May 7, 1997
    Date of Patent: November 23, 1999
    Assignee: Lockheed Martin Corporation
    Inventors: Lawrence C. Peele, Albert N. Pergande
  • Patent number: 5945941
    Abstract: A power distribution system (12) is provided in radar apparatus to distribute power from a 270 VDC source (60) through an intermediate power converter (70) and very high frequency (VHF) regulator/modulator units (80). Bus conductors (71,74) interconnect the source, the intermediate power converter, and the VHF units. Capacitors (71, 76) are connected to the bus conductors on the input and output sides of the intermediate power converter. Each VHF unit supplies modulating pulses to RF amplifiers (82) of an AESA array of the radar apparatus.
    Type: Grant
    Filed: March 12, 1998
    Date of Patent: August 31, 1999
    Assignee: Northrop Grumman Corporation
    Inventors: Edward L. Rich, III, Albert G. Tarrillo
  • Patent number: 5945940
    Abstract: A radar system coherently combines signals from independent upper- and lower-sub-band radars, mutually coheres the sub-band radar signals, and performs model fitting and parameter estimation to obtain ultra-wideband data signatures from a target. Signal processing models are used to compensate for potential lack of mutual coherence between the various sub-bands. An ultra-wideband signal model is fitted to the sparse sub-band measurements to accurately characterize ultra-wideband target scattering and provide for meaningful interpolations or extrapolations outside of the measurement sub-bands.
    Type: Grant
    Filed: March 12, 1998
    Date of Patent: August 31, 1999
    Assignee: Massachusetts Institute of Technology
    Inventor: Kevin M. Cuomo
  • Patent number: 5852418
    Abstract: A notched-chirp generator (20), utilizing first and second chirp generators (28, 30), a functional conversion element (40), an antichirp generator (42), a summing element (64), and a translation element (66), generates a notched-chirp signal (24). The second chirp generator (30) generates a second chirp phase signal (.phi..sub.C1), is translated by the functional conversion element (40) into an oscillating antichirp signal (A.sub.O1). The antichirp generator (42) generates an antichirp signal (A.sub.1) by scaling, weighting, and cyclically positioning the oscillating antichirp signal (A.sub.O1). The summing element (64) sums the antichirp signal (A.sub.1) with a first chirp phase signal (.phi..sub.C0), generated by the first chirp generator (28), to produce a notched-chirp phase signal (.phi..sub.N), which is converted by the translation element (66) into a notched-chirp signal (24) having a notch (26) positioned at a specific frequency (f.sub.N) determined by the antichirp signal (A.sub.
    Type: Grant
    Filed: November 12, 1997
    Date of Patent: December 22, 1998
    Assignee: Lockheed Martin Corporation
    Inventors: Bruce H. Ferrell, William C. Woody
  • Patent number: 5847677
    Abstract: A random number generator for generating a pseudo-random code for use with ittered pulse repetition interval radar systems has been disclosed in which the code generated by the random number generator possesses the five attributes desirable for a jittered radar PRI: a flat frequency spectrum, a nearly perfect spike for an autocorrelation function, a controllable absolute minimum and maximum interval, long sequences that do not repeat, and a reasonable average pulse rate. A method for analyzing the autocorrelation properties of the code generated by the random number generator is also disclosed. A means to generate a pulse signal with random pulse repetition jitter has been disclosed.
    Type: Grant
    Filed: July 7, 1997
    Date of Patent: December 8, 1998
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventor: John W. McCorkle
  • Patent number: 5808580
    Abstract: A method and apparatus for preventing the occurrence of range ambiguities and Doppler ambiguities in both a radar and sonar environment. A series of N pulses are produced, each of which contains a number of contagious subpulses. Each of the subpulses exhibit a different frequency than the remaining subpulses in that particular pulse. Furthermore, the order of appearance of the subpulses in each of the pulses is unique with respect to the remaining pulses in the series. A matched filter receiver and Doppler processor are used to provide auto correlations and cross correlations to prevent the range ambiguities and Doppler ambiguities.
    Type: Grant
    Filed: February 6, 1997
    Date of Patent: September 15, 1998
    Inventor: Grealie A. Andrews, Jr.
  • Patent number: 5777574
    Abstract: An apparatus and method of linear frequency modulation waveform bandwidth multiplication including a digital linear frequency modulation waveform synthesizer for generating a synthesized waveform having an upchirp component of linearly varying frequency during a first half signal duration of the synthesized waveform followed by a downchirp component having linearly varying frequency during a second half of the signal duration of the synthesized waveform. The synthesized waveform is upconverted and subsequently bandpass filtered to provide a filtered waveform to a mixer for mixing with local oscillation signals. The upchirp and downchirp components of the filtered waveform are respectively mixed by first and second local oscillation signals having respective first and second oscillation frequencies in the mixer.
    Type: Grant
    Filed: December 18, 1996
    Date of Patent: July 7, 1998
    Assignee: Northrop Grumman Corporation
    Inventor: John P. Robinson
  • Patent number: 5726657
    Abstract: A radar system in which a frequency agile synthesizer is used to provide rapid frequency shifts and in which measures are taken to maintain phase coherency. The system is fully coherent such that all signals are derived from a common source and are capable of high pulse repetition rates in excess of 1 MHz. There are no inherent transmit duty cycle restrictions and the system is able to transmit complex phase and frequency modulated waveforms. A frequency interleaving scheme is used to resolve range ambiguities at high pulse repetition frequencies and the use of a complementary phase coding scheme allows a high range resolution processing with the transmitted waveforms.
    Type: Grant
    Filed: March 22, 1996
    Date of Patent: March 10, 1998
    Assignee: Lockheed Martin Corporation
    Inventors: Albert N. Pergande, Daniel J. O'Donnell, Albert S. Sabin
  • Patent number: 5703678
    Abstract: A highly precise range measurement instrument is made possible through the use of a novel and efficient precision timing circuit which makes use of the instrument's internal central processing unit crystal oscillator. A multi-point calibration function includes the determination of a "zero" value and a "cal" value through the addition of a known calibrated pulse width thereby providing the origin and scale for determining distance with the constant linear discharge of capacitor.
    Type: Grant
    Filed: September 23, 1996
    Date of Patent: December 30, 1997
    Assignee: Laser Technology, Inc.
    Inventor: Jeremy G. Dunne
  • Patent number: 5673051
    Abstract: Discrete phase modulation for modulating the transmit and receive radar signal waveforms in order to control distortion. The signal is modulated by discrete phases which change from pulse-to-pulse. A digital frequency division circuit accurately generates the modulation signals, and allows the discrete phases to be generated with precise accuracy. The discrete phase changes can be a quadratic phase progression for target Doppler and range detection.
    Type: Grant
    Filed: December 21, 1995
    Date of Patent: September 30, 1997
    Assignee: Hughes Electronics
    Inventors: Howard S. Nussbaum, William P. Posey, Steve I. Hsu, Stephen D. Taylor
  • Patent number: 5574552
    Abstract: A highly precise range measurement instrument is made possible through the use of a novel and efficient precision timing circuit which makes use of the instrument's internal central processing unit crystal oscillator. A multi-point calibration function includes the determination of a "zero" value and a "cal" value through the addition of a known calibrated pulse width thereby providing the origin and scale for determining distance with the constant linear discharge of capacitor.
    Type: Grant
    Filed: January 19, 1995
    Date of Patent: November 12, 1996
    Assignee: Laser Technology, Inc.
    Inventor: Jeremy G. Dunne
  • Patent number: 5563605
    Abstract: A timing generator comprises a crystal oscillator connected to provide an output reference pulse. A resistor-capacitor combination is connected to provide a variable-delay output pulse from an input connected to the crystal oscillator. A phase monitor is connected to provide duty-cycle representations of the reference and variable-delay output pulse phase. An operational amplifier drives a control voltage to the resistor-capacitor combination according to currents integrated from the phase monitor and injected into summing junctions. A digital-to-analog converter injects a control current into the summing junctions according to an input digital control code. A servo equilibrium results that provides a phase delay of the variable-delay output pulse to the output reference pulse that linearly depends on the input digital control code.
    Type: Grant
    Filed: August 2, 1995
    Date of Patent: October 8, 1996
    Assignee: The Regents of the University of California
    Inventor: Thomas E. McEwan
  • Patent number: 5515011
    Abstract: A semiconductor diode is connected across the cathode-to-anode path of a magnetron and through a storage capacitor and collector resistor to a supply voltage for enabling charging of the capacitor. A control pulse causes a switching transistor to conduct to discharge the capacitor through its collector-to-emitter path, an emitter resistor, and the magnetron, for causing the latter to oscillate. A feedback signal representative of the difference between the magnetron output frequency and a reference frequency is applied to a linear amplifier transistor which conducts through the emitter resistor for controlling the current flow through the switching transistor and the operating frequency of the magnetron.
    Type: Grant
    Filed: August 2, 1993
    Date of Patent: May 7, 1996
    Assignee: Litton Systems Inc.
    Inventor: Richard J. Pasco
  • Patent number: 5469479
    Abstract: A monolithic digital chirp synthesizer (DCS) chip using GaAs/AlGaAs HI.sup.2 L technology. The 6500 HBT gate DCS chip is capable of producing linear frequency modulated (chirp) waveforms or single frequency waveforms. The major components of the DCS are two pipelined accumulators, a sine ROM, a cosine ROM and two digital to analog converters.
    Type: Grant
    Filed: February 27, 1992
    Date of Patent: November 21, 1995
    Assignee: Texas Instruments Incorporated
    Inventors: Christopher T.-M. Chang, William A. White
  • Patent number: 5469173
    Abstract: Discernible frequency characteristics regarding BPSK and CW signals are dved from consecutive transform outputs of a dual channel chirp-Z processor. Physically separated antennas direct the signals to the chirp-Z channels and concurrently occurring transforms are directed from those channels to a particular phase detector in accordance with the type of signal to which such transforms relate. The selection of phase detector is made through switches which are controlled by logic circuitry in accordance with the discernible frequency characteristics.
    Type: Grant
    Filed: April 7, 1994
    Date of Patent: November 21, 1995
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventor: William J. Skudera, Jr.
  • Patent number: 5465274
    Abstract: An electronics circuit receives a sub frame of encoded doppler data having roups One through N of data words with the first three words of Group N comprising a frame sync signal which is compared to a reference signal with a sync pulse being generated whenever the signals are identical. This sync pulse is supplied to three counters to load each counter with a predetermined count. The first counter counts the number of words in each Group; the second counter counts the number of Groups in a sub frame and the third counter indicates the location of Automatic Gain Control and Word Width data within the sub frame. Encoded within each group of a Sub Frame are one or more clusters of doppler words with a fourth counter indicating the location of these clusters of doppler words. A word decoder circuit in response to a gain signal and a word width data signal decodes each word of each group of the sub frame having doppler data to extract the doppler data.
    Type: Grant
    Filed: April 7, 1995
    Date of Patent: November 7, 1995
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Christian L. Houlberg
  • Patent number: 5389932
    Abstract: A pulse compression control system uses a code sequence having a larger self correlation side lobe level compared with an ideal code sequence as a transmission code sequence and includes a modulating unit for modulating a pulse by the transmission code sequence in a first order modulation unit. The pulse is received in a demodulating unit where it is demodulated. A reception code sequence from the demodulation unit is modulated by a key code sequence in a second order modulation unit so as to convert it to the ideal code sequence. A self correlation processing unit processes the ideal code sequence for pulse compression.
    Type: Grant
    Filed: February 10, 1993
    Date of Patent: February 14, 1995
    Assignee: Fujitsu Limited
    Inventors: Eikichi Ota, Asao Komata
  • Patent number: 5351053
    Abstract: A radar system that includes an ultra wideband radar signal processor for electronically scanned arrays that utilizes frequency offset generation (FOG) to achieve beam steering as compared with phase shift and time delay techniques of conventional radars. The device comprises a transmit antenna, a chirp generator connected to the transmit antenna and a first summing circuit, a receiver antenna connected to the first summing circuit, a Doppler de-ramping chirp circuit connected to a second summing circuit, the output of the second summing circuit connected to an amplitude and weighting circuit and the output of the amplitude circuit connected to a spectrum analyzer of a Fast Fourier Transform (FFT) circuit. The signal processing consists of mixing the target returns with the transmitted signal to obtain a video beat note signal. This video beat note signal is mixed with a Doppler de-ramping chirp waveform which is matched to the desired target velocity.
    Type: Grant
    Filed: July 30, 1993
    Date of Patent: September 27, 1994
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Michael C. Wicks, Russell D. Brown
  • Patent number: 5347281
    Abstract: A pulse-compression, MTI, doppler-radar system for determining target velty information from a single, frequency-coded uncompressed target-return pulse includes a coded modulator, two pulse compressors, and a phase-comparison processor. The coded modulator generates for transmission an uncompressed pulse with the first and second halves of the pulse coded with the even and odd harmonic sidebands of a pulse repetition frequency, respectively. The first and second halves of the pulse returning from the target are pulse compressed simultaneously by the two pulse compressors. The phase comparison processor then determines the phase difference between the compressed pulses to obtain the target velocity information.
    Type: Grant
    Filed: July 23, 1976
    Date of Patent: September 13, 1994
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventors: Bernard L. Lewis, Ben H. Cantrell
  • Patent number: 5325099
    Abstract: A modular solid-state radar transmitter apparatus for producing waveforms whose amplitude may be varied over time. The transmitter achieves pulse modulation on either an intrapulse or pulse to pulse basis, while at the same time reducing stress on individual solid-state modules. Intrapulse modulation and pulse to pulse modulation can be produced with the disclosed modular solid-state transmitter because the number of modules and the sequence in which they are activated is selectable. These selections provide the various desired levels of transmitted power and thus effectively achieve modulation. In order to achieve this intrapulse modulation, a variable combiner is introduced whose coupling factor is coordinated with the module activations. In one embodiment, variable combining is accomplished by the use of RF switching logic for combining pairs of signals in parallel. In this case, RF switches are programmed to act as a conventional combiner when all modules are active.
    Type: Grant
    Filed: April 28, 1993
    Date of Patent: June 28, 1994
    Assignee: ITT Corporation
    Inventors: Jeffrey T. Nemit, Arthur Y. Okamura, John M. Milan
  • Patent number: 5321409
    Abstract: A radar system (20) has a chaotic code source (22) with a chaotic code output (23), which generates a chaotic code according to a chaotic difference equation. The radar system (20) further includes a transmitter (24) with a carrier signal source (28) of a carrier signal (29), and an encoder (30) having as a first input the carrier signal (29) of the carrier signal source (28) and as a second input the chaotic code output (23) of the chaotic code source (22), and as an output a transmitted radar signal (36) having the chaotic code output (23) encoded onto the carrier signal (29). A radar system receiver (26) includes a correlator (46) having as a first input the chaotic code output (23) of the chaotic code source (22) and as a second input a received radar signal (44), and as an output an indication of the correlation of the first and second inputs. The correlation is used to determine the distance, speed, or other characteristic of an object that reflected the radar signal.
    Type: Grant
    Filed: June 28, 1993
    Date of Patent: June 14, 1994
    Assignee: Hughes Missile Systems Company
    Inventor: W. T. Walker
  • Patent number: 5311193
    Abstract: A digital chirp generator for generating linear frequency modulated signals, comprises a plurality of frequency/phase accumulators pipelined together. Each frequency/phase accumulator includes a frequency accumulator driving phase accumulator. In the pipelined configuration the frequency accumulator and the phase accumulator of each frequency/phase accumulator are interconnected with the corresponding frequency accumulator and phase accumulator adjacent of the frequency/phase accumulator.
    Type: Grant
    Filed: September 16, 1991
    Date of Patent: May 10, 1994
    Assignee: British Aerospace Public Limited Company
    Inventor: Stephen M. Parkes
  • Patent number: 5278567
    Abstract: Received expanded radar pulses pass through a surface acoustic wave (SAW) weighted filter (64) for sidelobe suppression, and then into a SAW tapped delay line (66). The pulses appear at the taps (66a,66b,66c) of the delay line (66) coarsely aligned in time, pass through individual SAW matched filters (68,84,86,88) for compression and envelope detectors (70,90,92,94) for demodulation, and then into a summer (74) for post detection integration. Individual frequency shifters (78,80,82) are provided between the delay line taps (66a,66b,66c) and the matched filters (84,86,88) for shifting the center frequencies of the pulses and thereby the propagation delays through the matched filters (84,86,88) to provide fine alignment of the pulses in time. The delays through the individual delay line taps (66a,66b,66c) and the frequency shifts of the frequency shifters (78,80,82) are adjustable "on the fly" to compensate for variation of pulse repetition rate (PRF) and interpulse jitter.
    Type: Grant
    Filed: November 25, 1991
    Date of Patent: January 11, 1994
    Assignee: Hughes Aircraft Company
    Inventor: Charles E. Nourrcier
  • Patent number: 5248975
    Abstract: A ground probing radar system comprising a plurality of antennas for transmitting. Where for each transmitting antenna, an associated individual driver means selectively operable in response to an enabling signal unique to each antenna. Upon receiving a triggering signal, the driver means supplies to its associated antenna a single impulse of power to be radiated. Further providing that a means for supplying the trigger signal to each of the driver means only one at a time, thereby insuring that no two antennas are supplied power to be radiated at the same time.
    Type: Grant
    Filed: June 26, 1991
    Date of Patent: September 28, 1993
    Assignee: Geophysical Survey Systems, Inc.
    Inventor: Alan E. Schutz
  • Patent number: 5247308
    Abstract: BPSK signals are detected by receiving an input signal containing the BPSK ignals to be detected, by means of a compressive receiver; applying the receiver output to a 90.degree. phase shifter which outputs a phase-shifted signal; applying the phase-shifted signal to a delay line which applies a further phase shift of -180.degree. to the phase shifted signal; and detecting the relative phase of the non-phase-shifted signal from the compressive receiver and the phase-shifted signal from the delay line by applying those signals to respective input ports of a phase detector, the output of the phase detector being indicative of detection of a BPSK signal. Advantageously, zero-crossings of the output signal of the phase detector are detected, and the output of the zero-crossing detector is low-pass-filtered.
    Type: Grant
    Filed: February 24, 1993
    Date of Patent: September 21, 1993
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventor: Charles E. Konig
  • Patent number: 5192956
    Abstract: The present invention is a system that performs code compression in stages where each stage includes two processing paths 36 and 38. The two paths allow bidirectional crossover cascade complementary code compression reducing the number processing stages to log.sub.2 N and reducing the number of processing by a factor of N/(2 log.sub.2 N) where N is the length of the code. Each path includes a delay provided by a delay unit 44 and each path arithmetically combines the data from its own path with data from the other path. The upper path 36 uses an adder 40 while the lower path uses an adder/substracter unit 42 which adds or subtracts depending on the phase of the transmitted complementary phase code. The delay provided in each stage increases in a binary progression with the delay of the last stage being N/2. A systolic processor 68 is the preferred embodiment although the invention could be implemented in a programmable digital signal processor.
    Type: Grant
    Filed: November 13, 1991
    Date of Patent: March 9, 1993
    Assignee: Westinghouse Electric Corp.
    Inventor: Henry E. Lee
  • Patent number: 5177486
    Abstract: A high voltage sub-nanosecond pulser and radiator including a radial transsion line consisting of a dielectric member sandwiched between two patterned layers of metallization, one of which comprises a plurality of radiating elements. A photoconductive semiconductor gallium arsenide switch is embedded in the dielectric member which has a constant thickness. The other layer of metallization includes an apertured grid adjacent one surface of the switch for application of an energization pulse of laser light.
    Type: Grant
    Filed: November 25, 1991
    Date of Patent: January 5, 1993
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Anderson H. Kim, Maurice Weiner, Louis J. Jasper, Jr., Thomas E. Koscica, Robert J. Youmans
  • Patent number: 5146616
    Abstract: A predetermined radar pulse train is formed in space by transmitting individual spectral components thereof. Thus, a train of extremely short pulses is obtained without switching a radio frequency signal on and off at a high rate. A crystal oscillator is coupled to a harmonic generator such as a comb generator. A power divider distributes the output of the harmonic generator to a multiplicity of final filter amplifiers. Each final filter amplifier has a phase-locked VCO circuit that provides frequency accuracy, spectral purity, low noise and frequency stability. Thus, each final filter amplifier provides one of the spectral components of the predetermined radar pulse train. The final filter amplifiers are coupled by duplexers to a broadband multiplexing feed such as a nested cup dipole feed that illuminates a reflector. On receive, the broadband multiplexing feed separates all the spectral components of the incoming pulse train.
    Type: Grant
    Filed: June 27, 1991
    Date of Patent: September 8, 1992
    Assignee: Hughes Aircraft Company
    Inventors: Raymond Tang, James G. Small
  • Patent number: 5140332
    Abstract: A radar system is disclosed which includes a transmitter which produces a long coded radar pulse. The return of the long coded radar pulse is compressed by a long pulse compression filter to produce a short coded pulse and the short coded pulse is compressed by a short pulse compression filter to produce a return pulse for processing by an existing processor designed to process return coded pulses of a particular format. The long pulse transmitter can also transmit a short coded precursor pulse, to improve radar range coverage, along with the long coded pulse by the provision of a switching bypass device which routes the short coded pulse return signal around the long pulse compression filter.
    Type: Grant
    Filed: October 25, 1991
    Date of Patent: August 18, 1992
    Assignee: Westinghouse Electric Corp.
    Inventors: Raymond G. Martin, Gregory S. Hill
  • Patent number: 5084706
    Abstract: A transmitter array includes a number of individual transmitters, each contributing a series of short microwave pulses each consisting of only several cycles to make up an RF pulse in the far field. Apparatus for closed loop synchronizing the pulses from each transmitter in order to maximize the amplitude of the RF pulse includes a Voltage Control Oscillator which provides a continuous wave (CW) reference to each transmitter and includes apparatus for dividing the CW down to feed a series of timers in each transmitter, each timer having a means for setting the time and duration of firing and providing an output signal synchronously related to the CW. A dual polarity peak detector fine tunes the individual transmitters via closed loop feedback to compensate for any thermal drift. A novel time delay vs. voltage transducer is used to achieve closed loop synchronization. Short term pulse jitter is significantly reduced by overtriggering the avalanche transistor.
    Type: Grant
    Filed: December 15, 1989
    Date of Patent: January 28, 1992
    Inventors: Gerald F. Ross, Richard M. Mara
  • Patent number: 5059966
    Abstract: A synthetic aperture radar system wherein a plurality of beams is formed for receiving echo signals and the spectra of the received signals are synthesized in an azimuth compression unit to improve the cross-range resolution.
    Type: Grant
    Filed: February 8, 1990
    Date of Patent: October 22, 1991
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Takahiko Fujisaka, Yoshimasa Oh-Hashi
  • Patent number: 5032843
    Abstract: A radar device, of the almost linearly frequency-modulated type of the transmission signal during the pulse, comprises a transmit circuit including a high-frequency oscillator (29), a transmit-receive aerial (7) and a receive circuit including a pulse compression element (33). According to the invention, inside the transmit circuit, an Impatt diode (17) of a diode switch (16) produces directly at microwave frequency a synchronizing signal of the oscillator (pulses modulated in accordance with negative frequency slopes). For this purpose, a clock pulse generator (26) commands a switch (25) arranged in series on the conductor (19) of the supply current of the Impatt diode (17) which current is substantially continuous, to conduct for the duration of each pulse to be transmitted.
    Type: Grant
    Filed: December 13, 1988
    Date of Patent: July 16, 1991
    Assignee: U.S. Philips Corporation
    Inventor: Jean-Marie Zilliox
  • Patent number: 5019826
    Abstract: A portion of a radar transmit pulse is inserted into a recirculating delay line having a one cycle delay equal to the duration of a transmit pulse. A pulse train coupled from the recirculating delay serves as a local oscillator for the radar receiver. The delay medium may be an optical fiber, a coaxial transmission line or a surface acoustic wave (SAW) device.
    Type: Grant
    Filed: September 29, 1988
    Date of Patent: May 28, 1991
    Assignee: Hughes Aircraft Company
    Inventors: Michael de La Chapelle, Richard E. Bryan, Clark D. Brenneise
  • Patent number: 5005018
    Abstract: A modulator provides a continuous signal format composed of discrete freqcy steps and is designed to eliminate frequency overlap or smearing normally associated with filter ringing.
    Type: Grant
    Filed: October 6, 1982
    Date of Patent: April 2, 1991
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Glenn A. Walters
  • Patent number: 4975706
    Abstract: A radar system adapted to operate with a selected one of a plurality of pulse repetition intervals to produce a corresponding train of transmitted pulses of radio frequency energy in response to a train of trigger pulses and to receive returns from objects in response thereto, with returns from stationary objects producing signals with the same phase shift relative to the phase of a reference signal. The system includes a switching circuit responsive to a signal representative of the selected one of the pulse repetition intervals, for producing charge controlling signals with time intervals between the charge controlling signals and the trigger pulses being selected in accordance with the selected one of the pulse repetition intervals. A pulse forming network, is provided for storing energy in response to the charge controlling signals and for providing output pulses in response to the trigger pulses.
    Type: Grant
    Filed: November 6, 1989
    Date of Patent: December 4, 1990
    Assignee: Raytheon Company
    Inventor: William W. Shrader
  • Patent number: 4952940
    Abstract: In a radar system, comprising a digital expander, two analog modulation signals are generated with two digital to analog converters and raised to an intermediate frequency range through a quadrature modulator. The amplitude and phase ripple of the output signal occurring in the quadrature modulator due to limited carrier and image frequency suppression are compensated through a multiple regulating circuit. To this end, if necessary calibration signals, of constant amplitude and different phase positions, are generated sequentially by means of the two digital to analog converters and the amplitude of their output signals measured in an amplitude detector. Setting values for the multiple regulating circuit are determined from the averaged amplitude measured values in a phase and amplitude correction unit which via setting elements set the requisite offset and phase and amplitude symmetry values until the deviations of the output signal in amplitude and phase disappear.
    Type: Grant
    Filed: January 18, 1989
    Date of Patent: August 28, 1990
    Assignee: Siemens-Albis
    Inventor: Hanspeter Kuepfer
  • Patent number: 4952941
    Abstract: A method in circuit for controlling the temperature of IMPATT diodes during pulsed operations: first, by providing a switch of the RF energy produced by the IMPATT for switching the IMPATT output from an antenna to an internal load, the switch being a pin diode switch; secondly, switching the output of a pair of IMPATT diodes from an antenna to an internal load by providing a selective phase shifter for shifting the phase of the injection signal to one of the IMPATT diodes and further providing a hybrid coupler at the output ends of the IMPATT diodes and disposed between the antenna and the internal load; thirdly, providing a pair of injection signal sources which operate on different frequencies and alternately switching the separate injection sources with the input end of an RF producing IMPATT diode; and fourthly, providing a positive biased pre-heat current pulse to the RF producing IMPATT.
    Type: Grant
    Filed: September 13, 1989
    Date of Patent: August 28, 1990
    Assignee: Rockwell International Corporation
    Inventor: Don L. Landt
  • Patent number: 4935744
    Abstract: The invention relates to a coherent radar comprising a magnetron (MAG), a modulator (MOD) for pulsing the magnetron, a stable local oscillator (STALO) and a mixer (B.sub.1) for producing an intermediate frequency signal of incoming echoes and an intermediate frequency oscillator (MFO) and a phase sensitive detector (D) for detecting the echo pulses and producing a so called bipolar video signal. The modulator (MOD) and the intermediate frequency oscillator (MFO) are mutually time controlled in such manner that the front flank of the modulator pulse and thereby the magnetron pulse always appears in a predetermined phase position of the output signal of the intermediate frequency oscillator. According to the invention the oscillations of the magnetron are phase locked to an external signal in two steps. This is effected by applying a signal derived from the stable local oscillator to the tuning cavities of the magnetron before triggering.
    Type: Grant
    Filed: April 10, 1989
    Date of Patent: June 19, 1990
    Assignee: U.S. Philips Corporation
    Inventors: Kjell S. Anflo, J. Werner Ingvar Grabs
  • Patent number: 4926185
    Abstract: A pulse radar system including an RF exciter for generating a repeating sequence of internal pulses of RF energy of different frequencies. A transmit circuit responsive to the internal pulses of RF energy generates a transmit radar signal comprising a transmit repeating sequence of transmit intervals during which pulses of RF energy are transmitted. A single receiver responsive to the repeating sequence of internal RF pulses receives radar return signals based on all of the RF frequencies in a receive repeating sequence of receive intervals which do not occur at the same time as said transmit intervals.
    Type: Grant
    Filed: October 26, 1988
    Date of Patent: May 15, 1990
    Assignee: Hughes Aircraft Company
    Inventor: Peter Wittenberg
  • Patent number: 4890109
    Abstract: A broadband RF microwave source is used to generate a high-energy, narrow lse which is used to provide the illuminating signal for an active radar system while simultaneously jamming other active radar systems. The generation of the RF microwave energy utilizes a spark gap generation system. Jamming is accomplished by overload ringing of the receiver portion of the other radar systems.
    Type: Grant
    Filed: July 13, 1977
    Date of Patent: December 26, 1989
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Richard P. Gagliardi
  • Patent number: 4884077
    Abstract: A method in circuit for controlling the temperature of IMPATT diodes during pulsed operations: first, by providing a switch of the RF energy produced by the IMPATT for switching the IMPATT output from an antenna to an internal load, the switch being a pin diode switch; secondly, switching the output of a pair of IMPATT diodes from an antenna to an internal load by providing a selective phase shifter for shifting the phase of the injection signal to one of the IMPATT diodes and further providing a hybrid coupler at the output ends of the IMPATT diodes and disposed between the antenna and the internal load; thirdly, providing a pair of injection signal sources which operate on different frequencies and alternately switching the separate injection sources with the input end of an RF producing IMPATT diode; and fourthly, providing a positive biased pre-heat current pulse to the RF producing IMPATT.
    Type: Grant
    Filed: January 27, 1988
    Date of Patent: November 28, 1989
    Assignee: Rockwell International Corporation
    Inventor: Don L. Landt
  • Patent number: 4851852
    Abstract: A pulsed coherent radar altimeter is described which employs a narrow band receiver and utilizes a novel digital coherent pulse generator. A coherent pulse radar transmits a pulse comprised of the sum of at least two phase related RF signals closely spaced in frequency. The phase shift due to platform motion and return surface irregularity of the return signal is approximately the same for each carrier. The receiver produces a signal representative of the difference of the two carriers which is substantially free of decorrelation effects, and which can be processed in a narrow band receiver to produce range information.
    Type: Grant
    Filed: April 20, 1987
    Date of Patent: July 25, 1989
    Assignee: Honeywell Inc.
    Inventors: Merlin D. Bjorke, Baard H. Thue
  • Patent number: 4827267
    Abstract: A solid state radar transmitter pulse modulator system capable of generating high power operating pulses having pulse width and pulse repetition rate agility and being programmable for output pulse current over a substantial range of peak current values to produce corresponding values of transmitter output power. A multi-stage cascade cross-field amplifier (CFA RF chain) is employed, each stage having its own pulse modulator comprised of one or more standard modules paralleled at the output to drive the corresponding CFA stage provides fail-soft operation. Means are included for protecting solid state circuits in the event of CFA or other component failures, for dynamically matching CFA and pulse transformer impedances, and for preventing BH curve "walk-up" during operation.
    Type: Grant
    Filed: November 19, 1987
    Date of Patent: May 2, 1989
    Assignee: ITT Gilfillan
    Inventor: Thayer L. Shearin
  • Patent number: 4774517
    Abstract: Voltage regulator which can compensate for the output voltage variation of a line modulator for use in transmitters for radar applications. The voltage variation in question is due to the modulation induced by the radar repetition frequency. This regulator is essentially made up of a network (1,2,3,4,5,6,7) which varies the value of the input signal to a comparator 8 in relation to a signal which is proportional to the variation of repetition frequency.
    Type: Grant
    Filed: May 18, 1987
    Date of Patent: September 27, 1988
    Assignee: Selenia, Industrie Elettroniche Associate, S.p.A.
    Inventors: Piero Cervone, Ennio Giaccari, Roberto Pace
  • Patent number: 4682178
    Abstract: The invention relates to a coherent radar comprising a magnetron (10), a modulator (12) for pulsed driving if the magnetron, a stable local oscillator (22) and mixer (20) for producing an intermedicate frequency signal of incoming echoes and an intermediate frequency oscillator (28) and phase sensitive detector (26) for detecting the echo pulses in order to generate a so called bipolar video signal. According to the invention a HF-signal derived from the stable oscillator (22) is fed to the tuning cavities of the magnetron (10), so called priming, at least in the transmission moment, and furthermore the modulator (12) and the intermediate frequency oscillator (28) are mutually time controlled in such manner that the leading edge of the modulator pulse and thereby of the magnetron pulse always appears in a given phase position of the output signal from the intermediate frequency oscillator, for example a zero passage.
    Type: Grant
    Filed: January 11, 1985
    Date of Patent: July 21, 1987
    Assignee: U.S. Philips Corporation
    Inventors: Kjell S. Anflo, Jan W. I. Grabs
  • Patent number: 4680722
    Abstract: An arrangement for determining the starting instant t.sub.o of the leading edge of a received high-frequency pulse signal V of the formV=A.(t-t.sub.o).sin 2.pi.Ft,whereV is the instantaneous voltage,A is the slope (which is unknown) of the leading edge,t is the time, andF is the frequency.The arrangement includes delay means for delaying the received pulse by a period of time equal to k/2F (where k is an integer) and for thus producing a second pulse signal V.sub.R of the formV.sub.R =A.(t-t.sub.o -(k/2F)).sin 2.pi.[F(t-(k/2F))]The pulse signals are applied to calculating means which determines t.sub.
    Type: Grant
    Filed: February 11, 1985
    Date of Patent: July 14, 1987
    Assignee: U.S. Philips Corporation
    Inventor: Jean-Pierre Tomasi
  • Patent number: 4667200
    Abstract: A pulse radar apparatus is provided with a coherent transmitting and receiving unit (1) for the transmission of radar pulses, the reception of echo signals, and the conversion of the echo signals into signals of an intermediate frequency f.sub.if, which may be shifted through a Doppler frequency f.sub.d. The echo signals with frequency f.sub.if +f.sub.d are fed to a detector (7) for the coherent phase detection with a frequency f.sub.if +f.sub.c. The detected signals are fed to an analog-to-digital converter (10), which operates at a frequency of approximately 4f.sub.c. The pulse radar apparatus further includes accumulators (12, 13), alternately fed with the output signals of the analog-to-digital converter (10) each time for a given period, after which period the output signals of the accumulators (12, 13) are representative of the orthogonally detected components of the echo signals.
    Type: Grant
    Filed: November 9, 1983
    Date of Patent: May 19, 1987
    Assignee: Hollandse Signaalapparten B.V.
    Inventors: Bernard Gellekink, Willem A. Hol