Northrop Grumman Systems Corporation

Oak Industries, Inc.

David L Richardson

Scott Alan Stratmoen

Mark D Hischke

Kenneth Duane Gorham

Stuart John Collar

Henry E Lee

Martin J Decker

Graham S Stubbs

Thomas E Szmurlo

Roger Brunner Williams

Raj Mittra

John A Lund

Giora A Bendor

Kenneth Alan Gustafson

Leonard J Kuskowski

Gabor Elek

Barry L Head

Gregory Paul Richardson

Andrzej Sobski

Beverly Jean Timm

An energy conserving tracking tag for receiving a radio frequency location data signal from a global positioning satellite and for communicating with a tracking system. The tag includes a receiver circuit for receiving the location data signal from the global positioning satellite, a customer ID module for generating a unique tag identification signal, a transponder circuit for receiving command signals from the tracking system, and a power circuit electrically engageable with a battery power supply and an external power source. The tag also includes a programmable microprocessor in electrical communication with the power circuit, receiver circuit, customer ID module, and transponder circuit. The microprocessor is operative to collect the location data signal, the identification signal, and the command signals, and subsequently produce an composite output signal. The transponder is further operative to transmit the composite output signal to the tracking system by radio carrier wave.

Energy conserving satellite tracking tag

An RFID system using encoded digital information utilizing pulsed linear frequency modulation (LFM). The LFM waveform is sent from an aircraft or satellite and is received by a transponder. The LFM waveform is demodulated using both, an AM and an FM receiver. The demodulated data is compared to preprogrammed criteria tables, and after validation is decoded and utilized. Algorithms in the transponder are used to determine the frequency deviation and for calculating the direction of the slope of the LFM input signal. The valid RF signal is stored in a delay element, encoded with the transponder data using phase modulation (PM), and frequency modulation (FM). The tag transmission is synchronized to the input LFM waveform. The transmit/receive chopping signal prevents unwanted oscillations and is capable of randomization.

Radio tag for LFM radar

A method of communicating to a RF tag having a low power mode and a scan mode with a radar and an interrogator. The method comprises the steps of alternating the RF tag between the low power mode and the scan mode and then transmitting a wake-up call to the RF tag with the radar. Next, the wake-up call is received from the radar by the RF tag when the RF tag is in the scan mode. Once the wake-up call has been received, the radar will transmit a downlink message to the RF tag. Upon receipt of the downlink message, the RF tag will send an uplinked message to the radar. After the uplink message has been sent to the radar, the RF tag will return to the low power mode. By alternating the RF tag between the low power mode and the scan mode, the power consumption of the RF tag is greatly reduced thereby increasing the battery life thereof.

Tag communication protocol & system

A method, and apparatus for accomplishing the method, for determining the frequency of an RF signal that operates by sequentially applying a received RF signal to sequentially selected individual filters having predetermined frequency pass bands and comparing the magnitudes of the filtered and unfiltered RF signals. The frequency of the RF signal is determined as being within the predetermined frequency pass band of a filter that outputs a largest magnitude output signal relative to the magnitude of the RF signal. Signals of insufficient magnitude are not processed by the system.

Detector system for identifying the frequency of a received signal useful in a channelized receiver

The present invention discloses an apparatus for randomizing the transmit time in a tag RFID communication system. The CRC calculation is implemented through the use of software stored in the system microprocessor and the calculations vary upon a plurality of dynamic inputs including temperature and motion of the tag. The tag apparatus of the present invention includes temperature and motion monitors for monitoring the environmental conditions of the tag. A microprocessor in communication with the sensor calculates the next pseudo-random transmission based upon the dynamic inputs. A transmitter transmits a signal to the system monitor.

Randomization of transmit time

A method and apparatus for decoding a phase encoded data signal utilizes windowed data which is transformed into real and imaginary frequency components thereof. The real and imaginary frequency components are converted into phase and magnitude information. The magnitude information is used to calculate a threshold based upon a signal-to-noise ratio, and the phase of the data signal is corrected by identifying and sorting magnitude peaks. The data signal is differentially demodulated and the demodulated data is then multiplied by a correlation sequence so as to facilitate its being converted into a binary number.

Method and apparatus for decoding a phase encoded data signal

A method for separating a desired signal from an interfering signal, which is particularly useful when the desired signal is substantially weaker than the interfering signal, includes the steps of providing a combined signal which contains both a desired signal and an interfering signal; performing a Fourier transform upon the combined signal; providing a reference function which is a function of the amplitude, frequency and phase of the interfering signal; performing a Fourier transform upon the referenced function; multiplying the real components of the Fourier transform of the combined signal by the real components of the Fourier transform of the reference signal to form a product; and subtracting the product from the Fourier transform of the combined signal to form transformed data less interference, i.e., the desired signal.

Method for separating a desired signal from an interfering signal

A single antenna poly-frequency Continuous Wave (CW) Doppler radar system having leakage cancellation. The system provides for transmitting a plurality of carrier frequency signals and receiving the return signals by means of a single antenna coupled to an antenna interface through which a portion of the transmitted signal may leak. The signal appearing on an output port of the antenna interface is then down-converted to an intermediate frequency (IF) signal by a stable mixing signal. The IF signal is coupled to an adder which in turn is coupled to an output. The IF signal is further split into a pair of cancellation loops for each carrier frequency signal. Each cancellation loop includes a correlator and provides for processing the IF signal with an in-phase or a quadrature-phase signal associated with the carrier frequency signal so that each pair of cancellation loops outputs a feedback signal representative of and equal to the amplitude of the leakage signal only, which feedback signal then being subtracted from the IF signal with the resultant return signal less the leakage signal then being transmitted for further processing. Preferably, a second order linear feedback circuit and phase compensation circuit is provided in each cancellation loop for processing of the IF signal. The disclosed system does not require high precision, high cost oscillators and has particular application in military radars, navigation radars and vehicular collision warning radars.

Poly-frequency CW doppler radar system with leakage cancellation and

A continuous wave diplex Doppler radar, comprising an oscillator generating a transmit signal having a spectrum at a carrier frequency, the oscillator having a frequency control input, and spread spectrum modulation means coupled to the frequency control input for spreading the spectrum of the transmit signal.

Multiple access diplex doppler radar

A collision avoidance system for a vehicle has a vehicle steering sensor for sensing a direction in which the vehicle is being steered, a source of radiation, an articulated reflector for directing radiation from the source in a desired direction, an articulation mechanism for effecting articulation of the articulate reflector, and a close loop control circuit responsive to the vehicle steering sensor for controlling the articulation mechanism so as to cause the articulated reflector to direct radiation in a direction which is generally the same as that direction in which the vehicle is turning.

Vehicle collision avoidance system

A simultaneous signal detector includes components for scaling, by the total signal strength, the difference signal resulting when signals having different frequencies are simultaneously received. As a result, only those inputs which meet both frequency and amplitude difference criteria result in an active SS indication, thereby reducing the number of false active and inactive indications.

Simultaneous signal detector

A device which increases the rate of reduction of spurious output signals includes a path capable of carrying a signal from an input to an output. A plurality of storage elements and a plurality of interspaced switches are serially positioned in the path. Isolation elements are positioned in the path between each storage element and each switch. Multiple reflections from the primary signal are capable of reducing in strength when rebounding between the isolation elements and the switches.

Repeater with low spurious time outputs

A means for coding and decoding video signals by the application of one of a plurality of available scrambling signals includes means for comparing the brightness level during a predetermined time period of the video signal with the brightness level of the video signal over the succeeding predetermined time period. There are means for changing from one scrambling signal to another if the difference between brightness levels in successive predetermined time periods exceeds a given value.

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Arlington Heights, IL, United States of America

David L Richardson