Signal processing architecture which improves sonar and pulse Doppler radar performance and tracking capability

A method for performing enhanced signal detection for use with a fast Fourier transform (FFT) processor having a plurality of filters, comprising the steps of:

• measuring predetermined FFT output parameters;
• sequentially adjusting FFT output based on said predetermined output parameters;
• sequentially correcting FFT output phase for all potential signal filter offset positions;
• and
• selecting signal filter offset where minimum phase standard deviation occurs.

A method for detecting signals for use with a fast Fourier transform processor having a plurality of filters, comprising the steps of:

• determining individual filter number phase rotation, filter signal position, and mean signal phase shift for signals in the FFT filters;
• correcting original values of phase for filter number phase rotation, filter signal position measured, and mean signal phase shift;
• and
• performing a predetermined detection algorithm to declare detections.

A system comprising:

• a Fourier transform processor;
• means for performing high resolution frequency measurement, phase measurement and standard deviation measurements on FFT output signals of said processor;
• and
• a frequency rate of change template used in conjunction with a lowest standard deviation evaluator of said FFT output signals to determine frequency rate of change of the signal to be detected.

A system comprising:

• a Fourier transform processor;
• and
• a first system for performing high resolution frequency measurement, phase measurement and standard deviation measurements of filter output data of said processor, wherein said first system comprises:
• a filter;
• a filter number phase corrector;
• a filter unit phase rotation corrector;
• a mean phase calculator;
• a standard deviation calculator;
• a lowest standard deviation evaluator;
• wherein said filter unit phase rotation corrector, said mean phase calculator and said lowest standard deviation evaluator iteratively step through all filter positions in said filter;
• and
• a frequency calculator.

A system comprising:

• a Fourier transform processor:
• a first system for performing high resolution frequency measurement, phase measurement and standard deviation measurements of filter output data of said processor;
• and
• a second system to provide a processing data channel to enhance signal processing to support signal detection, wherein said second system comprises a phase corrector and a pseudo coherent integrator, and further wherein said phase corrector corrects the signal for filter number phase rotation, filter signal position determined by said lowest standard deviation evaluator and mean signal phase shift calculated and stores the rotated results.

A system comprising:

• a Fourier transform processor;
• a first system for performing high resolution frequency measurement, phase measurement and standard deviation measurements of filter output data of said processor;
• and
• a second system to provide a processing data channel to enhance signal processing to support signal detection, wherein said processing data channel defines a first processing data channel, and further comprising a third system to provide a second processing data channel to enhance signal processing to support co-operative signal detection with said first processing data channel, and further wherein said third system comprises a linear/square law detection of the FFT outputs and integrating consecutive outputs to provide said second data channel for use in combination with a pseudo coherently integrated data channel for improved signal detection.

A system comprising:

• a Fourier transform processor;
• a first system for performing high resolution frequency measurement, phase measurement and standard deviation measurements of filter output data of said processor;
• and
• a second system to provide a processing data channel to enhance signal processing to support signal detection, wherein said processing data channel defines a first processing data channel, and further comprising a third system to provide a second processing data channel to enhance signal processing to support co-operative signal detection with said first processing data channel, and further wherein said data channel signals are detected as single filter signal detection which includes a ratio check of a filter that is pseudo coherent integrated versus a same filter linear/square law detected and integrated, and if the ratio exceeds a predetermined threshold and if the standard deviation values are smaller than a predetermined value, a detection is declared.

A system comprising:

• a Fourier transform processor;
• a first system for performing high resolution frequency measurement, phase measurement and standard deviation measurements of filter output data of said processor;
• and
• a second system to provide a processing data channel to enhance signal processing to support signal detection, wherein said processing data channel defines a first processing data channel, and further comprising a third system to provide a second processing data channel to enhance signal processing to support co-operative signal detection with said first processing data channel, and further wherein said data channel signals are detected as (a) a two channel summed signal detection which includes a summer to sum like filters that are linear/square law detected and integrated and pseudo coherently integrated, (b) a filter that filters detection candidates using predetermined standard deviation values, and (c) a multi-pass local mean signal determination unit that removes strong signals from mean calculations and detects based signals exceeding threshold mean values.

A system comprising:

• a Fourier transform processor;
• a first system for performing high resolution frequency measurement, phase measurement and standard deviation measurements of filter output data of said processor;
• and
• a second system to provide a processing data channel to enhance signal processing to support signal detection, wherein said processing data channel defines a first processing data channel, and further comprising a third system to provide a second processing data channel to enhance signal processing to support co-operative signal detection with said first processing data channel, and further wherein said data channel signals are detected as (a) a two pass mean two pass threshold signal detection which comprises a two pass local mean calculator which removes strong signals from mean calculations, (b) a threshold detector that detects based on signals exceeding threshold mean of said second pass, and (c) a second threshold detector which filters detection candidates using predetermined standard deviation values.

A system comprising:

• a Fourier transform processor;
• a first system for performing high resolution frequency measurement, phase measurement and standard deviation measurements of filter output data of said processor;
• and
• a second system to provide a processing data channel to enhance signal processing to support signal detection, wherein said processing data channel defines a first processing data channel, and further comprising a third system to provide a second processing data channel to enhance signal processing to support co-operative signal detection with said first processing data channel, and further wherein said data channel signals are detected as (a) an adjacent bin signal detection which includes a mean calculator, (b) a strong signal removal from mean calculations and recalculation, (c) an adjacent bin correlator, (d) a weighted summer to add signals from adjacent filters, and (e) a detector which detects based on summed signals exceeding threshold mean values and thresholded standard deviation values.

A system comprising:

• a systematic processor of FFT processed data;
• and
• a measuring system to perform high resolution frequency measurement,
• wherein said measuring system comprises:
• a memory unit for pertinent data storage over integration time;
• a FFT processor unit converting time domain signals to frequency domain;
• a linear detector converting real and imaginary filter outputs to magnitude;
• and
• a frequency measurement unit to determine position of signal in a filter.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• architecture means for resolving range ambiguity through systematic changes of transmitter pulse recurring frequency (PRF) of said Doppler radar programmable event generator on a scan to scan basis.

A pulsed Doppler radar system comprising an antenna unit;

• a transmitter for transmitting a signal through said antenna unit, a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• architecture means for establishing an architecture that improves system performance through systematic control of transmitter pulse recurring frequency (PRF) of said Doppler radar programmable event generator on a scan to scan basis, wherein the architecture means comprises a scheduler for changing the PRF on a scan to scan basis wherein each PRF value used has been predetermined and each PRF to PRF mathematical relationship is chosen to maintain spacing greater than three range gates for the number of folds required to meet maximum range requirements without fold redundancy.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• resolving means for resolving range ambiguity by changing transmitter pulse recurring frequency (PRF) on a scan to scan basis of said detected signals.

A pulsed Doppler radar system comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• resolving means for resolving range ambiguity on a scan to scan basis of said detected signal, wherein said resolving means comprises:
• (a) a detection sorting unit to pair detections from different scans, (b) a radar motion calculator, (c) an equation iteration unit to systematically sequence numeric values searching for equation equality, (d) a range check that confirms unambiguous range of the correlated calculations, and (e) a range calculator that calculates unambiguous range.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• compression means for providing frequency domain pulse compression of said FFT processed received signals.

A pulsed Doppler radar system comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal, wherein the improvement comprises:
• compression means for providing frequency domain pulse compression of said FFT processed received signals, wherein said compression means comprises:
• (a) a phase shifter that phase shifts real and imaginary filter outputs of consecutive range bins from a filter involved in the pulse compression by the amounts required to compensate each range bin for the pulse compression coding, and (b) a summer to add the shifted range bins.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• performing means for performing frequency domain pulse compression and Doppler ambiguity resolution on said FFT processed received signals at constant PRF.

A pulsed Doppler radar system comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• performing means for performing frequency domain pulse compression and Doppler ambiguity resolution on said FFT processed received signals at constant PRF, wherein said performing means comprises:
• (a) a phase shifter that phase shifts real and imaginary filter outputs of consecutive range bins from a filter involved in the pulse compression amounts based on Doppler frequency involved and pulse compression coding, (b) a Doppler term numeric calculator to determine an amount of phase shift to be used for pulse compression over multiple Doppler folds for both inbound and outbound Doppler, (c) a summer to sum the phase rotated results;
• (d) a detector/integrator to integrate the magnitudes of each filter, (e) a memory storage unit to store results, (f) a CFAR detector operating at a high false alarm rate to determine range bin and Doppler filters that Doppler ambiguity is to be resolved, and (g) a Doppler ambiguity resolution unit that resolves Doppler ambiguity.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• performing means for performing high resolution frequency measurement, phase measurement and standard deviation measurements on said FFT processed received signals;
• and
• determining means for determining a heading of an unambiguous range detected target by said heading calculator and accurate frequency measurement.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• performing means for performing high resolution frequency measurement, phase measurement and standard deviation measurements on said FFT processed received signals;
• and
• improving means for improving azimuth resolution of said Doppler radar.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• performing means for performing high resolution frequency measurement, phase measurement and standard deviation measurements on said FFT processed received signals;
• and
• improving means for improving range accuracy and minimizing performance losses due to range gate straddle of said target signals with regard to analogue to digital range gate conversions.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• performing means for performing high resolution frequency measurements, phase measurement and standard deviation measurements on said FFT processed received signals;
• and
• removing means for removing same target multiple detections from said detected target list.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• performing means for performing high resolution frequency measurement, phase measurement and standard deviation measurements on said FFT processed received signals;
• and
• minimizing means for minimizing ground clutter signals in said received signals in presence of target signals to improve target detection.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• performing means for performing high resolution frequency measurement, phase measurement and standard deviation measurements on said FFT processed received signals;
• and
• classifying means for classifying a detected target detected by said target signal classification process.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• performing means for performing high resolution frequency measurement, phase measurement and standard deviation measurements on data associated with Doppler resolved data filters for filtering said pre-determined received signal groups;
• and
• providing means for providing frequency domain pulse compression and Doppler correction to said received signal groups without addition and extending the integration function across all range and time bins of said group.

A pulsed Doppler radar system, comprising:

• an antenna unit;
• a transmitter for transmitting a signal through said antenna unit;
• a receiver/exciter for receiving through said antenna unit a target signal reflected by a target to provide a reception signal and for creating a reference waveform for transmitting/receiving;
• and a processing unit which receives the reception signal from said receiver/exciter and performs processing to maximize detection of the target signal;
• wherein the improvement comprises:
• architecture means for establishing an architecture that can improve system performance through systematic control of transmitter pulse recurring frequency (PRF) of said Doppler radar programmable event generator;
• performing means for performing frequency domain pulse compression and Doppler ambiguity resolution on the FFT data collected from said FFT processed received signals for a given PRF dwell period;
• performing means for performing high resolution frequency measurement, phase measurement and standard deviation measurements on data associated with Doppler resolved filters for enhanced detection processing;
• first means for providing a first processing data channel to enhance signal processing to support signal detection on pulse compressed Doppler resolved data filters;
• second means for providing a second processing data channel to enhance signal processing to support co-operative signal detection on all pulse compressed data filters;
• and
• resolving means for resolving range ambiguity on a scan to scan basis of said detected signals.