Abstract: The invention automatically detects a gunshot at a plurality of detection and response nodes distributed in an area, determines the location of the active shooter, and deploys a suppression response to the location of the active shooter from each of the plurality of detection and response nodes to prevent the active shooter from firing further gunshots.

Abstract: Disclosed herein is a design, simulation, and hardware build of a photonic compressed sensing Nyquist folding receiver that is able to directly undersample wideband RF signals and detect the original Nyquist zone and frequency information. According to an exemplary embodiment, this is achieved by generating a frequency modulated optical impulse train for directly undersampling the RF environment at the antenna. The impulse train undersamples the signals using an optical modulator configuration at 1550 nm and collects the detected samples in a low pass interpolation filter which is subsequently processed to extract the undersampled signals.

Abstract: Disclosed is a method, system, and apparatus for transmitting a randomly phase-coded CW waveform in a manner that suppresses signal leakage and enables the recovery of polyphase subcodes advantageous for the purposes of correlation and pulse compression. The CW system transmits and receives a random waveform while concurrently providing properly delayed phase conversion parameters (?i??i) from a corrections generator to various range gates. Each range gate processes any echo returns using a most recent phase conversion parameters (?k??k) provided and correlation of the resulting echo subcodes ?R produce either target indications or noise signals, depending on the most recent phase conversion parameters (?k??k) provided to the range gate. The system may transmit the randomly phase-coded CW waveform while recovering any phase code {?1, ?2, . . . ?N} that lends itself to advantageous pulse compressions.

Abstract: Disclosed is a method, system, and apparatus for transmitting a randomly phase-coded CW waveform in a manner that suppresses signal leakage and enables the recovery of polyphase subcodes advantageous for the purposes of correlation and pulse compression. The CW system transmits and receives a random waveform while concurrently providing properly delayed phase conversion parameters (?i??i) from a corrections generator to various range gates. Each range gate processes any echo returns using a most recent phase conversion parameters (?k??k) provided and correlation of the resulting echo subcodes ?R produce either target indications or noise signals, depending on the most recent phase conversion parameters (?k??k) provided to the range gate. The system may transmit the randomly phase-coded CW waveform while recovering any phase code {?1, ?2, . . . ?N} that lends itself to advantageous pulse compressions.

Abstract: The invention automatically detects a gunshot at a plurality of detection and response nodes distributed in an area, determines the location of the active shooter, and deploys a suppression response to the location of the active shooter from each of the plurality of detection and response nodes to prevent the active shooter from firing further gunshots.

Abstract: Disclosed herein is a design, simulation, and hardware build of a photonic compressed sensing Nyquist folding receiver that is able to directly undersample wideband RF signals and detect the original Nyquist zone and frequency information. According to an exemplary embodiment, this is achieved by generating a frequency modulated optical impulse train for directly undersampling the RF environment at the antenna. The impulse train undersamples the signals using an optical modulator configuration at 1550 nm and collects the detected samples in a low pass interpolation filter which is subsequently processed to extract the undersampled signals.

Abstract: A four-element wideband photonic DF system with robust symmetrical number system preprocessing utilizes dual electrode Mach-Zehnder modulators (DE-MZMs) to conduct phase detection for direct wideband direction finding (DF) of RF signals, such as microwave signals, in which the normalized magnitude of the output signal phase detector circuit is equal to |sin(?/2)| where ? is the phase difference between the plane waves arriving at the reference and measurement antennas of a linear DF array. The method and system allow fine angular resolution using a much smaller array size than is typically required for linear arrays employing super-resolution signal processing techniques.

Abstract: A method and apparatus for automatically determining a hazardous environmental condition within a container, such as a vehicle, and initiating alarm devices. In one embodiment, temperature, motion, acoustic, and pressure sensors in a vehicle output sensor signals to associated sensor threshold monitors. When a sensor threshold is exceeded, a sensor threshold monitor sends a threshold signal to a sensor collection logic device. The sensor collection logic device determines whether to initiate an alarm process based on whether the threshold signals indicated a hazardous environmental condition within the vehicle. In one embodiment, upon a determination to initiate the alarm process, the sensor collection logic device sends an alarm signal to an alarm processor which automatically initiates output signals to alarm devices, such as an audible alarm.

Abstract: Embodiments in accordance with the invention allow for direct digitization of wideband RF signals without the need for down conversion or the use of mixers. In one embodiment, a preprocessed input analog signal is applied to three wideband Mach-Zehnder interferometers (MZI), e.g., modulators, to amplitude modulate a continuous wave laser signal. A photodetector is used at the output of each interferometer to convert the amplitude modulated optical signal into an electrical signal. This is followed by an amplifier and a low-pass filter (LPF) to increase the signal level and to reduce the noise. A small mi comparator bank at the output of each LPF is clocked at the sampling frequency and encodes the electrical signal from each detector into a thermometer code that represents an integer value within the modulus. A field programmable gate array (FPGA) then combines the thermometer-code from each comparator bank in order to generate a more convenient 6-bit binary representation, i.e., a digital output.

Abstract: A digital synthesizer includes a digital radio frequency memory (DRFM) for storing phase values and corresponding digital signals. The digital synthesizer includes a digital processing circuit receiving input from the DRFM, the circuit including tapped delay lines and a summer summing the output of the tapped delay lines. The digital synthesizer includes a signal modulator independently synthesizing within each tapped delay line a frequency modulated and gain scaled signal, wherein input to the tapped delay lines are phase values from the DRFM.

Abstract: A method and system for signal processing, especially useful as a signal repeater, i.e. for simulating the characteristic echo signature of a preselected target. The system has a digital radio frequency memory (DRFM) and associated circuitry, including digital tapped delay lines, and a modulator in each delay line to impose both amplitude and frequency modulation in each line.

Abstract: A method and system for signal processing, especially useful as a signal repeater, i.e. for simulating the characteristic echo signature of a preselected target. The system has a digital radio frequency memory (DRFM) and associated circuitry, including digital tapped delay lines, and a modulator in each delay line to impose both amplitude and frequency modulation in each line. Use of digital semiconductor technology increases the bandwidth and sensitivity of such a repeater over prior analog based systems, reduces the noise of the repeated signal, reduces size and cost of such a system, and permits real time alteration of operating parameters, permitting rapid and adaptive shifting among different kinds of targets to be simulated. Preferably the associated circuitry is unitary with, and part of, the DRFM.

Abstract: A system for generating a false target radar image for countering wideband synthetic aperture and inverse synthetic aperture imaging radar systems to prevent a selected target from being detected by such radar systems comprises a receiver system for producing a digital signal that represents an incident radar signal. A phase sampling circuit is connected to the receiver for sampling the digital signal and providing phase sample data. An image synthesizer circuit is connected to the phase sampling circuit and arranged to receive the phase sample data therefrom. The digital image synthesizer circuit is arranged to process the phase sample data to form a false target signal, which is input to a signal transmitter system arranged to transmit the synthesized false target signal so that it can be received by a radar system.

Abstract: An antenna receives an analog waveform and an analog signal indicative of the amplitude and frequency of the analog waveform. The analog signal is processed in a plurality of parallel digital processing channels each arranged to digitize the analog signal at a corresponding sampling frequency f.sub.si to produce a plurality of digital signals. A discrete Fourier transform is applied to each of the digital signals output to produce a corresponding plurality of unique Fourier spectra of length m.sub.i =(f.sub.si)(T.sub.Li) where T.sub.Li is the integration time for the discrete Fourier transform for each digital processing channel. The lengths of the Fourier spectra (m.sub.i) are selected to be pairwise relatively prime. The discrete Fourier transform encodes the signals in same form as the symmetrical number system (SNS). A SNS-to-decimal algorithm is then applied to the detected bin values (a.sub.i) to determine the numerical value of the frequency f of the analog waveform.

Abstract: An analog-to-digital converter in which an analog input signal is folded by a plurality of folding circuits whose moduli, and hence half folding periods, are mutually prime with respect to one another. Each folding circuit has an associated comparator ladder having one less comparator than the modulus of the folding circuit. The collective output of the ladders, i.e. the states of the comparators in the ladders, uniquely corresponds to input signal magnitude over a dynamic range equal to the product of the folding circuits' moduli, permitting a greater dynamic range for the converter for the number of comparators used.