Abstract: A plurality of sensors and a digital adaptive tuning filter bank are used in extracting a desired emitted signal embedded in a noisy environment. By monitoring noise statistics of the sensor signals, the digital adaptive tuning filter bank automatically adjusts its upper (to eliminate strong tonals) and lower (to eliminate background noise) thresholds to obtain a discovery frequency band. The filter bank is designed by examining the discovery band across the sensors and over a predefined period of time. The method described significantly reduces the possibilities of matching self-noise transients (unwanted signals) and thus minimizes the false alarm rate in emitted signal recognition.

Abstract: A system and method are provided for improving spectrum linewidth and stability while using the lasing region of a conventional laser diode light source. The inventive system and method provide a dithering signal for varying the drive current of the laser diode light source. By varying the drive current, the spectrum linewidth and stability of the conventional laser diode light source is significantly improved. Specifically, an optic fiber gyroscope can be driven by a conventional laser diode source which is powered by a dithered drive signal.

Abstract: A system and method are provided for improving spectrum linewidth and stability while using the lasing region of a conventional laser diode light source. The inventive system and method provide a dithering signal for varying the drive current of the laser diode light source. By varying the drive current, the spectrum linewidth and stability of the conventional laser diode light source is significantly improved. Specifically, an optic fiber gyroscope can be driven by a conventional laser diode source which is powered by a dithered drive signal.

Abstract: A method for testing students comprises updating a database in a host computer by entering relevant user information, establishing wave energy communication between the host computer and a plurality of a handheld device, registering user presence by entering user identification information in the handheld devices, presenting a set of test questions comprising a test to the handheld devices from the host computer, receiving answers to the test questions, analyzing individual test results, group test results, and accumulated test results for each individual one of the handheld devices and groups of the handheld devices.

Abstract: A fiber optic gyroscope for measuring a rotation rate of an object. The gyroscope includes a light source for generating a light beam and a bidirectional coupler for receiving and forwarding the light beam. A splitter splits the light beam forwarded from the coupler into a first beam and a second beam. A fiber optic coil receives the first and second beams and a phase modulator adjusts the phase of the first and second beams. A signal processor determines the rotational rate of the gyroscope based on the phase difference between the first and second beams. A drive circuit drives the phase modulator to adjust the phases of the first and second beams if the rotation rate of the gyroscope exceeds a certain threshold.

Abstract: The linearity of a fiber optic gyroscope can be improved by dithering the gyroscope's feedback signal. An output signal can be taken over any time interval by sampling the feedback signal before dithering is applied.

Abstract: A method for measuring the rise/fall time and pulse width of RF pulses using multi-purpose, commercial-off-the-shelf test devices, such as an RF signal down converter, a digitizer and a signal processor. The method is based on digitizing the RF signals and developing an average sample pulse waveform. The rise/fall time and pulse width are then calculated from data points on the sample waveform. The method is suitable for real-time calculations of the rise/fall time and pulse width.

Abstract: A low-cost gyroscope can provide an output approaching the accuracy of more precise instruments by processing the gyroscope output signal. First, a calibration algorithm develops a set of coefficients to predict drift. Second, an adaptive operational algorithm updates the coefficients during periods of inactivity and filters out high and low frequency noise components. An accurate, low-cost, rugged aiming device for a weapon can be realized with a simple, relatively-inexpensive gyroscope by utilizing the foregoing algorithms.

Abstract: The linearity of a fiber optic gyroscope can be improved by dithering the gyroscope's feedback signal. Any undesirable effects introduced by the dithering signal are removed by processing the gyroscope data over an entire cycle of the dithering signal. A further improvement in linearity can be achieved by introducing a compensation signal.

Abstract: A method for measuring the frequency of continuous wave and wide pulse RF signals using multi-purpose, commercial-off-the-shelf test devices, such as an RF signal down converter, a digitizer and a signal processor. The method is based on digitizing the RF signals and dividing the digitized data into blocks of discrete data points. An initial estimated frequency is calculated for the first block of data and used to generate a synthetic signal. The synthetic signal and individual block of data under analysis are summed and tested by a discrimination function through an iteration process to arrive at an estimated frequency for each block of data points. The results are averaged to arrive at the final calculated frequency for the RF signal. The method is suitable for real-time calculations of the RF signal frequency.

Abstract: A method for measuring the frequency of a stream of RF pulses using multi-purpose, commercial-off-the-shelf test devices, such as an RF signal down converter, a digitizer and a signal processor. The method is based on digital signal processing and determining the zero-crossings of the signal using signal interpolation of the pulse points. The method is suitable for real-time calculations of the frequency.

Abstract: A method for characterizing frequency modulation rate parameters for a swept frequency signal is based on zero crossing counting and digital signal processing. The method is easy to implement and does not require batch processing so as to be suitable for real time tracking of frequency variations in a variety of applications.

Abstract: A sequence of n sample values occurring during a recording interval is processed by determining which of the sample values is the smallest and which of them is the largest. The smallest sample value is loaded into one of first and second memory portions in dependence upon whether the smallest value occurred before or after the largest sample value, and the largest sample value is loaded into the other of the first and second memory portions. In this fashion, the order of the smallest and largest sample values is preserved.

Abstract: Traditionally, the parameters evaluation and characterization of amplitude modulation(AM), frequency modulation(FM) and phase modulation(.phi.M) signals are achieved utilizing analog test and measurement instruments. The advancement of high speed analog to digital converters and digital signal processing techniques have made this digital AM/FM/.phi.M demodulator an accurate, repeatable and cost effective alternative for the test and measurement of various modulation waveforms. This invention illustrates the design of the digital AM/FM/.phi.M demodulator.

Abstract: A method and apparatus are disclosed which provide for the removal of distortion present in a digital output signal from a linear analog signal processing system. Two applications are disclosed: digital compensation and digital equalization. Digital compensation provides for the removal of distortion from a single signal processing system. In particular, an adaptive digital filter operates to provide processing of an output signal from the signal processing system in accordance with correction criteria determined by a controller in response to a training signal. Digital equalization is employed with respect to a plurality of signal processing systems, and provides equalization of an output signal from one signal processing system in accordance with characteristics of a selected signal processing system.