Abstract: A system and method for increasing the accuracy of time delay estimates of signals propagating through an environment. The system includes one or more sensors for receiving a plurality of signals, and a time delay estimator for measuring time delays between multiple pairs of signals. At least some of the multiple pairs of signals are received and measured at different points in time. The system further includes a data analyzer for analyzing time delay estimation data, for generating a statistical distribution of time delay estimates from the data, and for calculating a statistical estimate of time delay from the distribution. By increasing the number of signals employed by the system, the accuracy of the time delay estimation is increased. Further, by calculating the median or the mode of the statistical distribution, noise tolerance is improved.

Abstract: A system and method of performing sonar range estimations in a noisy sonar environment. The system includes a sensor, a transmitter, a receiver, a plurality of band-pass filters, a cross correlator, and a data analyzer. The transmitter transmits a pulse through a transmission medium. The pulse travels through the transmission medium until it strikes an object, which returns an echo to the sensor. The sensor provides the echo to the receiver, which provides an indication of the echo to the band-pass filters. The respective band-pass filters provide filtered versions of the echo and pulse to the cross correlator, which performs multiple cross correlation operations on the filtered echo and pulse. The cross correlator provides output data to the data analyzer, which uses the data to estimate the SNR in the environment and to determine a pulse center frequency corresponding to the estimated SNR.

Abstract: Explosive gas detectors are functionally tested by directing a brief aerosol spray discharge of a formulation selected to provide a visible spray discharge and from an aerosol dispenser pressurized with a hydrocarbon propellant. The propellant activates a properly functioning gas detector. The visible directional spray visually confirms delivery of propellant to the gas detector unit, so that a failure to activate is properly attributable to detector failure. A preferred formulation is one previously proven successful for the functional testing of electronic smoke detectors.

Abstract: A method and kit of parts for testing heat detectors mounted at an elevated location above a ground surface using a supercorrosive metal alloy composition formulated to react exothermically but non-flammably upon being wetted for sustaining temperatures of about 195 degrees Fahrenheit, permitting testing of heat detectors rated at 175 to 195 degrees F. The composition is formed into convenient wafers which are elevated on an extension pole into proximity to the heat detector by an operator standing on the ground. The wafers may be activated by wetting with a disposable plastic syringe, and may be reheated several times.

Abstract: An improved aerosol formulation for activating a smoke detector by emulating the effects of combustion products to test smoke detectors includes a propellant and an active ingredient consisting of one or more linear alkyl phthalate esters characterized by linear carbon chains of either seven or nine carbons in length, the alkyl phthalate esters being present in a proportion of between 10% and 1%.