Abstract: An underwater weapon system comprises an elongate outer container which is buried or partially buried in the sea bed in an upright position using devices at the bottom end of the container and which preferably comprise both a pump for removing sand or silt and an auger for boring a hole in the sea bed or a rotary stirrer. The weapon is a self-propelled device with guidance and is housed within an inner container which is telescopically arranged within the outer container.

Abstract: A circuit for providing an indication of the signal/noise ratio of a single frequency signal as received by a receiver has first and second signal paths extending from its input to a comparator contained in the circuit. The first signal path includes a narrow band-pass filter, while the second signal path includes a notch filter. Means are provided in each signal path, for integrating the output of the respective filter. The comparator compares the outputs of the integrating means and outputs when the output of the first signal path integrating means is equal to or greater than the output of the second signal path integrating means. The time which elapses between the receipt of the signal at the input and the beginning of the comparator's output provides an indication of the signal/noise ratio. Such circuits can be used in selecting receivers in multi-receiver arrangements.