Abstract: An acoustic device for forming a wall of sound underwater. Walls of sound are useful in water for guiding fish away from areas. Hitherto, systems have used bubbles of water to facilitate the speed of travel of the sound. Those systems have suffered from the ability to maintain a consistent wall of bubbles and have often been inefficient. The present invention seeks to provide an acoustic device for forming a wall of sound underwater and comprises a transducer connected to an acoustic waveguide. The waveguide comprises one or more projections, whereby sound generated by the transducer travels along the projection or projections to form the wall of sound. The waveguide may typically comprise compressible projections formed from neoprene. These projections are arranged in a fan or frond shape. In addition or alternatively, the projections may be laminar. The projections could be of different lengths.

Abstract: The present invention relates to a device for determining the characteristic impedance spectrum of a token such as a monetary coin, said device comprising: —a point impedance transducer having an inducing element for inducing an ultrasonic movement in the token and a sensing element for detecting the resistance of the token to that induced movement; —a closed system for housing said point impedance transducer; and processing means connected to the point impedance transducer for determining the characteristic impedance spectrum of said token. In particular, the present invention relates to testing whether a token or coin is genuine or a forgery, of sorting coins including from differing monetary systems and/or their denominations, and also providing a “fingerprint” for forged coins.

Abstract: An acoustic device for forming a wall of sound underwater. Walls of sound are useful in water for guiding fish away from areas. Hitherto, systems have used bubbles of water to facilitate the speed of travel of the sound. Those systems have suffered from the ability to maintain a consistent wall of bubbles and have often been inefficient. The present invention seeks to provide an acoustic device for forming a wall of sound underwater and comprises a transducer connected to an acoustic waveguide. The waveguide comprises one or more projections, whereby sound generated by the transducer travels along the projection or projections to form the wall of sound. The waveguide may typically comprise compressible projections formed from neoprene. These projections are arranged in a fan or frond shape. In addition or alternatively, the projections may be laminar. The projections could be of different lengths.

Abstract: The present invention relates to a device for determining the characteristic impedance spectrum of a token such as a monetary coin, said device comprising:—a point impedance transducer having an inducing element for inducing an ultrasonic movement in the token and a sensing element for detecting the resistance of the token to that induced movement;—a closed system for housing said point impedance transducer; and processing means connected to the point impedance transducer for determining the characteristic impedance spectrum of said token. In particular, the present invention relates to testing whether a token or coin is genuine or a forgery, of sorting coins including from differing monetary systems and/or their denominations, and also providing a “fingerprint” for forged coins.

Abstract: In order to deter underwater animals from an underwater region such as adjacent the entrance to an offtake pipe or channel from a river, sound and light are produced by sound and light producing units in the underwater region and are intermittently pulsed and/or at least one characteristic of the sound and light is repetitively modulated. At least some of the pulses of light and/or the occurrences of at least one feature in at least some of the light modulation repetitions are substantially synchronised with at least some of the pulses of sound and/or the occurrences of at least one feature in at least some of the sound modulation repetitions. For example, the sound may be frequency modulated, and the light may be pulsed when the sound frequency reaches its minimum. It is believed that this synchronisation of light and sound has a synergistic effect.

Abstract: A distance measuring system is described which may be used as an altimeter for a helicopter or for a load carried by its winch. The system comprises: a transmitting transducer for converting a first modulated electrical signal into a corresponding acoustic signal to be directed towards and reflected by a surface; a receiving transducer for converting the received reflected acoustic signal into a corresponding second electrical signal; and a correlation processor for receiving the second electrical signal, or the first and second electrical signals, and correlating the modulations thereof to produce an indication of a time delay thereof from which the distance travelled by the acoustic signal can be determined.

Abstract: A distance measuring system is described which may be used as an altimeter for a helicopter or for a load carried by its winch. The system comprises: a transmitting transducer for converting a first modulated electrical signal into a corresponding acoustic signal to be directed towards and reflected by a surface; a receiving transducer for converting the received reflected acoustic signal into a corresponding second electrical signal; and a correlation processor for receiving the second electrical signal, or the first and second electrical signals, and correlating the modulations thereof to produce an indication of a time delay thereof from which the distance travelled by the acoustic signal can be determined.

Abstract: An apparatus for dislodging or loosening mucus in a person's lungs, for example of a sufferer of cystic fibrosis, comprises a bath arranged to receive the person and filled with water such that the person's chest is immersed in the water. A vibrator vibrates the liquid so that the vibrations are transmitted to the person's lungs. In use the vibrations are preferably at the pulmonary resonant frequency or Helmholtz resonant frequency of the person's lungs.