Abstract: A method and apparatus for generating, propagating, encoding, decoding, modulating and detecting acoustic signals in a well borehole that comprises a signal generator (10) located at a first location for generating an acoustic source signal; a medium for the propagation the acoustic source signal to a second location and the propagation of the reflections and partial reflections of acoustic signals as it propagates through the medium; an apparatus to remove a detectable amount of energy from propagated acoustic signals; a controllable signal modulator (11) for attenuating the transmitted acoustic source signal; and a receiver (12) for receiving the modulated acoustic signals reflected, partially reflected or both by at least one reflector respectively located at one or more other locations.

Abstract: A safety attachment (10) for being releasably mounted on the spoked wheel (16) of a vehicle such as a bicycle for enhancing the visibility of the vehicle and/or decorating the vehicle is disclosed. The attachment (10) comprises a display panel (12) for being releasably mounted between the spokes (14) radiating from the opposite end portions of the hub (32) of the wheel (16), the display panel (12) defining oppositely disposed display surfaces (18, 20). The panel (12) further defines an outer edge portion (22) which is positioned proximate the rim (24) of the wheel (16) between the converging spokes (14), and an inner portion (26) positioned proximate the hub (32) of the wheel (16). The attachment (10) further comprises spring biased fastening means (28) for releasably securing said display panel (12) in position between the spokes (14).