Abstract: An acoustic transponder provides information related to the transponder when the transponder is receiving an acoustic interrogating signal. The transponder includes a power supply, an electronic circuit connected to the power supply, and one or more transducers receiving and emitting the acoustic signal. The electronic circuit includes a sequence generator. The transponder further includes an amplification and modulation unit, an extraction filter, and a suppression filter. The extraction filter is adapted to extract the received acoustic interrogating signal and suppress other signals prior to being input to the amplification and modulation unit which are configured to modulate the received acoustic signal according to a sequence generated by the sequence generator and to amplify the modulated signal. The suppression filter is adapted to suppress the received acoustic interrogating signal from the amplified and modulated signal.

Abstract: An acoustic transponder provides information related to the transponder when the transponder is receiving an acoustic interrogating signal. The transponder includes a power supply, an electronic circuit connected to the power supply, and one or more transducers receiving and emitting the acoustic signal. The electronic circuit includes a sequence generator. The transponder further includes an amplification and modulation unit, an extraction filter, and a suppression filter. The extraction filter is adapted to extract the received acoustic interrogating signal and suppress other signals prior to being input to the amplification and modulation unit which are configured to modulate the received acoustic signal according to a sequence generated by the sequence generator and to amplify the modulated signal. The suppression filter is adapted to suppress the received acoustic interrogating signal from the amplified and modulated signal.

Abstract: A semi-passive acoustic transponder providing identity information related to the transponder when it is reflecting a received pulsed acoustic signal underwater. The transponder includes a memory unit holding ID-sequence data controlling operation of the switching device, and an electronic circuit includes frequency adjusting means for adjusting the frequency and duration of the switch such that the duration of the ID-sequence data is shorter than the duration of pulses of the received acoustic signal. Additionally, a method and system may provide position and identity information related to one or more of said semi-passive acoustic transponders.

Abstract: A semi-passive acoustic transponder providing identity information related to the transponder when it is reflecting a received pulsed acoustic signal underwater. The transponder includes a memory unit holding ID-sequence data controlling operation of the switching device, and an electronic circuit includes frequency adjusting means for adjusting the frequency and duration of the switch such that the duration of the ID-sequence data is shorter than the duration of pulses of the received acoustic signal. Additionally, a method and system may provide position and identity information related to one or more of said semi-passive acoustic transponders.