7904

Sonardyne UK (Head Office) T. +44 (0) 1252 872288 F. +44 (0) 1252 876100 E. sales@sonardyne.com www.sonardyne.com Datasheet Acoustic Switch Transponder (AST) Description The Type 7904 Acoustic Switch Transponder (AST) has been designed to provide AUVs and ROVs with an emergency system which can operate independent of all other systems. Reception of a sequence of acoustic commands causes a contact closure within the AST which can be used, for example, to release a weight, causing the vehicle to rise to the surface. An acoustic command is sent from a Sonardyne surface system to arm the actuation system. A second, different command must be received within a defined time limit in order for the contact closure to operate. The contact remains closed for 4 seconds and then opens again. This command method has been successfully used for subsea valve operations over many years and provides a high degree of security against accidental actuation. Key features • High reliability • Secure command system • Ranges up to 10,000 Metres • Contact closure for 4 seconds • Long listening life The AST operates in the Low Frequency (LF) band for maximum range and independence from the majority of acoustic navigation systems. The acoustic parameters of the AST are set to allow ranges up to 10,000 metres in suitable environmental conditions. A further command allows the range of the AST to be determined without actuating the device. This can be useful in guiding the surface vessel over the vehicle both before and after actuation, assisting recovery operations. The AST is compatible with LF versions of Sonardyne transceivers such as the PAN, RovNav and LCU (Lightweight Command Unit). Sonardyne UK (Head Office) T. +44 (0) 1252 872288 F. +44 (0) 1252 876100 E. sales@sonardyne.com www.sonardyne.com Specifications Acoustic Switch Transponder (AST) Feature Depth Rating Operating Frequency Transceiver Frequency Transceiver Pulse Length Transceiver Source Level (re 1µPa @1m) Transceiver Beam Pattern Receiver Frequencies Receiver Sensivity (re 1µPa) Quiescent Life Shelf Life (Battery Disconnected) stored at 25ºC Mechanical Construction Operating Temperature Storage Temperature Weight in Air Weight in Water Type 7904 3,000 Metres LF (7.5kHz-15kHz) 13.26kHz 10ms 190dB Alkaline/184dB Lithium Hemispherical 7.5 - 12.5kHz