Sonardyne UK (Head Office) T. +44 (0) 1252 872288 F. +44 (0) 1252 876100 E. [email protected] www.sonardyne.com Datasheet Acoustic Switch Transponder (AST) 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. 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. Description The AST is compatible with LF versions of Sonardyne transceivers such as the PAN, RovNav and LCU (Lightweight Command Unit). Key features • High reliability • Secure command system • Ranges up to 10,000 Metres • Contact closure for 4 seconds • Long listening life Sonardyne UK (Head Office) T. +44 (0) 1252 872288 F. +44 (0) 1252 876100 E. [email protected] www.sonardyne.com Specifications Acoustic Switch Transponder (AST) Feature Type 7904 Depth Rating 3,000 Metres Operating Frequency LF (7.5kHz-15kHz) Transceiver Frequency 13.26kHz Transceiver Pulse Length 10ms Transceiver Source Level (re 1µPa @1m) 190dB Alkaline/184dB Lithium Transceiver Beam Pattern Hemispherical Receiver Frequencies 7.5 - 12.5kHz Receiver Sensivity (re 1µPa) <95dB Quiescent Life 9 months Alkaline/ 24 months Lithium Shelf Life (Battery Disconnected) stored at 25ºC 24 months Alkaline/ 84 months Lithium Mechanical Construction Hard Anodised Aluminium Alloy Operating Temperature -10 to +45ºC Storage Temperature -30 to +70ºC Weight in Air 12kg Weight in Water 6kg Specifications subject to change without notice - 10/2006