Sonardyne UK (Head Office)
T. +44 (0) 1252 872288
F. +44 (0) 1252 876100
E. [email protected]
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
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]
Acoustic Switch Transponder (AST)
Type 7904
Depth Rating
3,000 Metres
Operating Frequency
LF (7.5kHz-15kHz)
Transceiver Frequency
Transceiver Pulse Length
Transceiver Source Level (re 1µPa @1m)
190dB Alkaline/184dB Lithium
Transceiver Beam Pattern
Receiver Frequencies
7.5 - 12.5kHz
Receiver Sensivity (re 1µPa)
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
Weight in Water
Specifications subject to change without notice - 10/2006