Esonet Yellow Pages

The Type 8048-000-03 Programmable Deep Oceanographic Release Transponder (P-DORT) combines the features of a heavy duty acoustic release transponder with hardware to allow automatic release at depth.
The P-DORT has two modes of basic operation. Firstly, like a standard DORT, it responds to securely coded acoustic commands from the surface in the LF (9-13 kHz) frequency band.
Secondly, it can be pre-programmed prior to deployment to automatically release when it reaches a certain depth. This allows heavy items, such as submarine cables for example, to be lowered precisely to the seabed and then the lowering apparatus recovered after an automatic release. The acoustic ranging function within the P-DORT can also be used to relocate the equipment should the lowering cable fail.
There are two options for setting the 'release at depth' option. In the primary mode, a depth is set and once the unit passes that depth, the unit will immediately release. The secondary mode allows for shallower depth to be set for when the primary release depth has been erroneously set to greater than the actual water depth. Then, if the unit passes that depth but remains stationary (i.e. on the seabed) for a specified time, it will release.
The Windows-based control software for the automatic depth mode runs on a standard PC running Windows 98, ME, 2000 or XP and is connected to the P-DORT using a serial cable and interface box.