Benthos 865-A - 1 Introduction

Model 865-A Deep Sea Acoustic Release/Transponder M-855-009
Benthos, Inc.
1
1.0 INTRODUCTION
This manual describes the use and operation of the standard Model 865-A Deep Sea Acoustic
Release/Transponder, that have the microprocessor based board set, A-855-170. The unit, shown in
figure 1.1 Outline Drawing, is designed for long range, heavy duty, deep or shallow water applications.
It can support a load of 10,000 pounds (4540 Kg) and is tested to a simulated depth of 12,000 meters
prior to leaving the factory. It is primarily intended to be used as the release link for the recovery and
relocation of moored instrument arrays (see Figure 1-2). For ease of location and measurement of slant
range, the unit will transpond when interrogated at a predetermined frequency.
Upon recovery, the release can be easily and externally recocked for repetitive deployment. The
standard battery pack will easily provide 2 years use, with many releases and a minimum of 250,000
transponds.
Interrogations and commands are transmitted by the Model DS-7000 Deck Unit, which also provides a
four-digit readout of slant range up to 10,000 meters. The deck unit provides seventeen different
interrogate frequencies and eight different command codes per receiver frequency, so that location and
ranging can be carried out on many deployed Release/Transponders without interaction. The Model
DS-7000 Deck Unit has its own manual and is not described in detail here.
Upon completion of a RELEASE command, the 865-A will change its transponder reply from one to
five pings for every interrogate pulse from the deck unit. At the deck unit the verification that the
RELEASE command has been received and acted upon is seen as a series of flashes from the receiver
LED when the proper receive frequency is selected. The 865-A reverts to a single ping when the unit is
recocked.
In order to ensure the maximum battery life of the 865-A, there is an integral transpond enable/disable
feature. After a predetermined time, the transpond capability is automatically disabled. This prevents
unintended pings, which would waste energy. By sending an ENABLE command the timer is reset and
the release will again reply when interrogated.