Benthos 865-A, Инструкции по установке, эксплуатации и обслуживанию

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Model 865-A Deep Sea Acoustic Release/Transponder M-855-009
Benthos, Inc.
23
The transmit frequency synthesizer is based on a 50 kHz crystal oscillator. This oscillator feeds a phase
lock loop network which synthesizes a particular frequency based on the stored value within the
microprocessor.
If the unit is ENABLED and the detector output goes true, then the pulse control circuitry allows the
transmit frequency through to the power-amplifier for 10 milliseconds. The power-amplifier consists of
two power MOSFET transistors, and a transformer steps up the AC signal to approximately 3,000
volts peak to peak. This is applied across the transducer which converts the electrical energy into
acoustic energy. The same transducer element is used for both transmit and receive.
6.3.1 Command Enable/Timed Disable Feature
The ENABLE feature prevents unwanted transmissions from occurring due to unauthorized
transponding, other sonar equipment, or random interference. Whatever the source, the result could be
a large number of unnecessary transponds by the 865-A which could result in premature battery drain.
Basically it works as follows:
The release powers up in the ENABLED state; that is, it will reply when it receives the proper
frequency. It will then remain ENABLED for the selected time, up to 255 hours (a setting of “0” hours
will disable this function, leaving the release enabled all the time). The default enable time is 12 hours
which will usually be enough time to deploy the unit and range on it (if desired). If not, the user may
simply send it an "ENABLE" command to extend (reset the timer) the enable time. Once the enable
time runs out, the transmitter portion of the release is disabled until an ENABLE command is received
or a release occurs.
NOTE: If for whatever reason the unit is not "ENABLED" when a RELEASE command is received,
the release will still take place. Upon completion of the release operation the unit will automatically
ENABLE itself so that its ascent may be tracked.
6.3.2 Backup Timer Feature
If requested at the time of order, the 865 features a BACKUP timer function that is both very powerful
and very dangerous. All standard releases are shipped with this function disabled (value set to 0).
Extreme care should be exercised whenever using this feature.
If enabled, the BACKUP timer will cause the 865 to automatically RELEASE a fixed number of hours
(up to 65,535 hours , > 7 years!) after the unit is turned on. This feature can be used in the very special
applications where a timed release function is desired. When this function is enabled, the unit will still
respond to an acoustically transmitted RELEASE command.