Model 865-A Deep Sea Acoustic Release/Transponder M-855-009
Benthos, Inc.
13
Note that the 865-A will not respond to transmissions within 1.5 seconds of each other. This is
the standard LOCKOUT feature which prevents extra replies from multipaths.
Also note that if the ENABLE time has run out, the 865-A will not reply at all. (See Section
6.3.1.)
c. Change the Tx Frequency selected on the deck unit and now verify that the unit DOES NOT
reply when interrogated. The unit should only respond to the proper frequency.
4.2.3 Command Enable
To test the ENABLE feature, leave the release ON-ARMED until the Enable Timer runs out. This may
take 12 hours, depending on value selected. Then verify that it will not reply when interrogated. Place
the deck unit transducer very close to the 865-A, similar to Figure 4-2.
Next send an ENABLE command and afterwards verify that the unit will reply when interrogated. To
send a command, follow these steps:
a. Set the TRANSMIT FREQUENCY (Tx) on the deck unit to the receive frequency of the 865-A
being commanded, as in 4.2.2a.
b. In the Command Mode, select the letter codes designated on the 865-A for ENABLE.
c. Send a command. During the middle of the command you may hear the 865-A ping once as it
"wakes up".
d. Send a single transpond and verify that the ENABLE command was successful, i.e. the 865-A
does reply. If not, move the deck unit transducer slightly and try another command.
NOTE: It is sometimes very difficult to get a command through the air. If you have trouble, do
not panic! This is normal, as the system is designed to operate in water where the sound paths
are more predictable. Simply move the transducers to slightly different positions, often a change
of as little as one inch (1") is all that is necessary to make the difference. It may be helpful to line
the test area with foam rubber to dampen reverberations.
Because of the long wait for the ENABLE timer it is not necessary to test this feature routinely.
However, it is recommended that you test it at least once so that you are completely familiar with
its operation.
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