Specifications

BATS AND PORTABLE BATS OPERATION
3-31
actual slant range from the target the system shows an error code #7 (SR < Min Range). After 5
interrogations without a reply the system opens up the blanking gate and accepts the reply on the
sixth (6th) interrogation (EC #6 may appear briefly prior to reception of signal). If the Slant Range
is less than the Slant Range Limit’s (from value) then the error code #6 is changed to #7. The
Slant Range Limit’s (from value) can vary from 1 to 1000 meters.
NOTE: If you are operating with a known minimum range, for example with an ROV near the
bottom in 500 meters of water, then the Slant Range Limit’s (from value) could be set
for 450 meters. This would provide an effective "range gate" without the attendant tar-
get acquisition and re-acquisition time of the normal range gate. Of course, as you re-
cover the ROV you will have to reset the Slant Range Limit’s (from value) to track the
ROV to the surface.
The Slant Range Limit’s (to value) (Maximum Slant Range) function compares the reply’s slant
range against this value. If the slant range is greater than the entered value the last good reply
remains on the display (target position on the screen doesn’t change) and the status block shows
an error code #14. If the RS232 Format is set to an “EC” format it also outputs the last good posi-
tion and tags it with an error code #14. The Slant Range Limit’s (to value) can vary from 0 m
which is OFF to 10 to 10000 meters.
The BEARING LIMIT function is a final check after the range gate and velocity filter are satisfied.
The system checks to see whether the target is within the parameters as set by the bearing limits.
This function is only applicable to targets with a depression angle of less than 45. If a target is
outside the set limits then the system displays an error code #15, "BEARING LIMIT EXCEEDED".
The system does not update the target on the screen but the data is sent out the RS232 (when an
“EC” format is selected) with the fatal error #15 attached to the string. The limits are always refer-
enced to the vessel, whether compass mode is ON or OFF. The default values for the bearing limits
are 0 to 0, which disable the function.