Specifications

BATS AND PORTABLE BATS OPERATION
3-30
aging is almost linear across all replies while at the lower filter levels the weight is higher on the
most recent reply. Averaging occurs on the target's position only (X, Y or HD, BRG), not on the
displayed slant range. The slant range displayed in the status block and sent out the RS-232 is the
actual value. Because of this there may be an apparent discrepancy between the displayed posi-
tion and slant range.
QF Filtering: QF Filtering is a toggle function that turns QF Filtering on or off. The Quality Factor
(QF) is a value (1-10) determined by the system on each reply that is detected. The system uses
the phase or time counts from each of the hydrophone elements to determine the quality of the
signal. If the phase counts are consistent throughout the reply burst the quality factor is very high.
If the phase counts have jitter or are inconsistent then the quality factor is low. The QF FILTERING
function filters the data depending on the Quality Factor of the signal received. It compares the
Quality Factor of the signal received to its previous five (5) average Quality Factors. The QF FIL-
TERING function toggles Quality Factor checking on or off.
This function filters the data depending on the Quality Factor of the signal received. When “QF FIL-
TERING” is “ON” and the Quality factor is less than the average of the last five QF’s the data is not
plotted and causes an error code #4 to be displayed. In this case the error is considered a “fatal”
error (similar to all other error codes under 20) and the reply is not added to the smoothing buffer.
The target position is not updated on the screen and the positional data is not sent out the RS232
port unless the “EC” formats are chosen. If “EC” formats are chosen then a post processing naviga-
tion system could be used to determine if the reply was good or bad by searching for a 4 at the EC
location within the data string. When “QF FILTERING” is “OFF” and the Quality factor is less than
the average of the last five QF’s the data is plotted on the screen and sent out the RS232. The data
is tagged with an error code #64 on both the display and RS232. In this case the error is consid-
ered a “warning” error (similar to all other error codes greater than 50). The data is still smoothed
but its “weight” within the averaging buffer is decreased. Again, a post processing navigation sys-
tem could then be used to determine if the reply was good or bad by searching for a 64 at the EC
location within the data string.
Maximum Target Velocity: Select the Maximum Target Velocity (+/-) if using a PRN or Remus
type codes (as they are susceptible to Doppler shift). If the target, for example, is a towfish (which
has very little relative movement between target and Hydrophone) the MTV can be kept at 5 knots
or less. By keeping the MTV below 5 knots the processing load on the Transceiver is minimized.
Target Limits: The Slant Range Limit (Minimum Transponder or Responder Range) function works
in conjunction with the range gating (blanking) system based on the target slant range. The range
(blanking) gate is a hardware lockout that “opens up” and allows signals to be detected from the
hydrophone. The time that the blanking gate opens is based on the Filter Level and the time the
last reply was received. If a condition occurs where the blanking gate end time is less than the
Slant Range Limit’s (from value) then the blanking gate overrides the Slant Range Limit’s (from
value). This in effect locks-out all signals from the hydrophone prior to the end of the blanking
gate. If the system loses tracking due to the Slant Range Limit (from value) being greater than the