Pulse Type; Vari-Swath - Teledyne SeaBat T Series Operator's Manual

ACTIVE SONAR USAGE
6.2.6.1 Pulse Length and Image Resolution
For a given power setting, a narrower pulse length will provide a higher resolution at a shorter
range. A wider pulse length will provide better range but a lower resolution image.
In certain conditions, for example in turbid waters, the narrower pulse length may not operate
well. In such circumstances, the wider pulse length may give better short-range performance.
This may also be achieved by changing from higher to lower frequency operation.
6.2.6.2 Pulse Length and Pulse Type
The pulse length setting depends on pulse type (see section 6.2.7 below).
 In CW mode, typically set Pulse Length at 30µs (range is 30µs-300µs), and increase
with Range. The shorter the pulse in CW mode, the higher the resolution. The longer
the pulse, the greater the range performance but the lower the resolution.
 In FM mode, typically set Pulse Length at 1ms (range is 300µs-10ms
with Range. Note that the length of the FM pulse does not affect resolution in the
same way as it does for CW mode. At very short ranges a long pulse length can limit
the ping rate due to the duty cycle protection mode.

6.2.7 Pulse Type

 CW (Continuous wave) is the traditional pulse type for multibeam survey.
 FM (Frequency modulation or X-Range) is selected for greater range performance,
FRDH operation, and instances where an increase in noise immunity may be required.
Depending on purchased features, only CW mode may be available. X-Range is an optional
add-on feature (see Table 1).
For instructions on how to adjust this setting, refer to the RESON Sonar UI User Manual (see
Appendix E Reference Documentation).

6.2.8 Vari-Swath

Vari-swath is a feature which allows the operator to select a swath width appropriate to the
application in addition to electronically steering the swath.
Vari-swath is available with all beam modes and can be used in conjunction with roll stabilization
and FlexMode 7
For instructions on how to adjust this setting, refer to the RESON Sonar UI User Manual (see
Appendix E Reference Documentation).
6 Max. 5ms at 66kHz for T50.
7 FlexMode is an optional add-on feature (see Table 1).
SeaBat T-Series Subsea Operator's Manual
Version 7
o Shorter pulses result in high resolution, but suffer in range performance.
o Longer pulses increase range performance at the expense of resolution.
o FM allows much longer pulses, and thus more energy, to be transmitted into the
water, resulting in greater range performance whilst maintaining full resolution.
o FM also provides better immunity to external noise and allows dual head sonars
to ping at the same time, a feature known as Full Rate Dual Head (FRDH).
. For details on the use of the various beam modes, see section 6.2.9 below.
NOTE
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6 ), and increase
January 31, 2019