82 User’s Manual Innomar SES Parametric Sub-bottom Profilers
82 Innomar Technologie GmbH (2020-09)
5.4 Sub-Bottom Multi-Ping Mode / Burst Mode (not for “smart”)
For the “light”, “standard” and “medium-100” models
there are a special “Multi-Ping Mode” and “Burst
Mode” available to ensure the highest possible ping
rate even in deep waters. This will produce either equi-
distant pings or bursts of sound pings.
Bursts are useful to reduce interference with other
acoustic equipment like multibeam (MBES).
Both modes are activated in the SESWIN “Home
Menu – General – System Mode”, see picture.
If “burst mode” shall be used the duty cycle has to be
set (active time of total time frame in percent) within
the SESWIN “System Setup – Settings – General –
Special Transmit Modes” menu (see section 4.11.6 on
page 55):
Both, “Multi-Ping Mode” and “Burst Mode”, are possi-
ble with internal trigger only. They will not work cor-
rectly if the system is triggered externally.
Principle of “Multi-Ping Mode” and “Burst Mode”:
Transmit pulses for “normal” echo sounding, ping rate depends on range end respective water depth (a), “Multi-Ping
Mode”, ping rate depends mainly on range length (b) and “Burst Mode” with omitted pings (c). In this example burst
mode duty cycle was set to 70% active time. Omitted pings are placed at the beginning of basic transmit cycle.
Ping rate can be estimated as follows. Between subsequent pings there is a dead time of approx.
10 ms. Supposing a sound velocity of 1500 m/s, the resulting ping rate PPS in “normal” ping
mode (internal trigger) is: PPS = 750 / (RangeStart + RangeLength + 7.5).
In “Multi-Ping Mode” additional pings are placed between the “normal” pings, if possible. For this
“Range Start” has to be at least 40 m and larger than 3 times “Range Length”.
To give an example, for “Range Length” set to 10 m and “Range Start” set to 70 m, we would get
a ping rate of 8.6 pps in “normal” mode, but 25 pps in “Multi-Ping Mode”.
If “Multi-Ping Mode” or “Burst Mode” is used, there may be artefacts visible in the echo prints that
are produced by water-column features (e.g., fish schools) or additional multiple echoes. To
check if features visible are real, you should switch off deep-sea pulse mode temporarily.
For both modes it is important to ensure the water depth is correct.
(a)
(b)
(c)
Basic Transmit Cycle (Range Based)
DSM Transmit Cycle
(Range Length Based)
Transmit Pulse Data Sampling Range
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