Doc. P/N:
WSP-009-008
Version: V1.3
Issue Date:
April 2014
62
9.9
Why is there a ring displayed just above the seafloor? What causes
these ‘ring’ marks? How can I get rid of them?
This ring is a by-product of the multi-beam technology of your WASSP system. It is supposed to be there
but in practice we want to make it as difficult to see as possible. To avoid these rings confusing the seafloor
tracking algorithms or being confused as fish marks, the
Minimisation
feature allows these rings to be sup-
pressed on the Sonar display. Care should be taken because hiding these rings will also make it hard to see
any signals below them such as fish on the bottom.
When a signal arrives at the receiver it creates a shadow like effect that creates a ring of much weaker
echoes - the stronger the signal, the stronger the rings. Unfortunately the signal return from the seafloor is
many orders of magnitude stronger than a fish echo and thus the shadow of weaker echoes can be compa-
rable to fish targets.
How do I know if I have a problem
then?
When running with Auto Power
By Signal (BLUE) and the power level is
above 1 then the required minimisation
should be
1500 or less
. The lower this
is the more chance of seeing fish below
the ring but the more chance of the
rings being visible on the Sonar display.
If you are required to use a higher power
level then it may well be impossible to
hide them completely with Minimisation.
If you have the system working with no
sign of these rings and then they start to
appear and you have not changed the
Minimisation settings then something
has changed for the worse – keep reading.
►
Too much power
This is the most common cause of problems. When there is too much acoustic energy in signals returned
from the seafloor they may distort. Distortion of the signals will cause ambiguity in resolving the position
and thus create rings of very high amplitude. Unless in very shallow water,
Auto power by Signal
mode will
automatically try to select the highest power level that doesn’t cause distortion. You may get the occasional
strong return causing faint rings, but this is good so that you have as much power as practical for detecting
fish.
►
Gain settings
This ring will appear more or less significant as the
Gain Control dial
is changed (see “Gain Control” on page
Normalise
option will change the relative intensity.
►
Shading of Receiver
Any difference across the receiver caused by marine growth or any other irregularity across the face of the
receiver will contribute to a reduction in the discrimination of the WASSP system. This will lead to higher
intensity rings.
►
Reconnection Fault
If the cable from the BTxR to the Transducer was disconnected and has been reconnected recently it is
possible the receiver is connected incorrectly. Check the colour codes of Ethernet connections.
►
Calibration
It is possible that the system calibration was disrupted by another sounder. Close the WASSP GUI and re-run
to allow the system to re-calibrate.
►
Electronics Failure
If one or more central channels fail in the electronics this will increase the intensity of the ring.
►
Configuration
Changes made in the Technician configuration could significantly change the system performance. Restart
the WASSP GUI if you are unsure what state the system is in. The
Configuration Manager
has a
Defaults
op-
tion to load your default configuration settings if all else fails (see “Configuration Manager” on page 45).
