User's Manual

Smart Systems User’s Manual Version 1.1
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If a GPS receiver is attached to the DVL, a file containing GPS information can be
saved. In Fuducial Tagging mode, whenever a fiducial marker is added to the data, a
line of GPS information will be added to the GPS file (see Section 6.3.5)
6.2.5 Section C - Menu
The bottom section (Section C) contains the user menu selection and current program
settings. This includes:
1) The total depth (and time window) to the bottom of the data image in
Section B (see Section 6.3.1),
2) The Gain button and current Gain setting (see Section 6.2.6),
3) GPS information (if GPS receiver attached, see below and Section 6.3.5),
4) The current odometer position,
5) The Repeat Trace Number which indicates when the system is being
moved too fast (see Section 6.2.7) and
6) The Calib button for calibrating the velocity setting (see Section 6.2.8).
If a GPS receiver is attached to the DVL (see Section 6.3.5) a message will appear in
the bottom left corner of the menu indicating whether the GPS data is successfully being
logged. The possible messages are:
1) GPS: DGPS fix means differential GPS data are currently being logged.
2) GPS: GPS fix means standard GPS data are currently being logged.
3) GPS: fix not valid means GPS data are NOT currently being logged.
This is usually because GPS satellites are not available.
4) GPS: No Input means the GPS receiver is not operating properly. Check
the settings and test the system (see Section 6.3.5).
5) GPS: No GGA means the GPS receiver is not outputting a GGA NMEA
string that the DVL requires (see Section 6.3.5).
6.2.6 Gain
During data acquisition, the Gain setting can be changed by pressing the Gain button
until the desired setting appears. This can be done while the instrument is collecting
data; there is no need to stop first.
The signals that the Noggin system collects from the ground can be very weak,
especially from deeper objects. To see these weak signals it is necessary to amplify or
apply “gain” to them.
The Gain setting controls how much the signal is amplified. It varies from 1 to 9 with 1
the lowest and 9 the highest. In general, if the target is relatively shallow (1-2 metres) a
low gain value can be used. If the target is deeper or if the screen seems to be blank or
speckled in the lower part of the data section, increase the gain setting. Remember,
however, that if the Noggin signal is not penetrating to the maximum depth setting, even
the maximum gain setting will not show any data.
Figure 6-2 shows the effect of the gain setting. The data on the left has a gain of 1
incrementing to the right up to a gain of 9.