AIS, ARPA, RADAR, Remote WAN Connections
on the Target form to change AIS display settings
Notes on the screen shots
The RED targets are those that pose a collision
threat as per the settings in SOB that you enter to define what poses a
danger (see image of the SOB Settings options to the right).
The YELLOW targets are still "alive"
according to the Time to Inactive setting.
The GREY targets indicate that a message has not been
received from the target for the time set by Time to Inactive. If
"Auto purge if Inactive" is checked, or the [Purge Now] button
pressed, then all the GREY targets will be removed.
Terms and Acronyms
||Closest Point of Approach
The position of your ship (latitude and longitude) at the point
when your ship and the target ship are at the minimum distance apart.
This location can, at times, be misleading ... for instance it can be
half way around the World, or at a point after your two paths cross.
SOB considers the ships as "passed" if the CPA is behind
your current position.
||Time to CPA
Is the time remaining until your ship reaches the CPA
||Distance apart at CPA
This is the actual closest distance that the ships will ever be. In
the Quick Info box below, it is "Clearance Distance" at the
||Distance To Go to CPA
The distance you are from the CPA position. This is a calculation
based on the TCPA and your current speed.
||(or MARPA) Automatic Radar
A pre-AIS technology based on
RADAR signals to determine lat/lng, speed and course of defined RADAR
blips. MARPA (Mini ARPA), for all intents and purposes, is the same as
ARPA, just without the official ratification.
|Detailed information is available for each target
Quick Info [Enter]
Click the [Info] button (or press the [Enter]
key) and hover the pointer over a target to get some Quick Information
This selected target becomes the
Active Target for tracking. See next ...
Note, the "hotspot" for each target is the
tip, not the centre.
is from the NMEA sample AIS logfile installed with SOB: the ship SEAFRANCE
selected in the list of acquired targets (below), and is being dynamically
tracked with current data displayed in the ViewPanel (below, at left).
|| Tracking Targets
Info mode active, the last target that the info cursor
hovers over will display detail in the Targets Panel
enabled (on the Targets List, the [Mark CPA] button), the
Hazard waypoint symbol will be displayed at the CPA. This is a
temporary waypoint and will not appear in SOB's waypoint list. Its
position is updated whenever the CPA with the chosen target changes
location, it is therefore possible that a new position for the CPA
waypoint will overlap previous positions, however with the next chart
refresh, only a single CPA waypoint will be drawn at the current
example scenario (right, click for full size image), shows a collision
threat with the red target in the lower-right of the image (MMSI
232001710), which is marked as a Tracked Target, with received data
and CPA calculations in the white Targets Panel. A wpt shows the CPA
with this target.
| Looking at the right-hand panel of
the Acquired Targets list
tells us that it is a 135 metre long Passenger ship bound for Calais. However
if you run the logfile, you can watch this ship LEAVING Calais, so I would
suggest that the Ship's officer has not updated the "destination"
yet. There are often errors noticeable in the "Ship's
Static Data" that must be entered by the operator in their AIS
transponder. The dynamic data however, (lat/lng, sog, cog) is never in error
as it originates from the GPS or other instruments, and is not subject
to human mistakes!
The list can be sorted on any column
by clicking the column's header box (eg: the MMSI, Name, Rng, Crash,
TCPA etc grey labels). Click the header box again to reverse the sort
ClearAll, Delete and Hide Targets
buttons require no explanation.
[Pan to Target] will centre
the display at the target's position. The cross-hairs that always mark
the centre of the SOB screen (unless in de-clutter mode) will make it easy to identify the Target
[Pan to CPA] is only enabled
if the target poses a collision threat. Then it will centre the screen
at the CPA. [Mark CPA] will place a regular SOB waypoint at
this position (which, of course, can change its location never,
frequently or continuously).
Message] requires a transponder and is not yet implemented.
Friend's List [F]
|This is a free-form list
that the SOB user can create to highlight or exclude any particular
target for any desired reason.
Acquired Targets that are found in
the Friend's List will be drawn on the chart display using the colour
chosen for the Friend, and will include the Nick Name chosen when
displaying the Target label on the chart surface.
Any entry in the list can be excluded
from the target display by ticking the Hide box. By default,
the ship with MMSI number of zero is set for exclusion (it is common
for AIS and SOB to "pick up" a zero MMSI when first starting
to acquire targets, and usually only indicates an incomplete AIS message was
received). Excluded targets will still display in the Target List, and
can be redisplayed with the [Show Target] button if hidden.
Note: the Target Friend's feature
does not work without some extra information for WAN and ARPA Targets,
as their unique numbers (which SOB uses to simulate an MMSI number) is
unknown before reception. Once a new WAN or ARPA target is acquired,
the new unique MMSI number for it can be used when adding it to the
Friend's List and then named and coloured as you wish. Press the [Add
to Friends List] button to simplify these steps.
The list of friends is maintained in
a simple text file in the SOB main folder: FRIENDS_List.txt.
This file can be manually edited, or created from a spreadsheet list
etc. Be sure to include the data delimiters "~" after each
field, and at the end of each line.
|If you are equipped with an AIS transmitter/transponder, then
SOB makes it easy for you to "set" your AIS details in compatible
devices (your AIS transponder must be capable of receiving static ship's data
via the SSD and/or VSD NMEA sentences)
ARPA / MARPA Targets
SOB reads the TTM, TLB and TTL NMEA sentences,
sent from compatible RADAR units, and displays the targets in the same way as
the AIS targets. However ARPA targets don't transmit the same amount of detail
about themselves (so no Ship Type, Destination, dimensions ... ie: none of the
Static Data at all).
SOB creates a unique MMSI number to associate to
each received ARPA target. A user-defined name for any targets will also be used
by SOB (the target's name is typically keyed in at your RADAR device's console).
Not all RADAR units are ARPA (or MARPA) capable. Check your RADAR's
specifications if you are unsure.
|VRM / EBL Targets
The RSD NMEA sentence contains information about the
RADAR cursor's current location, and up to two separate RADAR targets (usually
referred to as VRM/EBL marks), as set by
the user of the RADAR device.
The targets displayed
in SOB are simulated targets that SOB creates from the VRM/EBL marks set by the
user of the
RADAR device. SOB will draw these simulated targets on the screen as a circle
(rather than the triangle used for AIS and ARPA targets).
SOB can also re-display the RADAR unit's cursors, marks and
range-rings directly on the chart surface.
NOTE: SOB can not display the Raster Image that the
RADAR builds from the returned echoes of its magnetron.
"SOB NMEA DATA.log"
The NMEA DATA log file is
used to replay a voyage in SOB. In fact ANY plain text file containing
NMEA data can be used by SOB to replay a voyage (ie: data captured by HyperTerminal).
These files can be easily copied (or emailed) between different
computers and the past voyage replayed as often as you wish.
The data written to the
file will resemble the text in this example, each line as known as a NMEA
Optionally save ALL NMEA data received by SOB to a
standard NMEA format log file by "ticking" the checkbox on the
Data form which selects whether to write this log file or not.
Regularly throughout a long
voyage, or at the completion of your voyage, use Windows™ File Explorer to save this data to an
appropriately named file and place it in the \LogFiles folder for easy
replay from the buttons on the Raw NMEA Data form.
The folder that this file
is found in is the SOBvMAX\Logfiles folder.
NOTE: This logfile is ONLY AVAILABLE after SOB exits. If you
try any file operation on it while SOB is running you get a "File
Open Error" from Windows.
See also Easy
When SOB exits, the current
on-screen PastTrack will be logged to two different files:
||will be appended with
any unlogged points from the current session.
This file is controlled by the settings on the PastTrack
The data in this file is designed to be thoroughly analysed with Excel. (see Power
Users - Analyse your Voyage)
will be created to temporarily
hold the current PastTrack, this track will be redisplayed in SOB
when next started.
The LastTrack file uses the same
format as the PastTrack file. This allows ANY logged track
to be redisplayed in SOB.
Analysing your Voyage
SOB will automatically create a Log File: LogFiles\!PastTrack.txt
However, if SOB has not been Unlocked,
then PastTracks will not be logged to file (ie: if AccessLevel
= 0, or trial period has expired).
SOB logs a lot of data about the ship every few seconds to a standard
"row/column" formatted text file for direct
importing into a spreadsheet for archival purposes or voyage analysis.
The logfile is appended every few hours (about 4.5) of
running time, and any unlogged data is added to the logfile when SOB
This file can get quite large when SOB is employed in a
real-time navigation scenario. The file grows at about the rate of 1
Megabyte every 24 hours of running time.
A typical use would be to
import the logfile into a spreadsheet every day or so, deleting the !PastTrack.txt
file after importing. The logfile will be re-created the next time
(about every 4.5 hours) that SOB is logging data.
The data logged by SOB to
this file is:
time for this row of data
Dead Reckoning or Voyage Replay
(Height above MSL)
When imported into Excel,
the resulting data will appear as: (after some simple formatting)
Now use Excel's powerful
tools to analyse or present this data in a multitude of different ways.
For example, a graph of the apparent wind speed for the voyage can
reveal much interesting and useful information:
|Zoomed-in from the
example chart (pictured above), the entire voyage, or any part
of the voyage can be visually analysed with Excel's powerful
To create this chart in Excel,
simply highlight the Time column and the AWS
column (for this example), then press the
Chart Wizard button on the Excel toolbar, select a
"Line Graph" option from the choices provided and