G-858BP Backpack Mag
Operators Manual
Advanced Features
The G-858BP has many features allowing a great amount of flexibility in defining your position and
viewing the survey site. This section describes the ability to define more arbitrary positions, and re-define
the survey grid.
Software States
Before discussing the advanced features, it will be helpful to define some states the G-858BP can be
in, in order to explain when certain operations will work.
There are 3 active states of the G-858BP in continuous mode:
Acquire State.
In this state, the system is storing data, generating the woowee tone, and updating the analog sweep
trace of the magnetometer output. Pressing the END LINE key sends the system to the Ready State.
Ready State.
This is the state the system is in between lines, for example. Data is not being recorded, the woowee
sound is off, and the sweep trace is frozen. Pressing the MARK key sends the system to the acquire state.
Pause State.
The system enters this state from the Acquire State when the pause key is pressed.
Positioning Data
In order to interpolate a position for each individual reading, the system must have a position defined
both before and after each segment of readings. Because of this, you cannot press ESC from the acquire
state. This would leave a series of readings without an ending position, so the most recent readings could
not be properly located.
There are two position recording keys on the G-858BP: MARK and END LINE. As seen above, these
keys, in addition to recording the current position, control the transitions between the Ready and Acquire
state. They can therefore be used to start and stop data acquisition.
Press the MARK key at fiducial positions when you want to start or continue
data storage. Press the END LINE key at a position when you want to stop
data storage. You don't have to be at the actual end of a line to press the END
LINE key.
The END LINE and MARK keys also control the automatic tracking of the position. As you have no
doubt seen, the positions are automatically updated after each position key press. The MARK key
increments (or decrements) the vertical position on the display. The END LINE key advances the
horizontal position 1 line spacing.
While using the END LINE and MARK keys to control data acquisition when
surveying arbitrarily positioned segments, you must manually update the
correct positions.
Manually Entering a Position
You may enter new positions from either the Ready or Pause state. One way to do this is to bring up
the map display (press MAP) and move the cursor with the arrow keys. This will allow you to move to any
fiducial point. Another way is to bring up the acquire menu (press MENU), and type a new coordinate into
the G-858BP. This allows you to enter positions which are not directly at a fiducial point.
Note:
Neither method will allow you to enter points which are not on one of
the lines of the survey. To fill in more data between lines, you must redefine
the grid. See the section Multi-Grid Surveys in this chapter.
If you are currently in the middle of a series of readings, i.e. you pressed the PAUSE key and haven’t
yet entered a position, you may only position yourself on the same line you are on.
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