MagSurvey Software Operation
Assure that the setup procedures have been completed, and that the sensor display shows as the correct horizontal distance behind the boat/operator (see the SETUP help topic for a discussion of the importance of proper sensor positioning – this will have a direct bearing on the accuracy of survey results).
When the sensor is positioned properly and is returning good data, click on Zero Mag (or press the Page Up key or press the Alt-Z keys). This will zero the magnetometer graph and establish a reference gamma reading. It is not necessary to "Zero Mag" if using a metal detector -- instead, adjust the metal detector to the proper gain and offset.
With the boat in motion and with the sensor tracking directly behind, when a convenient starting point for the survey is crossed, click on Set Origin (or press the Page Down key, or press the Alt-O keys). This will display a notice indicating to the operator to click on a screen starting point. This will now be the current position of the boat’s GPS antenna. The objective is to select a screen position based on the anticipated search area to be covered. If the starting point is a detected anomaly, it may be convenient to select a starting point in the center region of the screen. East-west parallel tracks are recommended for the survey where practical.
The View 2D/3D Chart button can be used at any time to alternate between viewing the 2D or 3D chart. The 3D chart is used for graphic visualization of anomalies, whereas the 2D chart is used for accurate and dependable navigation.
CAUTION: MagSurvey is not to be used for primary boat navigation. The blank screen background does not mean that there is sufficient depth of water for navigation, or even that there is water at all. MagSurvey simply provides directional and earth-positional information – the boat operator must keep a constant watch for obstructions and depth of water. MagSurvey neither steers the boat nor operates the throttle, although both would be possible in a world without litigation excesses. Perception Systems, Inc. is not responsible for damage to the boat, sensor, property, or any living beings.
The boat’s GPS position is indicated by the four cyan corners on the plot window, while the sensor position is indicated by the four yellow corners. The arrow pointer may be moved around in the plot window, and its location is displayed -- along with data pertinent to the location. The pointer latitude and longitude values indicate the center of the map element beneath the pointer.
Once the magnetometer has been zeroed, the origin has been set, and good data is being received from the magnetometer, GPS, and differential correction source, the Start Logging and Stop Logging buttons are used to allow logging of anomalies and map element positions visited. It is important to Stop Logging whenever the sensor is not tracking directly behind the boat’s displayed track-over-ground (TOG). The Home and End keys will also start and stop logging, respectively. Any time the magnetometer’s sensor is within a map element, the largest peak positive and peak negative anomalies are compared to any previously-recorded positive and negative peaks, and the resultant stored values are the most positive and most negative values sensed within the map element.
For marine surveys, since the computed sensor position is determined from GPS track-over-ground information (TOG), care must be taken to assure that the boat always has a positive forward motion whenever logging is enabled. Maintaining speed-over-ground (SOG) of one knot or greater is recommended (faster if there are currents present).
For best results, it will be necessary to re-zero the magnetometer from time-to-time to cancel-out unwanted drift due to natural gradation of the earth’s magnetic field, diurnal changes, sunspot variations, and small errors due to direction and proximity to the boat.
MARKING LANDMARKS AND OTHER POINTS OF INTEREST
ERASING BAD DATA
NOTE: Retrieving a stored survey will wipe out any on-screen plot data – if there is any data on the screen that should be saved, select Save Current Plot Survey first.
Any previously-recorded survey can be quickly loaded by clicking File selecting Load Previous Plot Survey, and selecting one of the options below. These menu selections are located in the upper left corner of the screen (the appropriate Alt-key codes may be used to obtain the same results). Two operational modes are supported. MagSurvey must be set to the compatible scale for the file that you wish to load.
NEW PLOT SURVEY
NOTE: Selecting New Plot Survey will wipe out any current on-screen survey data – if there is any data on the screen that should be saved, select Save Current Plot Survey first.
A new plot survey can be begun at any time by clicking File and New Plot Survey in the upper left corner of the screen (the Alt-F and Alt-N keys may be used to obtain the same results). The screen will be cleared and a new origin must be set.
Perception Systems, Incorporated
8117A Northboro Ct, West Palm Beach, FL 33406 USA
Tel: 561-433-0033 Email: email@example.com