The MetLSurvey Metal Detector Mapping System (Preliminary Version) 

MetLSurvey is a combination software and hardware product for mapping anomaly hits from commercially available metal detectors.  The resulting surveys can be saved as survey files.  They can also be recalled for analysis (in review mode), or to add extensions to a previous survey (in append mode).

MetLSurvey (Metal Locator Survey) operates on the Garmin iQue 3600 GPS/PDA.  This specialized PDA uses the Palm operating system and has a quality, half-VGA screen (480H by 320W).  (Note: GPS is short for Global Positioning System, and PDA is short for Personal Digital Assistant.)  The Garmin iQue 3600 is no longer in production, but there is currently an ample supply of Garmin factory reconditioned units available on eBay and from other sources.  The approximate $200 USD cost of the iQue 3600 often includes an automobile adapter and extensive road maps.

The MetLSurvey system uses a custom, smart converter built into a cradle mount for the iQue 3600.  The converter circuitry translates the audio output of several basic types of metal detectors into digital data that the GPS/PDA can use.  The metal detector must have a headphone-output jack that provides one of several types of tone patterns.  The four basic types of tones that can be interpreted are 1) varying pitch due to size or proximity of the target, 2) varying pitch steps due to the type of metal detected, 3) pitch steps, as above, but with a bell sound for the highest conductivity metals, and 4) varying amplitude due to the size or proximity of the target. A calibration function allows these frequencies, along with the appropriate conversion factors, to be remembered by the converter-cradle’s microcontroller “brain”.  The last stored set of calibration values for each of the four basic metal detector types is available for quick recall. 

The area of a survey screen is 0.031 minutes of latitude by 0.031 minutes of longitude, or about 188 feet by 188 feet at the equator.  Positions of detected anomalies are stored by “map element”, and the width of a single map element is about 6 feet by 6 feet at the equator (0.001 minutes, lat or lon).  The further from the equator, the narrower (east-west) each map element becomes, although the north-south dimension remains fixed.  Detected anomalies are displayed as dots (the more significant the anomaly, the larger the dot).  The screen also indicates where detecting was done with logging enabled (this is shown as a tan background).

CAUTIONARY NOTE ON POSITIONAL ACCURACY:  Please note that this preliminary mapping system pushes the limits of the available accuracy of the GPS satellite system -- positional errors may be encountered.  Surveys need to be conducted outdoors with a good view of the surrounding sky, and with a minimum of surrounding structures or dense, tall vegetation.  When performing surveys, the operator should strive to maintain a clear shot from the GPS antenna to the appropriate high-above-equator, WAAS differential correction satellite.  In the US, the direction to the main geo-stationary satellite (#51) ranges from southwest (on the east coast), to south-southeast (on the west coast).  MetLSurvey will not plot anomalies unless a strong position is obtained, and the initial acquisition can take several minutes. 

            Detector Mounting Shown                                                Upper-Arm Mounting Shown

ACQUIRING THE PRELIMINARY MetLSurvey SYSTEM 

The complete system consists of two groups of elements:

1.  Limited quantities of the experimental version of the MetLSurvey system are available at $595 USD, plus $12 shipping/handling (USA).  Please include 6.5% sales tax for shipments within Florida, only.  This price includes the following components (Important:  see the cautionary note, above):

·   The MetLSurvey.prc operating program for the iQue 3600.

·   The MetLSurvey smart converter-cradle unit. 

2.  The following items are not included, and must be provided by the customer:

·    A Garmin iQue 3600 GPS/PDA

·    A compatible metal detector having a headphone jack that outputs one of the four general classes of audio output signals described above.

·    The customer must associate and use a personal computer for certain setup and data transfer processes (all PDA processes are normal Palm operating system functions and are fully described in the iQue 3600 documentation). 

                                 Converter-Cradle and Mounting Strap                                                 Optional External Battery Pack for Extended Surveys

SOFTWARE INSTALLATION AND SETUP

It is best to completely set up and get familiar with your iQue PDA beforehand.  Note that MetLSurvey does not require an SD memory card for operation): 

1. Install  the MetLSurvey software into iQue main memory (not SD card):
   1. Note the MetLSurvey.prc file’s location on the included disk or CD-ROM.
   2. On the PC, start the “Palm Desktop Software” included with the iQue 3600.
   3. Click on “Install”, then click add “Add”, and select the “MetLSurvey.prc” file.
   4. Select the attached iQue by its user name.
   5. Click “Open”.
   6. Click “Done”, and then do a HotSync on the iQue.

    

2. Set WASS mode for high accuracy GPS differential-correction mode:
   1. Click the “Prefs” icon on the main menu.
   2. Click the small down-arrow on the top right of the preferences screen.
   3. Click “Que”
   4. Click the checkbox next to “WAAS Enabled” (Note: you cannot select battery saver mode with WAAS enabled).

    

3. (Optional) To Set an iQue Shortcut Key to Run MetLSurvey:
   1. Click the “Prefs” icon on the main menu.
   2. Click the small down-arrow on the top right of the preferences screen.
   3. Click “Buttons”.
   4. Click the small down-arrow next to the image of the button that you want to use for the shortcut (the second-from-right, front button is recommended).
   5. Click on “MetLSurvey”.

HARDWARE INSTALLATION AND CALIBRATION

1. Mount the MetLSurvey converter-cradle:

a.  The cradle assembly can be strapped to the top of the paired metal detector’s housing, or it can be strapped around the operator’s upper arm (left arm preferred).  The mount has provisions for rotation and angular adjustments.

b.  After attaching the mount, insert the iQue 3600.  Assure that both of the latching pins are properly inserted.

c.  Plug the unit’s ¼” phone plug into the metal detector’s headphone jack.  If headphones are to be used, plug these into the 1/8” jack on the back of the converter-cradle.  If the audio level is adjustable, it must be set to the level it will be used during the survey.

d.  Extend the GPS antenna to a position that it will remain horizontal during the survey, with a clear view of the sky. 

2. Calibrate to the Metal Detector (this is normally only necessary the first time an associated metal detector is used with MetLSurvey – the calibration information will be stored in the converter-cradle):

a.  On the MetLSurvey initialization screen, click “Initial Metal Detector Calibration”.

b.  Another screen will appear.  Click on the type of audio output that your metal detector provides.  The calibration screen for that type of detector audio will appear, and will display additional information.

c.  With the metal detector over the least significant anomaly that you want to record (the lowest audio pitch or the lowest-conductivity metal), click the on-screen button to calibrate the low level.  In the case of motion detectors, you will need to time your tone generation with the press of the button – you will get a message indicating whether or not the tone was “caught”.

d.  With the metal detector over the most significant anomaly that just provides full scale deflection (the highest audio pitch, the highest-conductivity metal, or the highest audio amplitude), where necessary, time the beep and click the on-screen button to calibrate the high level.  The calibration parameters will be stored, and this will become the associated metal detector for that particular type of audio output.

e.  Check for proper calibration by detecting your metal test objects and observing the bar patterns at the top of the survey screen.  Especially in the case of motion detectors, if the bars are not correct then you will need to repeat the calibration procedure.

f.   Any time a different metal detector having that particular type of audio is used with this converter-cradle, you must repeat the calibration procedure, above, to associate that exact metal detector.  You can, however, select any of the other three types of detector audio, previously calibrated and stored, by clicking on the appropriate buttons on the first calibration screen.  Only one metal detector can be used for recording on any given survey.

OPERATION

1. Remove any SD card to conserve power and extend survey time.
2. Extend the GPS antenna to a horizontal position.
3. Press the shortcut key, or click on the “MetLSurv” icon to start MetLSurvey.
4. On the initialization screen, you can uncheck the box requiring highest available GPS accuracy, if desired.
5. On the initialization screen, either select “New Survey”, or click on an existing survey file and then select “Load for Append”, or “Load for Review”.  (Note:  in order to log new data using either “New Survey” or “Load for Append”, assure that the iQue is mounted in the converter-cradle when first starting the MetLSurvey program.)
6. For a “New Survey” only:
   1. Click “Set Origin” on the main screen.
   2. Wait for the GPS to indicate having acquired an adequately strong position.
   3. Click a point on the survey area of the screen that will represent the present location.
7. As long as you are located within the coordinates of the survey screen, your location will be indicated by a white box.  If you wander out of range, you can use MetLSurvey’s auxiliary functions to easily return to any point (see the checkbox functions, below).
8. For a New or Append survey (after positioning and adjusting your metal detector) click “Log Data” to begin the logging of tracks and anomalies.  “Stop Log” and “Log Data” can be selected any number of times during the survey to suspend and resume the logging of data.
9. The top of the main screen continuously displays metal detector and GPS status information.
10. When you want to save a survey, press “Save Plot”, and the survey on the screen will be saved to a Memo file identified by the current date and time of day.  (Note: appended surveys are also saved with the new date and time, leaving the original file intact).
11. If a red-bottom battery image or a low battery warning appears:  save the survey, end MetLSurvey using the escape key, and press the power button to turn the unit off.
12. In most modes,  the operator can use the checkbox functions on the left of the screen to provide useful, continuous, navigational information:

a.  Position checkbox:  Selecting this checkbox displays current latitude and longitude.

b.  Point checkbox:  Selecting this checkbox displays the latitude and longitude of the last point that the stylus touched within the screen survey area.

c.  Distance checkbox:  Selecting this checkbox displays the approximate distance and direction from your current location to the last point that the stylus touched within the screen survey area.  You can use this feature to conveniently point-to and return-to any point of interest.

12. After the survey to view, edit, or delete a stored survey file:

a.  Click the iQue “Memo Pad” icon.

b.  Click the file to be viewed, modified, or deleted.

c.  TO EDIT THE FILE:  MetLSurvey files can be modified as long as the file length and formatting is unchanged.  The lines and columns mimic the map layout of the survey (no matter the hemisphere:  north is always up, and east is always to the right of the screen).

d.  TO DELETE THE FILE: Any file can be deleted by clicking “Details”, then “Delete”, and then “OK”.  It is good practice to delete any superfluous memo files on the device. 

GENERAL NOTES ON USING THE iQue 3600

Please contact PSI directly for further information on obtaining a preliminary MetLSurvey unit.