Frequently Asked Questions (FAQ)

Resistance Meters
How far apart must two RM15 systems be if they are operated in the same field ?
What is the detection depth of a Twin array ?

Geoplot

How do I save higher quality graphics image than the Save Graphic Plot method offers ?

Resistance Meters

How far apart must two RM15 systems be if they are operated in the same field ?

If you have two RM15 meter systems operating in the same field (and at the same frequency), then with a 0.5m Twin, the mobile frames need to be at least 40m apart and the remotes even further apart to avoid interference. If you use longer beam lengths then you should increase the separations accordingly.

What is the detection depth of a Twin array ?

A general rule of thumb is that a Twin array can detect targets to a depth of 1 to 1.5 times the probe separation, depending on the size of the target. So for a 0.5m Twin array this is equal to 0.5m to 0.75m and for a 1.5m Twin array this is equal to 1.5m to 2.25m. If the surface is stony then the noise generated in the background response will reduce detection depth. Whilst use of a wider array enables greater detection depths, resolution of features is correspondingly reduced.

Geoplot

How do I save higher quality graphics image than the Save Graphic Plot method offers ?
With Geoplot version 3.00p onwards you can print to file. Using third party printer drivers allows you to save much higher quality graphics plots (eg bitmaps, jpgs, tiffs) than you would obtain using the normal Save Graphic Plot.

The printer driver we recommend is the open source program PDFCreator. This is normally used to create PDF files but it also allows you to create the following file formats: PDF, PNG, JPEG, BMP, PCX, TIFF, PS and EPS. PDFCreator is available at :

http://sector7g.wurzel6.de/pdfcreator/index_en.htm

Download the file and install it as a new printer. Before launching Geoplot, set PDFCreator as the default printer and then go to Start, Programs, PDFCreator to display the Print Monitor form. Click on the File menu, Printer Options, to display the PDF Options screen. Click on TIFF under Formats and set the Resolotion to 300 or 600 dpi. This resolution will then be saved and applied to all grpahics formats in future. Click on Save, the options screen will disappear, then close the print monitor form.

Now start Geoplot and display your graphic at a size that ensures it all displays on screen. For example a 400m x 400m composite will display at a size of 1/4. Select Page Setup from the File menu and ensure that Top and Left Margins are set to the minimum possible which is 1cm. Select Print from the File menu. This will display the Print Graphics form. Select Scaled Print Size and set the size according to what image size you require. For example setting size to 2000:1 would generate a 20cm square image from a 400m x 400m composite. However, Geoplot has minimum margins of 1cm so that size would be just too big for A4 paper and a size of say 2100:1 would be better which would generate a 19cm square plot. Alternatively you can choose larger paper size A3 at the next stage in the Advanced .... In the Paper/Quality tab. Deselect Print Plotting Parameters then click on OK.

This will display the printer as PDFCreator. Click on the Properties botton to set Layout and Paper Quality etc (You do NOT need to select Advanced... from the Paper/Quality tab since this just sets the PDF resolution, not the graphic resolution, unless you wish to change the paper size from A4 to A3 for example).

Click OK to print. If the chosen print size is too large an error message will tell you the plot is larger than the page width and you should select a smaller print size (larger ratio). If all is well, you will see the Printing in Progress message and a progress bar in the bottom left hand corner. Once the printing is finished the PDFCreator form will appear. Here you can change the Options again. Once you are happy with the settings click Save. A Save As form will appear and you will now have an opportunity of where to save the file and also the type of file that will be saved. By default a pdf file will be saved so change the lowest entry field to a tiff file and give the file a suitable name. Click OK and PDFCreator will then start to create that file - this may take a some time. If you have the View After Save option ticked on the PDFCreator form you may find Windows Picture and Fax Viewer or Microsoft Office Document Imaging will then display a copy of the image if installed on your system - close that view since you do not need it. The graphics file has now been created and you can now open it up in the graphics program of your choice - for example you can use Paint Shop Pro. Here you can select just the graphics image for your publishing requirements.