Differential Global Positioning System (DGPS)

GPS / DGPS Made Easy

How to plot a position

Let's say your GPS or DGPS receiver shows your position as being 47° 18 minutes 04 seconds North and 53° 58 minutes 02 seconds West.

Using your parallel rules (a ruler, compass or pair of dividers can do the trick, if you do not have a set of parallel rules), locate the coordinates on the latitude scale. Again, be careful to ensure accuracy using these tools. Locate the coordinates on the latitude scale. Estimate the distance and with a sharp pencil mark the location.

Next, take your parallel rules and place one edge on a nearby latitude line. Slide the other edge until you hit your mark and draw a line to it.

Repeat the same process for your longitude by using the longitude scale.

The intersection of these lines is your location on the chart.

In other words X marks the spot...

So remember...

• Use recent chart editions;

• Keep your charts up-to-date using the Notice to Mariners publication; and

• Use the largest scale chart available which is more accurate since it covers a smaller area.

For more information on purchasing charts and about other matters (chart catalogue, charts, symbols and abbreviations), please contact your nearest Chart Dealer or CHS office, or visit the CHS web site at www.chs-shc.gc.ca/

• What is GPS?

• How does it work?

• What is DGPS?

• GPS/DGPS & Nautical Charts

• How to plot a position

• Practical Application

• Definitions

• DGPS Stations in Canada

• Acknowledgements

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