How to Get Better Accuracy With a Handheld GPS

Inexpensive, handheld GPS receivers such as those produced by Garmin and Magellan are a great aid for anybody who enjoys outdoor activities. There are many factors that affect the accuracy of the positions reported by a GPS receiver. Following these steps should allow you to get better accuracy with an inexpensive, handheld GPS receiver.

Determine the type of internal antenna in your GPS. This information will likely be listed in a table of "specifications" in the back of your owner's manual. There are two main types:

• Patch antenna, and
• Quadrifilar helix antenna

Hold your GPS properly to receive a stronger signal from the GPS satellites:

• If you have a patch antenna hold your GPS flat
• If you have a quadrifilar helix antenna hold your GPS erect

Stand where you have a clear view of the sky. Buildings, hills, trees, etc., will block the signals from the GPS satellites. The goal is to receive the signal from as many GPS satellites as possible.

Hold your GPS at shoulder height. Even your body can block the signal from the GPS satellites.

Use "position averaging". This is a feature that allows your GPS to take many measurements and then calculate an average position before saving it in the GPS receiver's memory.

Turn on the WAAS capability. The WAAS signal is broadcast from several geo-stationary communications satellites. The WAAS signal provides corrections for your GPS measurements and enhances the accuracy of your GPS receiver.

Tips

• It is not necessary to constantly hold the GPS in the correct position at shoulder height. You only need to do this when you want to get better accuracy, e.g., when you are recording a waypoint.
• Some GPS receivers do not support position averaging. Some GPS receivers automatically perform "position averaging". But with most GPS receivers the user must activate the position averaging function. The GPS receiver will take a measurement about once a second. Three minutes of averaging should provide enough measurements to improve the accuracy of your position. It is important to stand still during the averaging.
• WAAS was developed to improve GPS accuracy for aviation in North America but it also works on the ground if:
  
  
  • your GPS receiver is WAAS capable
  • you are in an area covered by WAAS corrections
  • you can "see" a WAAS satellite from your current location.

Warnings

• Never rely on a GPS as your sole means of navigation. Always have a backup plan.
• Read the owner's manual for your GPS before you venture into the wild.
• A GPS receiver can be more distracting than a cell phone. Pay attention to what you are doing and where you are going.

Things You'll Need

• An inexpensive, handheld, GPS receiver