Get Better Accuracy with a Handheld GPS

Inexpensive, handheld GPS receivers such as those produced by Garmin and Magellan (under $300) are a great aid for anybody who enjoys outdoor activities, but there are many factors that affect their accuracy. Following these steps should allow you to get better accuracy with any handheld GPS receiver.

Steps

Improving Positioning

1. Consult the owner's manual on the type of antenna your GPS has. Since antenna positioning is very important for accuracy it is good to be sure about what type of antenna you have. There are commonly two types - patch and quadrifilar helix antennas. The first one is built into the device and the other one is external. Remember to always point your antenna (regardless the type) towards the sky.
2. Get away from obstructions. Since GPS depends on satellite data it’s best to make sure nothing obstructs the signal between them. When trying to get a lock on your position with your GPS receiver be sure to stay away from trees, buildings, and other natural or man-made obstructions that can reflect or block the signal, thus degrading accuracy. The goal is to both be in view of as many satellites at once as possible and to get a clear signal.
3. Orient your patch antenna properly. GPS antennas may have different designs that can give you better signal from their certain positioning. Chances are you have a patch antenna in your GPS receiver (you can confirm it using a manual).Holding your GPS flat with a patch antenna will give you the best signal.
4. Orient your quadrifilar helix antenna. Hold your GPS erect if you have quadrifilar helix antenna.
5. Hold your GPS receiver at shoulder height. Even if you are standing in an open spot your own body may block the signal, so elevating your device to a shoulder height will give you better accuracy.
6. Turn and face different directions. When you are in an open field and have your GPS positioned properly the only other thing you can do to improve accuracy is to turn and face different directions in order to increase the number of satellites in view. The more satellites 'see' your device the better and faster your GPS will provide position information.

Making Use Of Averaging

1. Turn on "position averaging". This is a feature that allows your GPS to take measurements about once a second and calculate an average position before saving it in the GPS receiver's memory. It is needed if you want to pinpoint a specific location. Three minutes of averaging should provide enough measurements to improve the accuracy of your position.
2. Adjust averaging setting to collect more points. If you are located in an obstructed area you may need more data to pinpoint your location more accurately. Thus if your GPS is collecting just two or three points (coordinates) you should set it to ten or twenty. The longer you stay still and the more data you gather, the better accuracy you may get.
3. Stand still during the averaging. Your accuracy can get worse if you move (especially fast) while collecting points. If you are under a tree canopy or in other obstructed area be patient and gather as much data as possible to get most accurate reading of your position.
4. Use manual waypoint averaging. Instead of using an averaging feature on your GPS you can record your waypoint (fixed position) coordinates over the course of several days and average them by adding up the last numbers of your recorded coordinates and dividing the total by the number of readings (times you recorded the coordinates).

Using Augmentation Systems

1. Make sure your GPS receiver is WAAS compatible. There are some region-specific augmentation systems that can make your GPS more accurate. For instance, Wide Area Augmented System or WAAS was designed for North America. It provides corrected GPS signal through its network of satellites and ground stations. You can find out available systems in your GPS Menu > Setup > System.
   • There is a European Geostationary Navigation Overlay Service or EGNOS for Europe
   • Multi-Functional Satellite Augmentation System (MSAS) for Asia
   • GPS-Aided GEO Augmented Navigation System or GAGAN for India
   • System for Differential Corrections and Monitoring SDCM is in development for Russia
2. Turn on WAAS or your region-specific augmentation system. You don't need any additional equipment. Just press Menu button (twice, if necessary), choose Setup > System and choose the augmentation system you want. You can use WAAS outside the US but the data will not be corrected thus it won't be as accurate.
3. Make sure a WAAS satellite is visible to your GPS. Since not all satellites are WAAS-enabled you may not always benefit from the system. Trees and other obstructions may also prevent you from getting a corrected signal, so be sure to stay in the open unobstructed areas away from trees, cliffs, and basins.
4. Make use of the GLONASS system in obstructed locations. GLONASS (Globalnaya Navigatsionnay Sputnikovaya Sistema) is a Russian Global Navigation Satellite System that can work alongside your GPS and provide more accurate data faster from its network of 24 additional satellites. Developed in the 70's for navigation and global positioning, GLONASS is now used in commercial GPS receivers (as WAAS system), smartphones and tablets. Just like WAAS you can turn it on in Menu > Setup > System.

Tips

• It’s always a good idea to get out in an open field to get the best signal but if you’re in a car and need to boost the signal an external antenna (between $20 and $35) might be an option, although not many GPS receivers support it.
• Some GPS receivers do not support “position averaging”. Other GPS receivers automatically perform "position averaging". But with most GPS receivers the user must activate this function.
• You can also take a few coordinate readings of your waypoint between moving from it up 40 feet away in various directions and then perform averaging.
• 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.
• Power saving modes may impede your positioning so disabling them will give you better accuracy but will result in shorter battery life.
• If you cannot change or adjust your location try to make the most of your positioning (by elevating your GPS, orienting antenna) and available systems (try each of them).

Warnings

• Read the owner's manual for your GPS before you venture into the wild to learn the type of antenna you have and any additional features of which you may make good use on a trip.
• All GPS receivers will usually have 95% accuracy, especially in favorable conditions (open unobstructed areas) but you can never rely on it as your sole means of navigation. The conditions for accuracy may not be very good and the battery life is limited. Always have a backup plan in the form of a good old map and a compass.
• A GPS receiver can be more distracting than a cell phone. Pay attention to what you are doing and where you are going, especially if you’re in a car.

Things You'll Need

• An inexpensive, handheld, GPS receiver

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