One of the first reasons you might suffer from GPS interruption, is the U.S. Government. They perform interruption tests on GPS systems quite often and there is really nothing you can do about it. You might experience interruption in the following places:
China Lake, CA Lax, CA Cedar Rapids, IA White Sands, NM Cape Canaveral, FL Patuxent River, MD Rancho Bernardo, CA Nellis AFB, NV
Another cause of interruption is shutdown of two Wide Angle Augmentation System satellites. This system is used as a no-cost differential correction signal for GPS. They are maintained by the FFA or Federal Aviation Administration, but are also available to civilians. The reason for this error is because some systems require the WAAS correction to operate properly. If you think you are experiencing this problem, you need to update your GPS system software. Most GPS manufacturers have information posted on their websites about firmware updates that fix problems just like this.
One of the most common reasons is objects blocking a GPS signal. An expert was quoted saying, “anything that can block sunlight can block GPS signals.” This could be anything from a building, tree, bridge, or even a vehicle. The only way to solve this problem is to move to an open location that can receive a signal.
Additionally, signals can be interrupted by disturbances in the atmosphere where they must travel, and the ionospheric layer is sensitive to solar disturbances which are currently at a solar maximum of an 11 year cycle. One could certainly expect frequent interruption for several years before a lull in the cycle.
By: Chaz Newman
Posts Tagged ‘Gps Signal’
Top Causes of GPS Interruption
February 8th, 2010How Accurate is GPS?
January 27th, 2010
The answer to this question keeps changing along with advancing technology as well as United States law. The first consumer GPS receivers on the market were far less accurate than the receivers available today even though the satellites are the same. Also, before the year 2000, the military intentionally introduced inaccuracies into the civilian GPS signal for “security” reasons. They called this intentional signal error “Selective Availability”. In May of 2000, President Clinton made a decision to turn off SA and allow civilians access to increasingly accurate GPS signals. The military still has the ability to turn off or introduce errors into GPS signals at any time and with no notice but this ability is generally only used for specific reasons of national security.
The best consumer GPS technology available as of 2007 achieves an accuracy level of 15 to 30 feet under normal conditions. Garmin, currently the most popular manufacturer of GPS receivers, claims their GPS units are accurate to within 50 feet 95% of the time. Even within the Garmin GPS receiver line, accuracy specs differ because of the different chips used in the design of different receivers.
GPS Receiver Design Affects GPS Accuracy
If you are looking for the most accurate consumer GPS unit, it’s important to pay attention to the unit’s chip type. The latest technology in GPS receiver chips is the SiRFStar III from SiRF. With this chip in your receiver and WAAS enabled you can expect to reach the best GPS accuracy levels available under current conditions.
Environmental Factors Affect GPS Accuracy
Many different environmental factors can also affect the accuracy of your GPS receiver. Heavy tree cover, tall buildings, deep canyons, and any location in which your view of the sky is limited can affect how accurate your GPS is. Atmospheric conditions can also degrade the accuracy of your GPS unit.
As you can see, there is no easy answer to the question “how accurate is GPS?”. However, you now know the main factors that can affect GPS accuracy.
By: Markus Hamilton
