Science and Technology News

Friday, February 20, 2015

10 GPS myths: Busted

by Brian Hagberg
50th Space Wing Public Affairs


2/20/2015 - SCHRIEVER AIR FORCE BASE, Colo. -- GPS has been broadcasting signals for nearly 40 years. During that time, a number of myths, misconceptions, conspiracies and falsehoods that have been raised. Let's examine 10 common myths surrounding GPS. This list is presented in no particular order.

1. The U.S. military controls GPS Top GPS Facts

GPS is operated by the 2nd and 19th Space Operations Squadrons at Schriever Air Force Base, Colorado; however, the U.S. Government owns GPS and the program is paid for by U.S. taxpayers. According to GPS.gov, GPS receives "national-level attention and guidance from a joint civil/military body called the National Executive Committee for Space-Based Positioning, Navigation and Timing." The committee is co-chaired by the Deputy Secretaries of Defense and Transportation.

Top GPS Facts2. The U.S. military has turned off civilian GPS signals for operational or combat purposes

Since being declared fully operational in 1995, GPS has never been deactivated by the military for their exclusive use during combat operations. There are millions of civilian users and monitors of GPS around the world. If the U.S. military had turned off civilian GPS signals, even for only a few seconds, those monitors would have made sure everyone knew about it.
The bulk of this myth stems from what's known as Selective Availability, which allowed the military to intentionally degrade public GPS signals for national security reasons, most notably during Operations Desert Shield and Desert Storm. In May 2000, President Bill Clinton directed the government to discontinue use of SA and this policy has remained in place ever since. President George W. Bush took the policy a step further when, in September 2007, he announced that the government would procure GPS III satellites, which do not have the SA feature. Once these satellites achieve full operational status, SA will no longer be an option, thus eliminating this myth permanently.

3. Military GPS is more accurate than civilian GPS Top GPS Facts

The accuracy of GPS signals in space is the same for both military and civilian GPS, says GPS.gov. The main difference, for the time being, is that military GPS operates on two signals, while civilian GPS operates on one. However, civilian users will soon have two new signals to operate on. In June 2014, a group consisting of 2 and 19 SOPS, Space and Missile Systems Center, Headquarters Air Force Space Command, the Department of Defense and Department of Transportation completed an upgrade to current GPS satellites allowing them to broadcast the L2C and L5 civilian signals. The signals are not yet fully operational, but once they are, civilian users will have access to two signals as well.

Top GPS Facts4. The closer you get to a military base, the better your GPS signal will be

"So I'm sitting in a restaurant with my lovely wife and this guy at another table, the kind of guy (who) talks loud so everyone is aware he is an expert on whatever subject it is he's talking about, starts talking about GPS," said Lt. Col. Matthew Brandt, 2nd Space Operations Squadron commander. "My wife whispered to me, 'He's wrong, isn't he?' 'Oh yes,' I responded. 'He's way off.' After a while the guy boldly proclaims to the entire restaurant, 'Of course, you know GPS always gets better the closer you get to a military base!' and I promptly spit my drink across the table."

As for being close to a military base, well, let's just say that my TomTom has a hard time even finding Schriever, let alone getting a signal boost when I'm there.

5. GPS resides only on phones, in cars and on hand-held display unitsTop GPS Facts

GPS is, and does, so much more than sit on your phone and wait for you to ask directions to the nearest coffee shop. GPS technology affects our lives in more ways than we could possibly imagine, from banking systems and financial markets to communications networks and power grids to weather forecasting and environmental protection efforts, GPS is everywhere (and those are just a few of the civilian uses!). GPS touches so many lives on a daily basis that the International Astronautical Federation presented GPS with the IAF's 60th Anniversary award because "GPS is the space program that touches and aids more humans every minute of every day in every corner of the globe."


Top GPS Facts6. The government gave 2010 census data collectors GPS-enabled handheld computers as part of a secret plot to take away our liberties

Census data collectors have been mapping home locations for a while now, they just got an upgrade from paper and pencil to computers in 2010. "The exact geographic location of each housing unit is critical to ensure that when we publish census results for the entire country, broken down by various geographic areas ranging from states, counties and cities, to census blocks, we accurately represent the data for the area in question," says the Census Bureau's website.  The site goes on to say an incorrect allocation of information to the wrong geographic area would result in inaccurate data to two areas, which could affect the distribution of funds to state, tribal and local governments.

7. The government uses GPS satellites to track/spy on usTop GPS Facts

The issue with this is, of course, the fact that the GPS device in cell phones is a receiver, not a transmitter. Thus, your phone is not constantly transmitting your position...unless you continue to utilize the "Hey, here's where I am!" feature through various social media platforms.









GPS Facts8. GPS won't work if it's cloudy or there is bad weather

People tend to correlate GPS with what they know about satellite television service, which is notorious for losing signal during times of adverse weather conditions. The GPS version of "clear view of the sky," simply means the receivers need a signal path clear of obstructions such as mountains or dense canopy, according to gpsreview.net. This belief seems to have lost traction through the years as GPS technology became more widely available.


9. If you get lost, it's GPS's faultTop GPS Facts

Some people have taken this one to the extreme. A Nevada couple heading home from a trip to Oregon in 2009, followed their GPS down a service road, got stuck in the snow and was stranded for three days before being able to get a cell phone signal. The driver said he was simply following directions from his GPS. This prompted some members of the media to write stories blaming either aging GPS satellites or a weak signal for the device leading the couple down the wrong road. The Air Force felt compelled to set the record straight as the Air Force Space Command Twitter account, @AFSpace, sent out this message: "While we do not want to speculate on what caused the couple to get stuck in the snow; the cause was not due to GPS signal."

"The signals that are coming down are very strong and healthy, said an Air Force spokesperson at the time. "In the event one of our satellites fails, we can immediately have another one up to have the full coverage that we need."  Even though there are 30-plus GPS satellites on orbit, only 24 are active at any given time. This allows for immediate replacement of signal if an issue arises with one of the satellites. Users should also remember the satellites only provide the signals, it's up to users to keep devices updated with current maps and information.
Top GPS Facts10. GPS navigation systems will always pick "the best route"

Most navigation systems will allow users to choose between shortest route, quickest route, scenic route or whether to include toll roads. These are all convenience services, but none of them purport to offer the "best route." That's probably because the designers are busy having the same discussions that have been occurring in gas stations and at street corners for years, namely trying to determine exactly which is the "best way to get to..." One thing current navigation systems can't account for is "local knowledge" of an area. GPS doesn't know that school lets out early every other Thursday or that everyone takes Main Street to avoid rush hour traffic. These are things people need to consider when determining which route to choose.

A special thanks to 2 SOPS members, Lt. Col. Matthew Brandt, Capt. Achille Aloisi, Capt. Douglas Ruyle and Tech. Sgt. Abifarin Scott for contributing to this list.

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