Behind the Scenes

Bob Rennard, co-founder and chief technical officer, TeleNav

Because the condition and accuracy of the Global Positioning System (GPS) is core to our business here at TeleNav, we wanted to take a few moments to provide our thoughts on the recent articles you may have read from sources such as The Wall Street Journal and The Guardian regarding the deteriorating condition of the GPS based on a report from the Government Accountability Office (GAO). As with any situation involving predictions and unknown factors, there can be a variety of speculation and reports of worst case scenarios. Based on our review of the available information and my personal experience working as a principal engineer for the US Air Force in the design of the GPS, here’s our take on the situation:

Despite what some news outlets have reported, it’s unlikely that one morning the world will wake up to find that products depending on GPS are suddenly not receiving a signal and providing location and timing services. Over the course of its lifetime, the current GPS has been tweaked to deliver performance that has exceeded accuracy standards set out by the government when the current constellation was deployed. Even with degradation that may be seen with loss of aging satellites from the current constellation, the GPS will likely meet established standards for performance.

The system was designed such that the satellites are constantly crossing the sky and if one fails, the degradation due to that failure will correct itself within hours. This is because the current constellation of 24 satellites is deployed in six orbit planes and each satellite circles the Earth twice daily. This produces an “over determined” positioning solution; meaning that more satellites than are needed to deliver accurate positioning are usually visible, so a single satellite outage will create limited problems.

Although we feel the threat of a “GPS Blackout” is highly unlikely due to the examples explained above and other factors, it would be irresponsible of us not to bring up the valid concerns that currently exist regarding the general state of the Global Positioning System. For reasons that largely remain unknown, the launch of new satellites (called Block IIF) to replace the aging constellation currently in orbit (made up of satellites from Block IIA, IIR and IIR-M) has been delayed and the current constellation continues to age past the life cycle originally intended for these satellites. In an effort to shore up the constellation while facing the delay in the Block IIF launch, a decision was made to launch Block IIR-M satellites. The latest of these satellites was launched in March, but has not been able to function properly within the current constellation. The last IIR-M satellite will not be launched until the issues with the first are resolved.

As a step in the right direction, the first of the long-delayed Block IIF satellites is scheduled to be launched in November 2009, which will certainly be a key point in ensuring the constellation doesn’t experience degradation and performance issues. However, it’s still unknown how quickly all Block IIF satellites will be launched. It’s possible the performance of the current constellation will be impacted by any additional launch delays of Block IIF. Until all of these issues are resolved, we’ll be dependent on the current GPS constellation, which as mentioned, is performing well at this time.

Another point that the GAO report emphasizes is that the Block III satellites will not be available in 2010. They are forecast to be delivered starting in 2014. The GAO is pessimistic that Lockheed Martin will be able to design, fabricate, test, and launch the satellites in just six years given the delays in the Block IIF program. However, Lockheed Martin has been building the Block IIR and IIR-M satellites for the past 15 years, so their experience in making GPS satellites is considerable.

As you can see, there are factors, many of which still remain unknown, that may impact the performance of the GPS constellation. We understand that worst case scenarios must be taken into consideration and that it’s possible these situations may impact the performance of GPS. However, as mentioned earlier, we feel it’s highly unlikely a “blackout” would occur and based on my knowledge of GPS, I’m confident saying that those of you who use TeleNav products or other GPS devices will not be significantly impacted by the current situation.

I’d also note that as much as we hate to admit it, GPS is often relied on for things other than keeping TeleNav users on track. The government relies on the system for a number of programs and it’s in its best interest to keep the system performing at its best. One such program is the e911 program implemented by the FCC which in its Phase II stage (2001), required that carriers offer location detection capabilities on all handsets operating within the United States. Many carriers depend on embedded GPS for this location detection functionality.

In addition to ensuring the success of its own programs, the government stands to benefit from the success of companies such as TeleNav that rely on the GPS. The government receives billions of dollars in tax revenue from companies with core businesses that are dependent on the health of the GPS. Take into consideration companies such as Garmin, Qualcomm, Trimble, Broadcom, NAVTEQ, TomTom and of course TeleNav that rely on the GPS to provide location information for many of their product offerings. If the GPS stopped performing at acceptable levels, the profitability of these companies would be greatly impacted, thus impacting the government’s tax revenue potential. GPS and location-based services is certainly a rapidly growing market and you can be certain that Uncle Sam wants to ensure it keeps an ever growing industry segment operating and generating revenue.

With all of that said, I’ll point out again that this is simply our take on the current situation. There are many explanations available and we invite those of you who are curious to explore these to form your own conclusions regarding them.