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Schriever Sentinel

GPS squadrons add pair of new civil signals

U.S. Air Force photo Maj. Shanna Corbet, 19th Space Operations Squadron, reviews procedures with Airman 1st Class Alan Faeldan, 2nd Space Operations Squadron, during the Civil Navigation implementation April 28, 2014, at Schriever Air Force Base, Colo. The initiative will allow Air Force Space Command to broadcast Civil Navigation messages on all operational GPS satellites capable of transmitting L2C and L5 signals.

U.S. Air Force photo
Maj. Shanna Corbet, 19th Space Operations Squadron, reviews procedures with Airman 1st Class Alan Faeldan, 2nd Space Operations Squadron, during the Civil Navigation implementation April 28, 2014, at Schriever Air Force Base, Colo. The initiative will allow Air Force Space Command to broadcast Civil Navigation messages on all operational GPS satellites capable of transmitting L2C and L5 signals.

By Scott Prater

Schriever Sentinel

The world’s civilian GPS users garnered two brand new navigational signals recently, thanks to the concerted efforts of the 2 SOPS and 19 SOPS and a broad team that included members of the Space and Missile Systems Center, headquarters Air Force Space Command, the Department of Defense and the Department of Transportation.

When payload operators here flipped the “on” switch, capable GPS satellites began broadcasting the new signals, known as L2C and L5.

“Our payload operators, navigation analysts and engineers, in conjunction with the Space and Missile Systems Center GPS Program Office and the higher headquarters team, have implemented this new civilian navigation capability more than three years ahead of schedule,” said Lt. Col. Thomas Ste. Marie, 2 SOPS commander. “Both 2 SOPS and 19 SOPS are proud to have played a part in this acceleration. It is quite honestly, one of the most significant improvements to the Global Positioning System signal in decades.”

The L2C and L5 signals represent the first of several new civil capabilities being added to GPS as part of the GPS modernization program announced in 1999. The L2C signal is designed to meet commercial needs while L5 meets safety-of-life transportation requirements.

The new signals were originally planned to be brought online along with the next generation of GPS operating software, known as Operational Control Segment Next Generation or OCX, but last Autumn, General William Shelton, commander of Air Force Space Command, challenged the SMC program office and 2 SOPS to find a way to bring the capability online using GPS’s current operating software.

“This was an unprecedented effort for the development team,” Ste. Marie said. “They developed a creative and specialized suite of software to make the system functional.”

As Ste. Marie explains, adding another civilian navigational signal is important for civilian users because it creates a more accurate, robust and agile effect.

“Having two signals available allows a user to correct for sources of error like the ionosphere,” he said. “For example, imagine viewing a straw in a glass of water; it seems to diffract a little bit. Well, that’s what happens with a GPS signal — it diffracts a little bit. But, if you have two straws, you can measure that diffraction and correct for it.”

For the time being, both signals are considered pre-operational. The L5 signal is also labeled unhealthy to users.

“They’re set that way because the civilian user community needs time to really understand the signal, and what it is doing, so they can develop appropriate receiver equipment,” said. Lt. Col. Matthew Brandt, 2 SOPS director of operations. “With L5 set to unhealthy, we’re really just telling developers that they can now build a receiver that can pick up the signal, but we’re also warning civilian users not to use the signal to land a plane or guide a car.”

Ste. Marie explained that both signals will eventually transition into operational status, while L5 will be set to healthy at a future date yet to be determined.

Though the team members put in a tremendous effort to implement the project during the pre-operational period, their work continues. Every 2 and 19 SOPS payload operator must complete specialized training and certification.

The squadrons’ navigation analysts and engineers also must monitor the generation and upload transmission of these messages.

“From a local 50th perspective, along with the broader MAJCOM team, it was definitely a 50th Operations Group-wide effort to include the 50th Operations Support Squadron and the 50th Operations Group Standardization and Evaluation Division,” Ste. Marie said. “Delivering these new signals required a whole new set of skills and knowledge during the past six months in order to get our operators trained to accomplish this important new mission.”

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