GPS III finally aloft, benefits on the way

SpaceX’s Falcon 9 rocket orbited the first GPS III satellite on Dec. 23, 2018. (Photo: SpaceX)

On December 23, the first GPS III satellite entered an orbit around Earth, after a five-day delay. This first of a new breed of GPS satellite also experienced a four-year delay, with its original launch scheduled for 2014.

While the system has experienced more than its share of problems, at the start of a new year I want to focus on the benefits to come.

Few of us realized how much our lives would change when the first GPS satellite was launched in 1978. GPS III could bring about a similar trajectory of changes. Civilians can expect a more reliable and accurate service. The smartphone message “searching for signal” could become a dim memory.

GPS III signals will be three times more accurate than the current GPS Block II models. The navigation payload has more than three times reduction in range error and up to eight times increase in power — its signals should be much easier to pick up under tree canopy, within urban canyons and inside buildings.

GPS III also has four civilian signals. The L1C signal is interoperable with international GNSS, meaning users can receive signals from any country’s satellites. Also, using two civilian signals means GPS III can directly detect and correct ionospheric errors.

In addition to a standard wide-angle antenna for broad coverage, the GPS III satellites include a high-gain directional antenna that will operate with 100 times (+20 dB) the power of the wide-angle antenna, and will be exclusively for use with M-code (military) transmissions. This directional antenna’s spot beam covers an area 120 miles at high power— boosting the power of military GPS signals by 100 times in specific regions, making military GPS even harder to jam.

These advantages may not reach the battlefield for a decade. The new constellation will take time to build. The GPS III constellation is projected to be fully capable in June 2023, when 10 Block IIIA satellites are expected to be in orbit. Ten follow-on satellites are planned to be placed into orbit from 2026 to 2034.

Back here on Earth, equipment makers will need time to develop and supply warfighters with military GPS user equipment (MGUE) that can take advantage of all that GPS III has to offer.