Fall is finally here and to celebrate we have released a new version of SDX. Release 17.10 of SDX adds support for GPS L5, timing improvements to synchronize your GNSS simulation with your test environment, and enhanced features for BeiDou GNSS simulation. Read on to learn more about this exciting new release of SDX, the software-defined GNSS simulator with sky-high performance and unmatched flexibility.
SDX support for GPS L5
If you already know everything there is to know about L5, you can safely skip to the release details. Otherwise, we recommend that you read on.
A bit of history about GPS
GPS has been in development since the early 1970s, following early experiment from the US Navy with positioning using Doppler from Satellites. The US Department of Defense (DoD) wanted a robust positioning system and developed GPS as we know it during the 70s throughout the 90s.
From their early beginnings, GPS satellites were designed to broadcast multiple signals. Even the first GPS satellites were broadcasting two signals:
- C/A (Coarse/Acquisition) on L1 frequency. This was called the Standard Positioning Service, or SPS for short.
- P on L1 and L2 frequency. This signal was restricted for use by the US military, and was and thus encrypted when modulated with the W-code to create the P(Y) encrypted signal. This became the Precise Positioning Service, or PPS.
The Standard Service, however, was initially degraded by a measure called “Selective Availability” (or SA for short) for national security reasons. With positioning errors ranging in the dozens of meters, accurate positioning and navigation using the GPS public signal was impossible.
Although GPS was initially intended for military usage only, the KAL Flight 007 incident in the 1980s is credited with triggering a chain of events that led US political leaders to consider evolving GPS into a dual-use (i.e., military and civilian) positioning system. In the 1980s and 1990s, plans to improve the civilian availability of GPS were made, but Selective Availability remained in function. In 1995, after many years in development, GPS FOC (Full Operational Capability) was declared by the US Air Force, and soon after, an official GPS modernization plan was approved by the US Congress. Finally, on May 2, 2000, “Selective Availability” on L1 CA was discontinued, which allowed widespread civilian use of GPS to begin. Consumer devices using the GPS L1 CA signal were being commercialized and quickly adopted by the public. Meanwhile, modernization was slowly taking place.
Over the years, and even before FOC was achieved, GPS satellites were improved. Nowadays, various satellite models are currently in operation, while others are planned for launch.
The 1998 GPS modernization plan is still being implemented and includes the addition of multiple new civilian signals dedicated to improving the reliability and accuracy of GPS for the general public. Three public signals are part of this modernization (L1C, L2C, and L5) along with the implementation of an improved military signal, M-code. In 2004, the first modernized GPS satellite (Block IIR-M) was launched, and it soon began transmitting a second civilian signal (L2C).