John W. Lavrakas, Advanced Research Corporation

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Today, the world is experiencing a jump in GNSS/RNSS services, advancing beyond the decades-long monopoly of GPS and GLONASS in providing worldwide PNT. BeiDou Navigation Satellite System (BDS) now offers global services, and Galileo is not far behind. QZSS and NavIC are beginning to offer regional services. We are in a transition period as the new satellite navigation service providers complete their move from initial operation to full operation over the next several years. While each system provides PNT services, these services differ in implementation and capabilities, in signals, codes, navigation data, data authentication levels, and ancillary services. This paper examines the core service standards addressing accuracy, availability, continuity, integrity, and coverage for each of the various systems, providing a brief historical perspective, and a look at where we are today in implementing and monitoring these services. The analysis includes a table comparing and contrasting the service standards for each of the systems. The paper provides background on standards, how they came about, and reports on their value in ensuring users have a dependable, repeatable service, able to serve as a basis for certification of safety of life PNT services. The paper reports on steps being taken by the United Nations International Committee on GNSS (ICG) to encourage a core set of standards for each GNSS with harmonized definitions and transparent methodologies. It presents steps being taken to verify the performance standards commitments, and examines recent failure events in GPS and Galileo, assessing how they reflect on the service commitments. The paper summarizes the progress to date in implementing the ICG guidelines and provides a look at future steps to be taken in implementing GNSS/RNSS performance standards. In this article, the term “performance standard” is used. Some organizations refer to these documents by other terms, such as a service standard, open service standard, or service definition document. For the purpose of this article these terms are considered synonymous.