The PTTI 2011 Tutorials Session will take place on Monday, November 14, 2011. The Tutorials are intended for engineers, mathematicians, scientists or anyone who is new to the field of PTTI, as well as those who have been a part of the PTTI community. For information regarding the Tutorials, please contact Gregory Weaver (gregory.weaver@jhuapl.edu).
The registration fee for the PTTI 2011 Tutorials Session is $250 if received/postmarked on or before October 14 and $300 after October 14. The fee includes breakfast, lunch and a copy of the Tutorials presentations (notebook and CD).
Earth Orientation, Reference Systems and Time Scales
Richard Gross, Jet Propulsion Laboratory
Ken Senior, Naval Research Laboratory
This is a two-part tutorial, but in many ways interrelated. For precise terrestrial navigation, a system of reference frames must be devised which coordinately maps the surface of the Earth into positional information with respect to navigational aids such as the Sun, stars and most recently GNSS spacecraft. But, all these objects have independent dynamic motions that must be routinely estimated through a variety of models to keep their associated reference frame coordinate. In this manner, timescales such as UT1 and UTC are maintained to provide a currency that allows information about reference system dynamics to be transferred for corrected Earth orientation. This tutorial will explain the most prominent reference systems derived from celestial mechanics, the development of inertial frames of reference and the incorporation of relativistic effects. From this discussion, the attendee should better realize the importance of timekeeping and the maintenance of the International recognized timescales, which reside at the center of modern PNT methodologies.
Dissemination Technologies for Coordinated Timekeeping
Judah Levine, National Institute of Standards and Technology
Dissemination is typically a broadcast of precise timekeeping to users for the coordination of often spatially disparate effects measurements, temporal logging of data and activity planning. The variety of methods currently in use from fiber-based optical links to GNSS time recovery to Network Time Protocol to WWVB short-wave radio signaling represent just a small set of prominent and effective dissemination systems. The issue that most often arises is which one is the best choice in terms of local availability, infrastructure development and required timekeeping performance. This tutorial should offer the attendee a survey of existing and emerging dissemination systems with an emphasis toward requirements planning and trade analysis.
Space Weather and PTTI Signal Propagation
Mike Kelly, Johns Hopkins University Applied Physics Laboratory
Space weather describes the dynamic interaction between the Earth's magnetic field and the Sun's output of charged particles, known as the solar wind. This dynamic is most notably driven by the Sun's cyclic eleven year variation in solar wind activity. The current state of space weather is expected to intensify over the next several years with the imminent increase in solar activity as the sun enters its next maximal phase. An emerging realization is that, during this last epoch of solar minimum, the world's society has become ever more dependent on space-based PNT and communication systems. This tutorial should inform the attendee on the expected effects and degradation of signal fidelity for space-based PNT systems which propagate through the Earth's ionosphere. A notional understanding of possible mitigations to operational disruption will be discussed.
Technology Survey of Atomic Frequency Standards and Clocks
Robert Tjoelker, Jet Propulsion Laboratory
The term "atomic clock" is often used generically in system architectures, implying a high performance level of timekeeping accuracy. In practice, atomic frequency standards and clocks provide a range of capabilities to address a broad set of orthogonal requirements. The tutorial will provide a survey of the taxonomy of atomic clock technology and enhance attendee understanding toward the current variety of devices and development efforts.
GNSS and PTTI System Diversity and Interoperability
Edward Powers, U.S. Naval Observatory
Material will cover the variety of GNSS and space-based PTTI systems either deployed or in development to enhance familiarity with system performance, signal qualities and trades. The tutorial should provide the attendee with a clear notion of the reasoning for GNSS diversity and the emerging advantages offered by interoperability.
