Performance of Distributing Digital Attitude Data in Maritime Navigation

Lynetta Grajeda, Michael Ferguson, and Ceferino T. Fajardo III

Peer Reviewed

Abstract:	One reason that Synchro interfaces have lasted this long is because the technology for transferring real-time navigation data works with only a slight latency due to the time travel of electric current through the wires, but otherwise without any additional introduced errors. Of course, the downside of Synchro interfaces is the large size, weight, and power it requires to operate. With digital technology and especially with high speed networks, the ability to convert sourced analog to digital navigation data, transport it over a fast controlled network, and then back to analog for the user system dramatically reduces the size, weight, and power requirement. However, with the digital conversion and the limitations of standard transport network technology, several issues have been introduced in the form of latencies, jitter, and drift (a.k.a. wander). These digital errors have varying impacts on the navigation systems based on the applied use of the data, where simple plotting of a position overlay on a map is not as critical as trying to maintain a stable base for a mechanically pointing device while the ship is rocking and rolling. Therefore, there is a definite need to understand the required performance of the navigation data user systems, which in turn helps in defining the objective requirements to deliver navigation data that will enable that performance. Unfortunately, some requirements have not been described properly, leading to ambiguity in their interpretation, which then casts the tested performance into question about the actual accuracy of the system of systems. This paper will explore this topic as it relates to the distribution of navigation data, mainly attitude, in digital form from the sensor system to the user system. It will clarify some of the current ambiguous performance requirements, and then analyze some real data to compare with the expected results using the more explicit criteria. The findings are mixed in a way that some aspects meet or beat the expectations, while others don’t, but their significance is in the improved visibility into the root causes affecting the performance of distributing digital maritime navigation data.
Published in:	Proceedings of the ION 2017 Pacific PNT Meeting May 1 - 4, 2017 Marriott Waikiki Beach Resort & Spa Honolulu, Hawaii
Pages:	162 - 166
Cite this article:	Grajeda, Lynetta, Ferguson, Michael, Fajardo, Ceferino T., III, "Performance of Distributing Digital Attitude Data in Maritime Navigation," Proceedings of the ION 2017 Pacific PNT Meeting, Honolulu, Hawaii, May 2017, pp. 162-166. https://doi.org/10.33012/2017.15046
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