ION Software-Defined Radio Metadata Standard Final Report

The ION GNSS SDR Metadata Standard describes the formatting and other essential PNT-related parameters of sampled data streams and files. This allows processors to seamlessly consume such data without the need to input these parameters manually. The technical development phase of the initial version of the standard has now been deemed complete and is currently undergoing the last remaining procedural steps towards adoption as a formal standard by the Institute of Navigation. This paper reports on the activities of the working group since September 2018 and summarizes the final products of the standard. It also reports on examples of early adoption by academic, research, and open source SDR projects. This includes an example where, as intended, capabilities covered in the standard have been expanded to describe custom data embedded within sampled data streams. Also included is an example where the standard is used to describe non-GNSS data. Several examples of commercial adoption are also documented in this paper. The standard website (sdr.ion.org) includes a repository containing SDR files of various topologies and formats. The working group is currently in the process of providing the satnav observables for these datasets using well-known SDRs in order to serve as a reference for those working to adopt the standard products into their own software projects. This paper also includes results from this effort. 32nd International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GNSS+ 2019), Miami, Florida, September 16-20, 2019 3785 https://doi.org/10.33012/2019.17027 INTRODUCTION The ION GNSS SDR Metadata Standard arose out of a need that was first discussed at the ION GNSS+ 2013 meeting in Nashville Tennessee, to come up with a standard way to describe the sampled data file formatting and other important parameters relevant to satnav SDR processing (referred to as GNSS SDR metadata), in such a way that an SDR could conceptually handle any of these files without having to manually enter these parameters. After 6 years of voluntary effort by the Standard Working Group, this vision has largely been realized and this free and open standard development has been deemed complete. All technical documentation and reports generated as part of this development can be found in http://sdr.ion.org/presentations-and-publications.html. The draft standard document can be found in https://github.com/IonMetadataWorkingGroup/GNSS-Metadata-Standard/tree/master/Specifications/documentation. This paper represents the final report on this effort. Activities since September 2018 and the final steps toward formal ratification are summarized below. An overview of the normative reference software and current status is described next. The remainder of the paper reports on current adoption and use cases of the standard by academia and research organizations, as well as availability of commercial products that have adopted the standard. Finally, early results on the effort to provide observation data to go with the test and verification datasets found in the ION SDR data repository are presented. STATUS REPORT (ACTIVITIES SINCE SEPTEMBER 2018) The second public request for comments (RFC2) was launched on September 24, 2018. Notice of RFC2 appeared in the ION GNSS+ 2018 printed program, was emailed to the ION distribution list (9,296 recipients), appeared in the Fall 2018 issue of the ION Newsletter and was also posted on the ION website. The deadline for submitting comments was December 31, 2018. The working group received a total of eight comments for RFC2. These were mostly related to minor issues in the standard document and were resolved through a revision. Letters acknowledging their comments and the working group’s resolutions were sent to each RFC2 respondent. The comments, and the working group’s responses and resolutions are reported in http://sdr.ion.org/RFC2_Comments_Responses.html. During this period the working group also made minor revisions to the normative software and merged the development branch (which included revisions resulting from RFC2) into the master branch. More details on the normative software are given in the next section. During this period the working group also made minor revisions to some of the metadata files associated with the reference datasets: http://sdr.ion.org/api-sample-data.html Following the activities summarized above, the standard development effort was deemed complete. On August 21, an electronic poll was sent out to each voting member of the working group seeking their input on proceeding to the next step: the ION legal review, as stipulated in the terms of reference http://sdr.ion.org/TermsOfReference_042114.pdf. This procedure was discussed at our working group meeting during ION GNSS+ 2018: https://s3.amazonaws.com/sdr.ion.org/Presentations_and_Publications/2018/WG-Presentation-Minutes-Attendees-2018.pdf. A reminder message was sent on August 29 to 41 contacts who had not yet voted, and this poll concluded on September 4, 2019. Out of the 57 voting members, there were 27 approvals and no disapprovals. However, this equates to a participation of 46%. During the ION GNSS+ meeting, informal conversations with voting members revealed that some had not gotten around to voting and others were on summer vacation and had not seen the email in time to vote. For these reasons, during our most recent meeting it was decided to re-open the vote to those who did not originally participate in order to increase participation. This new poll is planned to begin on or near October 7, 2019. Note: the working group is comprised of satnav SDR subject matter experts from across the globe representing academia, government, and industry. In a few cases more than one member is affiliated with the same organization (e.g. due to change of employment since this effort commenced). A voting member is one that is designated to represent his/her affiliated organization. Next Steps Following the approval of the standard by a majority of the working group voting membership, the next step is the legal review by ION-appointed council. The legal review will scrutinize all documentation and records generated since this effort was started to determine whether all activities were performed objectively with adequate opportunity for public participation and discourse. After the legal review, that report and the standard products will be presented to ION Council for adoption as a formal ION standard. Once adopted, the standard will be made formal (as opposed to the current draft status) with revision number 1.0.