Inside GNSS Media & Research

NOV-DEC 2017

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50 Inside GNSS N O V E M B E R / D E C E M B E R 2 0 1 7 G NSS SDRs are a rapidly advanc- i ng a re a i n GNS S re c eiver research and design. The last few years have brought tremendous growth in this field. Universities and other research institutions have devel- oped a nd demonst rated adva nced capabilities, particularly with respect to mu lt i- c on s t e l l at ion GNS S a nd GNSS-plus-multi-sensor navigation processing for challenging environ- ments. The recent commercial avail- ability of multi-sensor data collection equipment, development platforms a nd open-source sof t wa re projects have catalyzed this rapid pace of inno- vation. Indeed, SDR will likely become a significant commercial GNSS receiver architecture by the end of this decade due to today's ongoing deployment of multiple global and regional satnav constellations with their diverse signal structures, and rapid advancements in parallel low-power processors and inex- pensive sensors. Non-realtime SDR operational sce- narios involve storage and post-pro- cessing of samples. ese sampled data files can also be used in radio frequency (RF) playback systems for GNSS receiver test and evaluation in the lab. Post-pro- cessing and/or playback requires several generic front-end parameters such as RF and intermediate frequency (IF) center frequencies, sample rate, file format, as well as GNSS-specific information such as antenna location and type. We define this information as GNSS SDR meta- data. Manual transfer of metadata is the method predominantly used today – a process that is cumbersome and error prone to say the least. No established method exists to exchange this metadata automatically. During the ION GNSS+ 2013 con- ference, a group of attendees discussed the need for a formal standard for the exchange of GNSS SDR metadata. is group identified the following benefits of engaging in this activity at the present: The past several years has seen a proliferation of software defined radio (SDR) data collection systems and processing platforms designed for GNSS receiver applications or those that support GNSS bands. For post-processing, correctly interpreting the GNSS SDR sampled datasets produced or consumed by these systems has historically been a cumbersome and error-prone process. These systems necessarily produce datasets of various formats, the subtleties of which are often lost in translation when communicating between the producer and consumer of these datasets. This article describes the Institute of Navigation's GNSS SDR metadata standard and associated open-source software project. The initial public comment process for this free and open standard is currently active until December 31, 2017. Readers are encouraged to submit feedback at ION STANDARDS The Institute of Navigation's GNSS SDR Metadata Standard JAMES CURRAN EUROPEAN SPACE AGENCY MARKEL ARIZABALETA UNIVERSITÄT DER BUNDESWEHR MÜNCHEN THOMAS PANY UNIVERSITÄT DER BUNDESWEHR MÜNCHEN SANJEEV GUNAWARDENA AIR FORCE INSTITUTE OF TECHNOLOGY

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