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GeoscienceAustralia / ginan

The Australian Government, through Positioning Australia (part of Geoscience Australia), is funding the design, development and operational service of a Global Navigation Satellite System (GNSS) position correction system - the Ginan service and toolkit. The application of the Ginan correction service by a GNSS device has the potential to increase positioning accuracy from meters to centimetres across Australia. The suite of software systems in this repository (the Ginan toolkit) will be used to create the service. It is available now under an open source licence. Ginan will give individuals and organisations no-cost access to the Ginan software and service as a public good.
https://geoscienceaustralia.github.io/ginan/
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How can NMEA be fed as the realtime stream in satellite_data? #84

Closed javadtaghia closed 2 months ago

javadtaghia commented 5 months ago

Thanks for the great product. I have a question regarding live corrections that can be done using Ginan.

Can Ginan be used to use the live NTRIP published at ntrip.data.gnss.ga.gov.au as gnss_observation and improve the input from a GNSS receiver that sends NMEA?

If yes, how can it be configured to accept real time data from a GNSS receiver? If the receiver sends in NMEA, is it acceptable to Ginan?

I found an example r_ppp_example.yaml (https://github.com/GeoscienceAustralia/ginan/blob/main/exampleConfigs/rt_ppp_example.yaml)

satellite data still is coming from ntrip.data.gnss.ga.gov.au and have offset APC.

How can I change the satellite_data to look into a GNSS receiver locally connected to a USB sending NMEA?

ronaldmaj commented 5 months ago

Hi javadtaghia,

Thanks for your question. Ginan requires the raw ranging observation data in order to process positions. This can come from RINEX data files or RTCM streams but those observations are critical. If you are using Ginan with a correction stream, you will also need to connect to raw observations.

NMEA data are post-processed and provide a solution to observations that were used previously, i.e. they provide positions (along with datestamps and other information) after processing observation data. Therefore, NMEA data are not raw ranging observations and generally cannot be used to carry out the type of analysis you are looking at. You can process real-time data from a GNSS receiver, but that receiver will need to output the raw observations which you can feed into Ginan. This may be useful information as well: https://gis.stackexchange.com/questions/274965/postprocessing-with-nmea-data-if-no-rinex-data-is-available

Hope that helps. If you have any further questions or queries, please let us know :)