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--- sdk:gps-udp-client-gnsstogps [2019/07/12 11:19]
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+++ sdk:gps-udp-client-gnsstogps [2019/11/28 11:26]
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@@ Line 1: / Line 1: @@
+====== Background ======
+GPS was the first Global Navigation Satellite System (GNSS) and the term GPS is often used as a synonym for GNSS.
+Older software often only checks for NMEA 0183 sentences starting with <nowiki>"$GP"</nowiki> (= GPS only) instead of looking for  all GNSS systems.
+Newer GNSS receivers often use multiple GNSS systems and therefore <nowiki>"$GN"</nowiki> is used (<nowiki>"$GNRMC..."</nowiki>) if it recives a combination of GPS, Galileo and GLONASS signals.
+It would be better to us instead of <nowiki>"$GPRMC"</nowiki> either <nowiki>"$G.RMC"</nowiki> ("." = anychar) for using GPS, Galileo and/or GLONASS (GNSS) or even <nowiki>"$..RMC"</nowiki> which means any source.
+<code>
+NMEA 0183 sentence "$XXYYY..." explanation:
+"$" = Start
+"XX" = Source device (https://de.wikipedia.org/wiki/NMEA_0183#Ger%C3%A4te-IDs)
+	BD = Beidu
+	GA = Galileo
+	GL = GLONASS
+	GP = GPS
+	GN = GNSS position fix from more than one constellation (eg. GPS + GLONASS)
+"YYY" = Record
+	RMC = Recommended Minimum Sentence C (used in most cases)
+	GGA = Global Positioning System Fix Data
+	GNS = GNSS fixed data
+	GLL = Geographic Position - Latitude/Longitude
+	...
+Source: https://de.wikipedia.org/wiki/NMEA_0183
+</code>
 ====== SDK Script gps-udp-client-GNSStoGPS.are ======
 <code c gps-udp-client-gnsstogps.are>