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# UBLOX GPS chip output GGA message, the maximum number of satellites used is 12

edited October 2018 in General
I compared the GGA messages output by ublox GPS and xgps160. The number of satellites UBOX is using is 0-12. The maximum is 12, and xgps160 does not have this limit.
However, the number of satellites that ublox actually uses for calculation is greater than 12, which can be read from GSA messages. Therefore, it is recommended to read the number of locked satellites from the GSA message.

UBLOX
\$GNGGA,021919.50,3200.03756,N,11706.73814,E,2,12,0.61,58.8,M,-2.8,M,,0000*6E
\$GNGSA,A,3,42,05,06,12,19,23,50,09,25,02,17,,1.11,0.61,0.93*10
\$GNGSA,A,3,88,81,67,66,87,65,8,,,,,,1.11,0.61

XGPS160
'\$GPGGA,022821.200,3200.03864,N,11706.73771,E,1,18,0.6,63.4,M,-4.4,M,,0000*7A
\$GPGSA,A,3,12,06,09,05,193,02,23,19,17,25,13,,1.0,0.6,0.8*07
\$GNGSA,A,3,81,87,66,65,67,88,82,,,,,,1.0,0.6,0.8*2D

## Comments

• Hi, this affects only the displayed number of satellites. The precision of data is not affected. It's just a number that is shown on the screen... You can even just filter out all of the *GSA and *GSV sentences if you like. The coordinates are taken from *GGA or *RMC fields, and they are used just as they are reported in those sentences.
• @aol In the case of sending GSA packets, it is recommended to obtain the data using the number of satellites from the GSA packets first. This is absolutely accurate. If no GSA message is sent, it is obtained from GGA. If you only get it from GGA, it is not accurate for ublox. This is my suggestion because I want to see accurate data. I don't want to be cheated. I have been using ublox for more than a year, and I have always thought that the performance of ublox is worse than MTK3333. Actually, I am wrong with ublox. Ublox is a low cost solution for DIY.
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