After enable Beidou NMEA, there are always multiple PQGSV/GSA sentences in one time report with different content.
For example:
$PQGSV,1,1,03,01,57,120,47,02,24,175,48,03,68,067,46,0,55F
$PQGSV,2,1,07,01,49,03,47,04,45,07,46,0,463
$PQGSV,2,2,07,20,54,27,52,30,40,0,46A
$PQGSA,A,2,1.9,1.7,0.9,43A
$PQGSA,A,2,1.9,1.7,0.9,5*3B
The first sentence says there are 3 satellites in view, but 2nd one says there are 7.
What does that mean and how should I parse satellite information with it.
Ran into this recently as well, my interpretation is that there is an extra field, as per NMEA 4.1 spec, stating the GPS system id there, right before the checksum.
It’s differs, 4 and 5 for those sentences. 4 is BeiDou and 5 is QZSS. Sharing the same prefix, but two different satellite systems (GNSS) regardless. Similar to GNGNS system id field.
A bit confusing as for the GSV sentence it shouldn’t be system id but signal id. I get both!
Here is what I get from a EC25:
$PQGSA,A,2,27,30,,,,,,,,,,,1.6,1.3,0.9,4*37 // 4 -> BeiDou, 2 active satellites
$PQGSA,A,2,,,,,,,,,,,,,1.6,1.3,0.9,5*30 // 5 -> QZSS, 0 active satellites
$PQGSV,3,1,11,27,09,184,30,30,40,230,34,02,,,,05,12,127,,0,4*5A // 4 -> BeiDou, 11 satellites in view
$PQGSV,3,2,11,06,09,043,,09,34,053,,16,13,043,,20,21,251,,0,4*6F
$PQGSV,3,3,11,23,04,127,,24,14,026,,29,34,302,,0,4*50
$PQGSV,1,1,01,03,05,047,,0,5*5E //5 -> QZSS 1 satelllite in view