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barbeau / gpstest

The #1 open-source Android GNSS/GPS test program
Apache License 2.0
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Update PRN numbers - include Beidou #54

Closed barbeau closed 9 years ago

barbeau commented 9 years ago

Looks like Beidou PRN numbers may be 201-214, which would overlap with the ones we're currently using for QZSS (see #52). We should fix this.

See below post for details and screenshots: https://groups.google.com/forum/#!topic/gpstest_android/rRn3UChTSr4

barbeau commented 9 years ago

Here's the feedback from the user:

I to you gave the reference where Japanese wrote that they have a range of satellites with PRN 183-192 or 193-202. As shows the tablet, Beidou uses PRN satellites since 201-202!!! Having read on the Internet I understood that it is possible to understand whom whose satellite only in RAW NMEA log. But unfortunately I didn't find the program which would collect completely all log. The majority of programs show only GPS or GLONASS the log. Also I saw a difference in operation of MTK and Qualcom chips. The MTK chip, judging by your program uses all visible satellites equally. Qualcomm the chip a specification for calculation uses GPS satellites, other data uses periodically for adjustment. For example on the dug-out district when I don't see a consistent reception sometimes in your program of Beidou or Glonass satellites. But in the city district when reception worsens, the Qualcomm chip starts using all satellites seen to it actively. Probably for economy of energy.

I still will look for information on PRN Beidou satellites but practically my tablet sees Beidou PRN 201-214.

Beidou can correct the PRN 201-214 list so far as. I will look for reliable information on PRN. Though with Chinese it is difficult.

barbeau commented 9 years ago

BeiDou in its final configuration will consist of 35 satellites, 5 geostationary and 30 MEO (source). Some practical measurements (though not on Android) are here, showing values in the range 201–210. I have personally seen PRN 211 reported on a co-worker's Android phone.

Apparently the PRNs start at 200 or 201, hence the upper boundary is likely to be 234 or 235. Currently only 16 satellites are up, 2 of which are not operational, hence you will never encounter most of these numbers until more satellites are launched. 201–205 seems to be the range for the geostationary satellites, thus you might not encounter any of these unless you are within their coverage range.

Edit: NMEA seems to have created a de-facto standard for satellite IDs, which pretty much matches what has been seen on Android. I have tried to put together a list of all ranges currently in use here.

From: http://stackoverflow.com/a/25122012/937715

NMEA IDs can be roughly divided into the following ranges:

  • 1–32: GPS
  • 33–54: Various SBAS systems (EGNOS, WAAS, SDCM, GAGAN, MSAS) – some IDs still unused
  • 55–64: not used (might be assigned to further SBAS systems)
  • 65–88: GLONASS
  • 89–96: GLONASS (future extensions?)
  • 97–192: not used
  • 193–195: QZSS
  • 196–200: QZSS (future extensions?)
  • 201–235: Beidou

From: https://github.com/mvglasow/satstat/wiki/NMEA-IDs