Add support for Beidou-3 B2b signal

[Narugakuruga]

Mediatek Demisey 9200 add BDS-3 B2b and Galileo E5b signal supports.
B2b is broadcasted by all BDS-3 MEO/IGSO satellites (C19-C46) and PPP-B2b is broadcasted by BDS-3 GEO satellites (C59-C62).
Would be cool to see the new signal in action!

[barbeau]

Interesting! Thanks for sharing this. Agreed, it would be nice to see the b signals on real devices.

The good news is that GPSTest will already label Galileo E5b correctly:
https://github.com/barbeau/gpstest/blob/master/library/src/main/java/com/android/gpstest/library/util/CarrierFreqUtils.java#L177

Looks like BDS-3 B2b still needs to be labeled correctly, so I'll work on that:
https://github.com/barbeau/gpstest/blob/master/library/src/main/java/com/android/gpstest/library/util/CarrierFreqUtils.java#L135

[Narugakuruga]

Would be nice to test it out ☺️.
I will check with a phone with D9200+ chipset someday

[Narugakuruga]

I'm very curious to find out these Beidou-3 GEO satellites use B1l frequency for navigation service, B1C and B2a frequency for SBAS service. Their B2b is for high accuracy PPP measurement.

While all these bands of other Beidou-3 sats is only for common navigation.

So every GEO satellites serve 3 functions. That's interesting.

But right now the SBAS service is in test stage. Not for public use I think....

[Narugakuruga]

Screenshot with Redmi K60 Ultra (D9200+ Soc)

[Narugakuruga]

My test shows B2b is on 1207.14 MHz band. (Constellation type 5 for BDS right? )
Which is the same old "B2" frequency that gpstest already labeled.
It's weird it doesn't shows up as B2 yet.

[Narugakuruga]

According to BDS official website.
B2b is expected to fully replace B2 as they use same 1207.14Mhz (maybe even un-interoperable too?)

[barbeau]

My test shows B2b is on 1207.14 MHz band. (Constellation type 5 for BDS right? )

Nice! What device is the screenshot from?

[Narugakuruga]

Redmi K60 Ultra in China, aka Xiaomi 13T Pro :)
Maybe it's because android api couldn't report B2b signal? I guess.
So inside the GNSS chip it's using b2b to calculate location and PPP correction, but can't be read by android api?

[Narugakuruga]

In GNSSLoger, BDS's 1207.14 MHz only shows up in MeasurementProviderMeasurement.
But it would not display in Status SATELLITE_STATUS

[Narugakuruga]

Ahh I see. Gnss logger can shows B2b normally.

Apparently mediatek 9200 chip only received B2b exclusively from 3 satellite. So it's easy to miss it.

Last time when I doing the measurement it was indoor, so I didn't receive the signal.

So maybe Gpstest can show that too. We just have to rename B2 to B2b

[barbeau]

Closed by #657