| > it still requires an initial lock to GPS before feeding them in Is there any technical reason, or is it just protectionism? (as in, no GPS lock? No lock at all, even if Galileo and Glonass are 100% fine!) > Beidou is still banned and blocked in firmware while in US even though the satellites are broadcasting, since this constellation lacks US approval Is it legal to use a Xiaomi phone in Wifi only mode with Beidou GNSS? > Here's some slides about BeiDou's technical details, specifically note the 2-way messaging Super interesting, ty! I see interesting details like "Horizontally positioning accuracy is about 1.5m" so it should be better than GPS! Also, it supports 300k SMS/h with a coverage over Japan, India and Thailand! I would love to play with Beidou! |
No technical reason. It's a mixture of both legitimate concern for public safety (they are newer constellations with a shorter reliability track record) and the uh, more political concerns over privacy and national security.
I wouldn't be surprised if China does the inverse considering their motivations for developing BeiDou were first and foremost to stop the US jamming the GPS receivers on their missiles. My immediate thought with the decay of US/Russia relations was that it might be a good idea to throw a switch to disable GLONASS in case they start transmitting bogus signals. My assumption is with the 'GPS first' policy, the receiver shouldn't mix in less accurate data, but without documentation I'm not sure.
Personally I'm all for having options and I have come to respect Galileo for being civilian system, rather than a military system. More than anything I want the choice to be able to enable and disable whatever constellations I want and not deal with the bullshit that is Qualcomm's undocumented GNSS receiver firmware.
> Is it legal to use a Xiaomi phone in Wifi only mode with Beidou GNSS?
It's legal to use if it doesn't transmit on someone else's licensed spectrum. It's illegal to sell in the US as a navigation receiver (EDIT: without it being disabled in firmware). But you are free to do whatever you want with captured signals with only a very few restrictions (like sniffing cordless phone bands). I've even sniffed pager networks so I could track COVID cases coming in, afaik it's only illegal if I share what I see.
> I would love to play with Beidou!
Same. I told a GPS launch commander I'd like to play with their system and he got incredibly butthurt. I told him to stop being a bitch and either make the US system better or stop excluding civvies from using it to its fullest potential. There's no commercial alternatives in the US as all commercial satellite projects get heavily subsidized by the US military and they don't want competitors.