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> The radio aspects are straight forward. (...) People have had Iridium satphones from even in the last century Sorry, but this whole thing is about your regul

by haspok 3y ago

> The radio aspects are straight forward. (...) People have had Iridium satphones from even in the last century Sorry, but this whole thing is about your regular mobile phone transmitting a signal to a satellite, which was NOT designed to do that. To call this "straightforward" sounds a bit of an oversimplification to me.

ChuckMcM 3y ago
Disclosure here, I know a lot about radio, less about the implementation in current mobile handsets. Mobile handset signals reach space. There are satellites in orbit that, amongst other things, look for them. It is just one of the ways an agency with space assets can use them to surveil places. Mobile handsets are programmed with a certain expectation about how cell towers will present themselves to the phone (I know this from working with early Android builds inside Google). They make choices about which tower to use on a moment by moment basis. They also have code that tries to keep them from "annoying" cell towers when people forget to switch them off on planes. Basically heuristics around how often cell towers are showing up, what is their signal level, how is it changing over time, what's my GPS altitude and velocity, etc. My understanding from an engineer who worked at Qualcomm with T-mobile on their Starlink demonstration[1] (the modem stuff mostly) was that primarily the changes were around cell tower policy not around changes in the signal. (yes, the radio was updated to tune to Starlink's uplink/downlink frequencies as a possible cell tower). His summary was the effort was zero hardware changes, just updates to the software on the phone modem/radio and the Starlink hardware in space. If there are HW changes that will make it work better, I expect we will see phones marketed as "satellite ready!" in the future. Apple has already started doing some of that with the iPhone. [1] I met this guy at a swap meet selling test equipment so I could not swear to his bonafides but he certainly understood the radio concepts.
- haspok 3y ago
  Thank you, very insightful.

by haspok 3y ago

ChuckMcM 3y ago

Disclosure here, I know a lot about radio, less about the implementation in current mobile handsets. Mobile handset signals reach space. There are satellites in orbit that, amongst other things, look for them. It is just one of the ways an agency with space assets can use them to surveil places. Mobile handsets are programmed with a certain expectation about how cell towers will present themselves to the phone (I know this from working with early Android builds inside Google). They make choices about which tower to use on a moment by moment basis. They also have code that tries to keep them from "annoying" cell towers when people forget to switch them off on planes. Basically heuristics around how often cell towers are showing up, what is their signal level, how is it changing over time, what's my GPS altitude and velocity, etc. My understanding from an engineer who worked at Qualcomm with T-mobile on their Starlink demonstration[1] (the modem stuff mostly) was that primarily the changes were around cell tower policy not around changes in the signal. (yes, the radio was updated to tune to Starlink's uplink/downlink frequencies as a possible cell tower). His summary was the effort was zero hardware changes, just updates to the software on the phone modem/radio and the Starlink hardware in space. If there are HW changes that will make it work better, I expect we will see phones marketed as "satellite ready!" in the future. Apple has already started doing some of that with the iPhone. [1] I met this guy at a swap meet selling test equipment so I could not swear to his bonafides but he certainly understood the radio concepts.

haspok 3y ago
Thank you, very insightful.