iPhone 14 contains an “SOS” feature, which allows it to communicate with a satellite network during an emergency (if all other wifi/cell networks are unavailable).
Can someone explain to me how the new iPhone transmits these mini SMS messages to the satellite during emergencies? The typical antennas on modern cell phones are built for cell networks, in which towers are a moderate distance away. I assume the satellite receivers on the SOS network are thousands of miles away from the earth…do iPhones now contain satellite transmitters? How is the battery affected by transmitting to a satellite? Which frequencies are these SOS messages using?
Thanks!
In: 11
Yes, the new models have satellite radios, which is why this new feature is only on the 14. But it obviously isn’t as strong as a satellite phone, so you have to be out in the open and point it at a satellite (it tells you where to face the phone).
To my understanding, the iPhones communicate to the satellites on the L and S bands for satellite communications, so yes, they do have satellite transmitters. Satellite phones/communication devices aren’t particularly new, I believe we started seeing Iridium satellite phones over 20 years ago, and I don’t believe the Apple stuff is any real advancement.
On the horizon there is also a deal announced between Starlink and mobile providers, the next-gen Starlinks will have actual cell radios so it won’t be too much different than just having a slow ground connection (distance is a factor, but there’s also no interference from objects, which is the real signal killer).
iPhone uses 1.6 GHz to transmit and 2.5 GHz to receive satellite messages. Basically the same frequencies that are used in cellular networks. The main trick they use to communicate over long distance is to transmit and receive slowly. In radio communications the slower you transmit the higher signal-to-noise ratio at the receiving end. The higher the signal-to-noise ratio the further you can transmit before the signal becomes indiscernible among the noise. The second difference is that the antennas on the satellites are significantly more sensitive than typical cell tower antennas.
iPhone also uses a directional antenna that improves performance further but that’s not required. They could reduce transmission rate further and still make it work.
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