4 ms·

I understand that a phone can receive a cellular signal from a satellite. But how can it transmit to a satellite given its limited transmission power (2-3 watts

• Denvercoder9 4y ago
  We have become extremely good at detecting small signals. The extreme example is the DSN, which can still receive a signal from the Voyager probes of 10^-19 W.
  • jacquesm 4y ago
    Slightly different budget for the receiver though. But your average GPS receiver performs similar incredible feats of magic and those are very cheap now.
• twelvechairs 4y ago
  Worth noting these will be low-orbit satellites like StarLink (possibly even lower), which also gets over the latency problem (Starlink Satellites are at ~550km altitude - on the outer edge of the thermosphere, with a return trip latency of ~45ms; Geostationary satellites are 35,786km altitude, with a return trip latency of ~250ms)
• retrac 4y ago
  A few watts on a nice quiet channel will go many dozens of km just with old fashioned FM voice on handheld transceivers. Put a good directional antenna on one end and we're talking over a hundred km. As long as you have line of sight. A few hundred km line-of-sight is fairly unremarkable in itself. Iridium handsets are only like 2 W with compact omnidirectional antennas. Doing this with hardware and protocols not designed for it is pretty cool, though.
• Thlom 4y ago
  A VSAT terminal communicating with a geosynchronous satellite usually only use a 5Watt BUC (10W for higher bandwidth). These are of course mechanically pointed directly to the satellite, but the point being that you don’t need very high transmit power even when the target is 30000+ km up.