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Existing smartphones will connect with new satellite constellations in 2023

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Re: Existing smartphones will connect with new satellite constellations in 2023

#11

Post by Denvercoder9 »

cft wrote: post #5

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 max)? Edit: googling my own question https://arstechnica.com/science/2021/09/a-virginia-company-h...

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.

Re: Existing smartphones will connect with new satellite constellations in 2023

#13

Post by jrexilius »

This sounds to me like a single, global, commercial IMSI catcher that can track international movement of cell phones.. I guess the question is how good their triangulation will be, but I imagine the back-end data market for this will be fairly lucrative for them. And they don't really need any countries permission to _listen_ from space... .. .

Re: Existing smartphones will connect with new satellite constellations in 2023

#14

Post by twelvechairs »

cft wrote: post #5

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 max)? Edit: googling my own question https://arstechnica.com/science/2021/09/a-virginia-company-h...

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)

Re: Existing smartphones will connect with new satellite constellations in 2023

#15

Post by jojobas »

RC_ITR wrote: post #2

Just as a PSA in case not everyone knows this new feature. In the US and a growing number of other countries, the latest iPhones have a satellite network for emergencies. If tech giants are going to spend money on something cool, might as well use it. https://support.apple.com/en-us/HT213426

It's not exactly "satellite network", it's piggy-backing on an existing SAR reception infrastructure that used to require somewhat expensive dedicated devices. Not sure it's a good idea, I'd expect a wave of SAR requests for not real emergencies.

Re: Existing smartphones will connect with new satellite constellations in 2023

#17

Post by jacquesm »

Denvercoder9 wrote: post #11
cft wrote: post #5

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 max)? Edit: googling my own question https://arstechnica.com/science/2021/09/a-virginia-company-h...

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.

Slightly different budget for the receiver though. But your average GPS receiver performs similar incredible feats of magic and those are very cheap now.

Re: Existing smartphones will connect with new satellite constellations in 2023

#18

Post by modeless »

rootusrootus wrote: post #10

So there's Bluewalker 3 which uses a big antenna to achieve communications with unmodified cell phones, and then Elon claiming that regular Starlink satellites will be able to do the same thing without that ginormous antenna. How does that work? Both are at roughly similar altitudes, BW3 just slightly higher.

It's not "regular" Starlink satellites. They are going to launch new ones that do have a big antenna for this service. It's not as big as BlueWalker 3, and as a result the service is not as good. But it will work for texting and maybe voice calls.

Re: Existing smartphones will connect with new satellite constellations in 2023

#19

Post by retrac »

cft wrote: post #5

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 max)? Edit: googling my own question https://arstechnica.com/science/2021/09/a-virginia-company-h...

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.

Re: Existing smartphones will connect with new satellite constellations in 2023

#20

Post by tpmx »

moritzwarhier wrote: post #9
copperx wrote: post #4

I'm just glad because that's going to end the longstanding misconception that phones are connected to satellites. They will finally be.

I have never heard of this misconception, but fixing the notoriously unreliable mobile coverage by turning existing phones into "satellite (internet!) phones" sounds wild

The much more common misconception is that internet traffic between continents is carried via satellites.
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