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If you want something like this with asymmetric encryption, a qwerty keyboard, mesh range extension, and a GUI, try a T-Deck running Meshtastic.
Isn't there a ban on encrypted amateur signals? Or is this running on a band that allows for it?
See, for instance
> ATtiny814 Why do people still use these ancient chips?
It's next week, so unlikely to happen and I'm not sure what technology I would need to make it all work. Something like Lora plus a way to make the phones work.
There is no resend or reliability in the message sending. If it fails you must retype it. I can't remember exactly if it even indicates it fails? I remember testing with two devices, one in a faraday to test bad conditions.
In the end they got salvaged for parts from my kids for other projects.
The goal was to have a simple backup/emergency communication device and get to learn about LoRa. Not sure which other devices I will try but definitely know more what to look for now.
It's a real shame phones don't have something like this built in. I mean, we literally have satellite communication in every iPhone – or, depending on how you count, every LTE phone, period! Technically, it seems like 90% of what's required is already there anyway, but due to commercial and political pressures, we'll probably never see it happen.
There's a lot of cool radio-related things our smartphones could do but probably never will for regulatory/political/commercial reasons like you note. My pet idea is to make some use of longwave! You know those time signals broadcast around 60 kHz? They cover thousands of kilometres from one transmitter. At 60 kHz the wavelength is 5 kilometres long and the RF tends to diffract around objects like mountains, building…
For example, the German LF time signal, DCF77, dedicates some of its "spare bits" to broadcast civil protection and weather forecast information, the latter of which many simple LCD "home weather station" thermometers can receive and decode.
GNSS (navigation satellite systems like GPS or Galileo) are also an obvious candidate for this, given that essentially all phones already can receive their signals.
It's a real shame phones don't have something like this built in. I mean, we literally have satellite communication in every iPhone – or, depending on how you count, every LTE phone, period! Technically, it seems like 90% of what's required is already there anyway, but due to commercial and political pressures, we'll probably never see it happen.
I wish the hardware was included directly in the phone. It would be super useful for outdoor activities where there's no cell service and you often end up just out of yelling distance.
Earlier quoted context omitted.
There's a lot of cool radio-related things our smartphones could do but probably never will for regulatory/political/commercial reasons like you note. My pet idea is to make some use of longwave! You know those time signals broadcast around 60 kHz? They cover thousands of kilometres from one transmitter. At 60 kHz the wavelength is 5 kilometres long and the RF tends to diffract around objects like mountains, building…
> My pet idea is to make some use of longwave! […] At 60 kHz the wavelength is 5 kilometres long … Dim memory from my Ham Radio days that you’d need an antenna length of 1/4 the wavelength, which wouldn’t be very convenient for portable devices, unfortunately.
Many wristwatches are capable of receiving these LF time beacons, despite usually having antennas more compact than several kilometers.
A question for folks who know things I don't: if I wanted my phones to work in an area without cell signal, for just me and my family, is it possible to build a "personal" cell tower that our phones would just connect to and work, and allow us to text each other? Or is there a whole layer of auth required for our various phones to actually be able to use a fake network?