Ask HN: DIY Satellite Phone

[the-last-user]

I'm a ~30y.o. physics researcher and my family is at the moment living on their skin the Ukrainian crisis. Up until now they have been able to get (bad) internet access however, after the latest news I fear that Russia will soon disrupt network communications.

Unfortunately I haven't been smart enough to foresee this situation and I didn't provide them in time with any satellite phone/starlink/similar.

I'm in search of any do-it-yourself device capable of connecting to satellite and send SMS or make phone calls. My father has some electronics skills and is fairly good at programming.

My hope is that, perhaps, someone could guide me to a good tutorial on how to build a communication device so that I could still hear from them in case the internet will go down.

[runjake]

Edit: I've decided you should not do this -- there are way too many OPSEC concerns, but I'll leave my original comment, for posterity.

APRS[1] might fit the bill.

You could potentially acquire the hardware to do it and/or use a web interface/download a mobile app such as https://aprs.fi .

Using an Internet service like APRS, you could send location data (make sure you're practicing proper opsec) along with messaging, just pick an unused callsign (though you'll be violating EULAs).

Radio-wise I see a few nodes up in various areas of Ukraine, but none in Kyiv at the moment.

As long as they could periodically get signal. They could send short coded status updates (eg. 7 == good, 11 == send help, 8 == send supplies).

You technically need a ham license to operate the radio equipment.

1. https://en.wikipedia.org/wiki/Automatic_Packet_Reporting_Sys...

[leastonce]

Aprs messages sent to SMSGTE can be routed as SMS messages …

[leoedin]

Unfortunately satellite phones are such niche devices that there's not really any way to do it except by buying a commercial device. Even a "DIY" device would in reality be a series of commercial off the shelf modules - unless you had those to hand then you'd need to get them delivered, which means you might as well buy a commercial satellite phone.

If for some reason you could buy the bits, you could probably piece together a communicator with a satellite modem module (https://uk.rs-online.com/web/p/rf-modules/2131335) and a microcontroller or single board computer. It seems pointless to bother though - why not just buy a Garmin or Spot for the same price.

You could replace the modem part with a software defined radio (SDR) - that's generic enough there's a distant possibility you'd find one locally in an LTE base station or some other commercial radio device. However, the software effort to implement the satellite modem protocols would be immense - basically impossible.

Satellite phones are also so niche that they'd draw a lot of attention to the user - something you probably don't want if you're in a combat zone.

A better bet would be to make use of the equipment you probably do have - cell phones, wifi access points, ethernet cables - to extend the reach of places which do have internet. That would require there to be connectivity somewhere, which you could then expand out using point to point wifi networks. You could make a long range WiFi antenna using a parabolic satellite dish and a USB wifi adapter or wifi router. If you can find cellular connection on a rooftop you could bridge it to the ground via a couple of wifi access points and a long ethernet cable.

There's also apps - eg https://briarproject.org/ - which allow for message passing over local WiFi or Bluetooth networks. Realistically there's no magic bullet though.

[bitxbitxbitcoin]

You should look into HAM radio.[0]

[0] https://hamradioprep.com/ham-radio-satellites/

[ianburrell]

Ukraine has shut down amateur radio. It is illegal for operators in other countries to talk to country that has banned ham radio.

This frees up frequencies for military use. It is also dangerous to be transmitting in war zone; ham radio is pretty obvious.

[leastonce]

https://www.wired.com/2009/04/fleetcom/

Not legal but this is pretty trivial to do … a few bits of wire and a very cheap Chinese radio.

Other options are ham radio … hopefully the ham community will help with message relays.

Although from a safety perspective it’s trivial to triangulate transmissions and they could be come a target for attack.

Anyone transmitting, using satellite phones or starlink type devices should be aware of the additional risks.

[rrrodia]

I'm aware that this is not what you are looking for probably, but on Hackaday there are multiple lorawan projects like this; https://hackaday.io/project/183966-off-grid-lora-communicato... Though this is only for local communication, and i doubt you can get the parts in this time.

Most (if not all) satellite phones work with a subscription as far as im aware. I will try to research further.

[Robotbeat]

There is a company called Lynk Global (was Ubiquitilink) that has 5 satellites in LEO that allow SMS text messages to be sent to and received from unmodified cellphones on the ground. Also capable of LTE voice and data, but less common.

Lockheed Martin has a similar capability.

[willcipriano]

I've got this for backpacking: https://www.amazon.com/Garmin-GPSMAP-Handheld-Satellite-Comm...

It allows for text messages via satallite and the service is fairly affordable.

[ianburrell]

The best option is probably satellite messenger. They are a lot cheaper than satellite phones and only allow sending and receiving messages including locations. The two options are Garmin inReach and Spot.

[obayesshelton]

Great question and could be a fun project.

What is stopping a group of developers making a sat phone using a third-party satellite service. I am pretty sure AWS has ground base or something....