Walkie-Textie Wireless Communicator
92 comments
·August 16, 2025magnat
Catbert59
I've tested LoRa from Hill<->Hill and Flat Land<->Flat Land and 30-60km worked with plenty of SNR left.
On 868MHz with standard 5dBi omnis.
Thesis: as long you are using one of the more robust LoRa settings it always will work as long you have LoS or at least only lightly obstructed LoS.
junon
What's the data transmission rate with the balloon, put of curiosity?
magnat
Hard limit is 3.5kbps with 148dB link budget (Medium Fast preset in Meshtastic [1]). In practice - a packet worth of hundred bytes every half a second or so.
junon
Is that the cap of the whole system or can multiple users use it with individual caps of 3.5kbps? That's somehow both faster and slower than I expected.
kube-system
Reminds me of what the messenger on the Cybiko was trying to be. Too bad LoRa wasn't a thing back then, it would have been more useful if it had a better range.
ljf
I remember seeing these on some tech show here in the UK - and being in love with the idea - seemed so cool and 'archivable' for a young person to own. A few years later they were dirt cheap on ebay - new/boxed, but by then the itch had gone, but I wish now I'd bought one.
shooker435
Whoa, I wonder if I still have my Cybiko Xtreme somewhere.
triyambakam
Actually I have/had a lot of these. They can only be used with triple a batteries and don't last long. The usb c is only for development (and still lacks power so you still need batteries). The typing as maybe expected gets tiring. I tried using different compression ideas to save characters.
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.
lrvick
If you want something like this with asymmetric encryption, a qwerty keyboard, mesh range extension, and a GUI, try a T-Deck running Meshtastic.
throwaway81523
Lora data rate is still maybe 100x or 1000x higher than I'd want. I'd like something just fast enough for text chat, let's say 10 bps (maybe 3 chars/sec with some data compression), and a fallback slower rate for messaging, like 1 bps or slower (2 minutes for a 50 char messsage). That would give another 20 or 30 db of coding gain for much better range. There could even be a .01bps mode. Finally, put it on HF for worldwide range ;).
This is all deployed by hams down to around 1 cps, by the way (js8call.com).
geokon
there is also the LILYGO T-LoRa Pager
https://www.cnx-software.com/2025/08/12/lilygo-t-lora-pager-...
junon
Isn't there a ban on encrypted amateur signals? Or is this running on a band that allows for it?
Infernal
Yes and yes. In the US, 900-930MHz (nominally the 915MHz band) is available for use with no license required so encryption is fine (similar to your 2.4GHz or 5GHz wifi access point).
People interested in LoRa may also be interested in 802.11ah, or Wifi HaLOW
ninalanyon
LoRa is surely mostly for machine to machine, Internet Of Things. There are lots of web pages that take it for granted that encrypted communications are not merely allowed but expected.
See, for instance
natas
yes!!!
kingkawn
Or get a rak device that has a better antenna and range than the T deck
hackcasual
Oooh, which one has a keyboard?
lrvick
t-deck has a keyboard and is ideal for a personal handset.
A G2 Basestation or rak device is ideal for node to node communication to act as a base station for range extension.
jvm___
I'm backwoods camping next week, and we have 25 people spread out over three sites. I was thinking it would be funny to bring some old rotary dial phones and some sort of way of hooking them up, and then just have that as the intercom between sites for when dinner is ready or whatever.
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.
opan
Chaining together a few WiFi routers and running a local IRC server with ergo could work well (so get everyone on the same WLAN even if no Internet). There is also Briar chat on mobile. Maybe Mumble for voice could work. I'd look for routers on Craigslist or eBay that are under $20 each and have OpenWrt support. Have had good luck with the Netgear R6220 in the past, but there could be other good options as well.
slug
Cheap FRS walkie-talkies, can find plenty of these on ebay if don't want to buy new (will need new batteries though).
ixwt
DeviantOllam has a few videos on YouTube about some con/meetup thing he goes to that does just this. You might be able to get a few ideas from that.
jonbiggums22
A couple years ago I stayed at an AirBnB and there was an old rotary phone in the kitchen. Unfortunately, I found it was merely placed there as an antique curio and wasn't hitched up with service. I felt a little cheated honestly.
IOT_Apprentice
They did that on the last episode of Star Trek Strange New Worlds (rotary phones).
lxgr
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.
retrac
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, buildings, etc. that get in the way. Longwave tends to penetrate underground, and through Faraday cages meant for short wavelengths.
Those time signals broadcast, in effect, 1 bit per second. The receiver is dead simple electronically and requires almost no energy to run. What if we broadcast a more modern error-corrected data stream? Every device could be supplied with a receive-only stream of a few hundred bits a second of whatever. I admit it's a solution somewhat in search of a problem. Weather updates? Emergency alerts?
lxgr
Some countries already do this!
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.
tatjam
Galileo already has search and rescue (SAR) and emergency functions (EWSS)! GPS is trickier, as it's still sort of a millitary-first platform.
implements
> 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.
lxgr
Only for most efficient transmission. Reception just scales with antenna size, so as long as your transmitter is powerful enough in terms of effectively radiated power, you can make the receiver arbitrarily small.
Many wristwatches are capable of receiving these LF time beacons, despite usually having antennas more compact than several kilometers.
f1shy
Actually some have. At least I know that in Peru, operators were forced to offer such a thing in case of earthquake. I do now have details though, maybe was not simple as I was told.
RandallBrown
There's an app called Rattlegram that will convert data into audio that you can then send over a walkie talkie.
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.
password4321
I would settle for push-to-talk over WiFi on my phone interoperable with dedicated devices with no monthly fees.
krunck
Very nice. I'd like to see one like this that uses frequencies that can pass through 200m of rock. Obviously the radio frequency will need to be much, much lower (https://en.wikipedia.org/wiki/Through-the-earth_communicatio...). Why, you ask? Cave rescue situations.
teleforce
It's not only lower frequency, it also need robust wireless modulation that can work with very limited LoS where LoRa perform badly. LoRa is pretty much useless in your use cases.
Currently we're working on a new wireless modulation that has much higher bandwidth (similar to HaLow) but 1000x better in BER performance than LoRa in limited LoS propagation model based on simulation. If we can get 100x improvement in real world testing for the high bandwidth version I'm more than happy. Our Japanese collaborators has tested the lower bandwidth version similar to LoRa bandwidth and frequency, and it work fine inside a bunker.
If you're interested perhaps we can collaborate on testing the solution. Already proposed to IEEE as new wireless PHY modulation but to no avail yet.
joshmarinacci
If you are using the lilygo tdeck, I’m working on Rust support here.
bluGill
While people did get really fast at typing on those num keypads, there was a lot of RSI injuries among people who did it often. a number key bad might be the best compromise despite that, but don't lose sight of just how bad they were and take effort to avoid the issues.
null
pavel_lishin
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?
f1shy
Yes. There is a way to setup a private cell using SDR. There was a talk about that in Chaos Computer Club some years ago. I do not remember how they did with the simcards, if they were custom, or normal out of service ones. Caution: because the spectrum band is licensed, it will be automatically illegal pretty much everywhere!
Here a quick search: https://www.reddit.com/r/sdr/comments/1bn1n5f/how_to_run_ope...
jonbiggums22
Isn't this what Wifi Calling is for?
jeroenhd
VoWiFi requires an internet connection. It dials back to your carrier.
Nothing preventing you from configuring a local SIP server or doing IP-to-IP calls, though. I think every platorm imaginable has some kind of free SIP client.
joshmarinacci
Not really. This stuff is heavily NDA and patent encumbered. You’d be better off setting up a local wifi network and using an IP based audio call system.
seidleroni
I'm not sure if this applies to all carriers but with many carriers if you are on wifi you can send/receive text messages and sometimes even make calls. Certainly you could use WhatsApp or similar in that case.
mikestew
...with many carriers if you are on wifi you can send/receive text messages...
How would you propose that those messages get routed if there is no connection to either the internet nor a cell provider?
pavel_lishin
Not if I'm in the middle of the woods with no connection to the outside world.
aspenmayer
Here’s a recent post I found on open source software for that. I remember a recent post about folks using base stations that were popular with the Helium network to run their own stuff, but I can’t find it at the moment.
LastTrain
I've tried and tried to use LoRA devices w/ meshtastic for various things, and can't get them to communicate reliably. Even with two devices sitting next to each other. Not even working reliably enough to be used as a toy. What am I doing wrong?
> LoRa can reach a range of up to 3 miles (4.8 km) in urban areas, and up to 10 miles (16 km) in rural areas
In mountainous area LoRa on 868MHz band reaches over 100km. Last month we had a stratospheric balloon with a Meshtastic node attached. It established direct (albeit intermittent) connection between Warsaw and Berlin.