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Walkie-Textie Wireless Communicator

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Re: Walkie-Textie Wireless Communicator

#111

Post by sidewndr46 »

implements wrote: post #50
retrac wrote: post #38

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.

The 1/4 wavelength is derived from the half-wave dipole. It's not necessary to have an antenna that is 1/4 wavelength. It'll probably perform better if it is closer to that size, but it isn't required.

Re: Walkie-Textie Wireless Communicator

#112

Post by sidewndr46 »

pastorhudson wrote: post #11
etrautmann wrote: post #6

Earlier quoted context omitted.

Can you elaborate on the restrictions? Is it just that the Baofeng allows you to transmit on some frequencies that aren’t legal or at power levels that aren’t allowed or is it not allowed in the US at all?

To use GMRS you need a license to be compliant with fcc. It’s not expensive I think $60 for 10 years and it covers your family. You can then use GMRS. GMRS is all the same FRS channels plus several more. GMRS can also transmit at up to 50mw on some of the non-FRS channels. To be using GMRS in compliance you have to use an FCC Part 95E certified device. These Baofeng / Btech devices are usually not GMRS certified. So…

I think you said "50mw" when you meant "50 watt"

Re: Walkie-Textie Wireless Communicator

#113

Post by sidewndr46 »

tejtm wrote: post #77
sejje wrote: post #7

Earlier quoted context omitted.

You need a ham license to do most anything with a Baofeng legally.

No licence is required to listen to any frequency.

Not event remotely true in the US. Reception of cellular radiotelephone signals is prohibited by law unless you are a participant in the conversation.

Re: Walkie-Textie Wireless Communicator

#115

Post by lxgr »

RankingMember wrote: post #105
password4321 wrote: post #47

Earlier quoted context omitted.

I would settle for push-to-talk over WiFi on my phone interoperable with dedicated devices with no monthly fees.

Not that I don't agree that push-to-talk is a cool tool, but good lord was it a scourge in public environments. People shouting into their phones, then the Nextel "boop-boop" followed by a loud static-y response while you sit on the bus wishing for an asteroid.

I'll take it over people blasting reels without headphones on public transport...

Re: Walkie-Textie Wireless Communicator

#116

Post by bdjdndb »

Catbert59 wrote: post #44
magnat wrote: post #34

> 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.

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.

If you have line of sight, a simple flashlight would work for communication

A robust communication needs to work in valleys

Re: Walkie-Textie Wireless Communicator

#117

Post by LelouBil »

I was trying to do something similar with esp32+lora development boards.

And I got like 3km range in my city so it was great !

But then I wanted to make it a ""usable"" thing and started getting stuck on designing a protocol that allows multiple senders at the "same time".

I thought of doing a time slice system since this whole project was inspired by a telecommunications class I had, but the issue would be that people you would need to know in advance the number of slices and your assigned one and also the devices would have to be synchronized, and I really wanted to make it dynamic, do anyone can just turn on their thing and it does a sort of handshake until everything works.

If anyone has pointers It'd be very appreciated, I found out about meshtastic.org while doing this project too.

In the end this was my first embedded experience, and my first embedded with Rust, so at least I got something "working" but I would love to make something as "usable" as this post.

Re: Walkie-Textie Wireless Communicator

#118

Post by lrvick »

windexh8er wrote: post #103
subscribed wrote: post #95

Earlier quoted context omitted.

Amateur, yes, but this is not amateur radio. This is unlicenced.

The Meshtastic firmware actually has an 'Is Licensed' [0] checkbox if you want to operate with both the privileges and restrictions of operating under that license. The major upside is transmit power and the downside is not being able to use encryption. [0] https://meshtastic.org/docs/configuration/radio/user/#is-lic...

I would also note that I have never once heard of enforcement on using encryption but we -have- seen enforcement of using too much transmit power without a license.

So if you like, get a license, crank transmit power, then use encryption all you want and don't worry about it.

It will be enforced about as fast as movie torrenting.

Re: Walkie-Textie Wireless Communicator

#120

Post by Infernal »

Xmd5a wrote: post #106
Infernal wrote: post #48

Earlier quoted context omitted.

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

>802.11ah, or Wifi HaLOW Thanks a lot I wasn't aware of this technology. Turns out you can already buy gateways and boards/modules, and it seems it wasn't the case last year. Any tip on how I can power these things wirelessly ?

I have seen low power meshtastic devices serving things like BBSes on solar power, I’m not familiar enough with 802.11ah devices to know if solar would be feasible.
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