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Walkie-Textie Wireless Communicator

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Re: Walkie-Textie Wireless Communicator

#121

Post by Catbert59 »

bdjdndb wrote: post #116
Catbert59 wrote: post #44

Earlier quoted context omitted.

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

Blinking a flashlight 1200 times per second is a bit exhausting.

Re: Walkie-Textie Wireless Communicator

#122

Post by RankingMember »

lxgr wrote: post #115
RankingMember wrote: post #105

Earlier quoted context omitted.

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...

I'm fully in favor of that being punishable by catapult worldwide.

Re: Walkie-Textie Wireless Communicator

#123

Post by chrisjj »

nullsmack wrote: post #66
IshKebab wrote: post #37

Earlier quoted context omitted.

Yeah I thought he was going to say it uses T9 too, but it uses an inexplicably archaic chip so there's no way you could fit a dictionary on it.

I'm lowkey shocked it's not a esp32 or something. I haven't seen a ATTINY used for a long time.

ATTINY works as well as the day it was born :)

Re: Walkie-Textie Wireless Communicator

#125

Post by chrisjj »

IshKebab wrote: post #67
addaon wrote: post #52

Earlier quoted context omitted.

They're cheap, robust, readily available, super easy to develop for, have a well-chosen set of peripherals that can reduce BOM even further (e.g. the CCL)… what's not to like?

They have the same price and availability as Cortex M0 chips, are more difficult to develop for (8-bit AVR ouch), and seem to have a similar number of peripherals as any microcontroller. The RP2350 is the same price and several orders of magnitude more capable for example. Really though, how many of these is he making? 3? Cost isn't a factor.

> several orders of magnitude more capable

I'm looking forward to seeing a LoRa texter that's several orders of magnitude more capable /i

Re: Walkie-Textie Wireless Communicator

#126

Post by akvadrako »

throwaway81523 wrote: post #92
lrvick wrote: post #5

If you want something like this with asymmetric encryption, a qwerty keyboard, mesh range extension, and a GUI, try a T-Deck running Meshtastic.

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 worl…

The Lora radios also have a longer-range 325 bits/slower mode called LR-FHSS which does frequency hopping and has 10-60 dB better sensitivity. Though only the sending part is implemented in the low power chips.

Re: Walkie-Textie Wireless Communicator

#127

Post by kingkawn »

tonyarkles wrote: post #21
kingkawn wrote: post #15

Earlier quoted context omitted.

Receipt for LoRa is low power, its transmission that kills the battery

Sort of. Keeping the receiver on and listening 24/7 is going to still use significantly more current than not having the receiver on and putting the microcontroller into a deep sleep mode. The approach in my sibling comment explains how IoT LoRaWAN devices are able to use ~0 current the vast majority of the time and run off, say, a CR2032 battery.

Ok great point if the device is on it will technically use more power than off, true

Re: Walkie-Textie Wireless Communicator

#128

Post by chrisjj »

triyambakam wrote: post #54

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…

> Actually I have/had a lot of these. They can only be used with triple a batteries and don't last long.

You must be mistaking this design for another one. This one was released only a few weeks ago, and specifically offers LiPo batteries:

"The PCB has space for a 2-pin JST socket that will allow you to plug in a standard LiPo battery, such as the ones supplied by Adafruit."

Re: Walkie-Textie Wireless Communicator

#129

Post by Tepix »

IshKebab wrote: post #42
tonyarkles wrote: post #19

Earlier quoted context omitted.

To elaborate on this a little bit, the conventional use isn't peer-to-peer but rather sleepy IoT nodes that periodically wake up to send to a listening base station. The IoT node transmits and then waits a specified amount of time listening for a response back from the base station. The tradeoff is: - The end nodes can spend the vast majority of the time in deep sleep without the radios turned on. - The base station…

There's no reason you couldn't do this in a peer-to-peer system too, especially if you only have a few nodes. Imagine for 2 nodes: 1. Each node transmits a beacon once per second. 2. While they aren't connected, each node listens for sub subset of time (say 10%). 3. Eventually one node will hear the beacon from the other. They can use this to synchronize clocks (the better your clocks the better this works). 4. There…

I don‘t think you‘re allowed to send once per second on LoRa if you play by the rules due to duty cycle restrictions in the license-free ISM bands.

On 868Mhz you get 36 seconds per hour or even 3.6 seconds per hour.

Depending on your power usage sending may also be very slow.

Re: Walkie-Textie Wireless Communicator

#130

Post by clbrmbr »

Tepix wrote: post #129
IshKebab wrote: post #42

Earlier quoted context omitted.

There's no reason you couldn't do this in a peer-to-peer system too, especially if you only have a few nodes. Imagine for 2 nodes: 1. Each node transmits a beacon once per second. 2. While they aren't connected, each node listens for sub subset of time (say 10%). 3. Eventually one node will hear the beacon from the other. They can use this to synchronize clocks (the better your clocks the better this works). 4. There…

I don‘t think you‘re allowed to send once per second on LoRa if you play by the rules due to duty cycle restrictions in the license-free ISM bands. On 868Mhz you get 36 seconds per hour or even 3.6 seconds per hour. Depending on your power usage sending may also be very slow.

Depends on the region. That duty cycle limitation sounds like EU. In USA, there are fewer restrictions on 915MHz, but heavy limits on 434 MHz under part 15. (Subsec 15.235 does not permit pre-determined intervals and 1/sec would definitely not fly!)

Then again, the primary user of 434MHz is actually amateur radio, on which you can operate beacon transmissions if you care to!!

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