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Walkie-Textie Wireless Communicator

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Re: Walkie-Textie Wireless Communicator

#21

Post by tonyarkles »

kingkawn wrote: post #15
clbrmbr wrote: post #8

Earlier quoted context omitted.

LoRa is actually pretty thirsty on receive. You’d need some scheme for synchronization if you want to reduce power consumption.

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.

Re: Walkie-Textie Wireless Communicator

#22

Post by 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.

Re: Walkie-Textie Wireless Communicator

#23

Post by patwolf »

threemux wrote: post #10
patwolf wrote: post #4

For anyone looking for an off-the-shelf solution for wireless texting, I've used the BTECH GMRS-PRO. You can send messages on the device, but it's much easier to connect it to your phone via BLE and text through the app. However, it uses GMRS bands, not LoRA, so all the FCC restrictions apply.

While I highly doubt you'd ever get in trouble, data transmissions on GMRS are severely restricted by the FCC. You obviously need the license (though it's just a fee and covers your whole family). In any case, I'm pretty sure this device is illegal to use for short text messages. It doesn't appear to comply with several of the restrictions on digital emissions in 47 CFR 95.1787(a), namely it appears to have a removab…

The antennas on mine don't appear to come off, at least not easily. I read somewhere that they came off on the early models but are now glued.

It does enforce time limits. If I send a message or something that uses digital communication (like gps coordinates), it won't let me send another one immediately after.

Re: Walkie-Textie Wireless Communicator

#25

Post by bityard »

sejje wrote: post #7
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?

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

Baofeng does make GRMS- and FRS-specific radios that comply with FCC regulations.

Re: Walkie-Textie Wireless Communicator

#26

Post by threemux »

jpalawaga wrote: post #13
threemux wrote: post #10

Earlier quoted context omitted.

While I highly doubt you'd ever get in trouble, data transmissions on GMRS are severely restricted by the FCC. You obviously need the license (though it's just a fee and covers your whole family). In any case, I'm pretty sure this device is illegal to use for short text messages. It doesn't appear to comply with several of the restrictions on digital emissions in 47 CFR 95.1787(a), namely it appears to have a removab…

Why wouldn’t they comply with tx duration? You don’t want excessively long tx as you can’t rx at the same time. You’ll lose messages.

There is no amount of time that guarantees you won't interfere with another user on a shared channel without time division. Any protocol used has to account for it no matter what.

But discussion of that is irrelevant because the regulation is no more than one every 30 seconds and each one can't be longer than 1 second in duration. This necessarily limits the length of messages you can send or requires more efficient modulation and/or weaker error correction at the tradeoff of worse weak-signal performance.

Re: Walkie-Textie Wireless Communicator

#27

Post by numpad0 »

gausswho wrote: post #17
Xmd5a wrote: post #9

Earlier quoted context omitted.

The distinctive element here is the hardware. Briar allows you to sync via local wifi and bluetooth (i.e. the range is tiny) but since it's a mesh network your message will be relayed eventually. This device though doesn't seem to support mesh connectivity because it doesn't have this short range limitation in the first place. It uses a LoRa chip with a range of a few kilometers. The bandwidth is tiny though, for rea…

Does the duty cycle mean it's only sending a receiving for those 36 seconds of every hour? The hermit in me is enthused by communicating with this restriction.

IANAL/IIUC, it can also be, e.g., 10ms every 1000ms, and it only applies to emission side of it. You don't have to actually put away the device for an hour after picking up once if the modem is not sending 36 seconds straight. But it does divide the data rate by 100.

Re: Walkie-Textie Wireless Communicator

#28

Post by threemux »

patwolf wrote: post #23
threemux wrote: post #10

Earlier quoted context omitted.

While I highly doubt you'd ever get in trouble, data transmissions on GMRS are severely restricted by the FCC. You obviously need the license (though it's just a fee and covers your whole family). In any case, I'm pretty sure this device is illegal to use for short text messages. It doesn't appear to comply with several of the restrictions on digital emissions in 47 CFR 95.1787(a), namely it appears to have a removab…

The antennas on mine don't appear to come off, at least not easily. I read somewhere that they came off on the early models but are now glued. It does enforce time limits. If I send a message or something that uses digital communication (like gps coordinates), it won't let me send another one immediately after.

Wow I'm surprised - I based my message of the manual on their site which pretty clearly shows a detachable antenna and says nothing about time limits. I wonder if they received something from the FCC saying they can't market a GMRS radio that isn't type-accepted.

Re: Walkie-Textie Wireless Communicator

#30

Post by wildzzz »

kingkawn wrote: post #14
sejje wrote: post #7

Earlier quoted context omitted.

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

Not true, GMRS licenses are much easier to get

While true, it's important to remember that not all ham radios that can transmit on GMRS bands are legal to do so. GMRS and FRS don't have the same "anything goes" allowances that ham operators have. Radios for these bands must be purpose built for these bands. Of course no one is going to know your compliant GMRS/FRS transmissions are coming from part 97 radio. Although most quality ham radios don't allow transmission on anything but the ham bands. The increased FCC enforcement of these Chinese radios means that many now have extra filters to reduce spurious emissions outside the ham bands, meaning they shouldn't work as well on GMRS and FRS.

If you want to use GMRS, buy a GMRS radio.

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