Re: Recent Experience With RF "Modem-ish" Data Links ?

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From	TheLastSysop <thelastsysop@dev.null>
Newsgroups	comp.os.linux.misc
Subject	Re: Recent Experience With RF "Modem-ish" Data Links ?
Date	Tue, 26 May 2026 22:11:11 GMT
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> About 1000 meters.
> NO power utilities there.
> Am interested in 'weather/environ' info and
> maybe still frames from a low-rez THERMAL
> camera. A 'live mic' might be interesting
> even at rather low bandwidth.

For 1 km and a small solar/battery box, split the requirements first.
Weather/environment telemetry is easy. Still frames are possible but slow. A
live microphone is the thing most likely to push you out of the cheap low-power
radio class.

LoRa is a good fit for small packets: sensor readings, battery voltage, status,
alarms, maybe a tiny thumbnail if you are patient. Do not expect it to behave
like slow WiFi. Depending on spreading factor and legal duty cycle limits, a few
kbit/s or less is a more realistic planning number than the headline figures.

The current cheap modules worth looking at are usually UART/SPI LoRa boards
based on Semtech SX127x/SX126x parts. Ebyte E32/E22/E220 style UART modules are
common if you want "serial cable replacement" behavior. Digi XBee/XBee-PRO
900HP, RFD900x, Microhard, FreeWave, etc. are more expensive but more finished
products. Check the band and power limits for your country; 433/868/915 MHz
modules are not interchangeable legally.

A few practical points:

* Use a real outdoor antenna, placed high and dry, before throwing power at the
problem. Fresnel clearance matters even at only 1 km. * Use packets with
sequence numbers and CRCs, not a bare byte stream, even if the radio sells
itself as transparent serial. * If you need multi-drop, handle
addressing/retries in your protocol. "Radio RS-485" boxes often only make a
transparent half-duplex serial link; collision behavior can be ugly. * For
battery life, let the remote node sleep and wake on a schedule. A Pi can work,
but a small MCU plus radio will be much easier to power and hide. * Send
summaries often and images rarely. A tiny thermal frame may be acceptable every
few minutes; audio probably wants a different link.

If you have line of sight, a pair of small directional 2.4/5 GHz outdoor CPE
units can do 1 km easily, but they draw watts continuously and are more visible.
For disguised, low-duty-cycle environmental telemetry, LoRa or a sub-GHz serial
modem is the more natural starting point.

-- 
TheLastSysop <thelastsysop@dev.null>
"I survived the great rm -rf / rehearsal and all I got was this .signature."

Thread

Recent Experience With RF "Modem-ish" Data Links ? c186282 <c186282@nnada.net> - 2026-05-25 01:46 -0400
  Re: Recent Experience With RF "Modem-ish" Data Links ? rbowman <bowman@montana.com> - 2026-05-25 17:56 +0000
    Re: Recent Experience With RF "Modem-ish" Data Links ? c186282 <c186282@nnada.net> - 2026-05-26 01:27 -0400
      Re: Recent Experience With RF "Modem-ish" Data Links ? TheLastSysop <thelastsysop@dev.null> - 2026-05-26 22:11 +0000
        Re: Recent Experience With RF "Modem-ish" Data Links ? c186282 <c186282@nnada.net> - 2026-05-26 23:04 -0400
          Re: Recent Experience With RF "Modem-ish" Data Links ? rbowman <bowman@montana.com> - 2026-05-27 03:21 +0000
            Re: Recent Experience With RF "Modem-ish" Data Links ? c186282 <c186282@nnada.net> - 2026-05-27 00:18 -0400
              Re: Recent Experience With RF "Modem-ish" Data Links ? rbowman <bowman@montana.com> - 2026-05-27 07:09 +0000
            Re: Recent Experience With RF "Modem-ish" Data Links ? The Natural Philosopher <tnp@invalid.invalid> - 2026-05-27 14:14 +0100
      WiFi range ... Lars Poulsen <lars@beagle-ears.com> - 2026-05-31 21:19 -0700
        Re: WiFi range ... TheLastSysop <thelastsysop@dev.null> - 2026-06-01 04:26 +0000
          Re: WiFi range ... Lars Poulsen <lars@beagle-ears.com> - 2026-06-01 22:44 -0700
      Re: Recent Experience With RF "Modem-ish" Data Links ? Andy Burns <usenet@andyburns.uk> - 2026-06-01 08:10 +0100
        Re: Recent Experience With RF "Modem-ish" Data Links ? TheLastSysop <thelastsysop@dev.null> - 2026-06-01 07:33 +0000
          Re: Recent Experience With RF "Modem-ish" Data Links ? c186282 <c186282@nnada.net> - 2026-06-02 01:35 -0400
        Re: Recent Experience With RF "Modem-ish" Data Links ? c186282 <c186282@nnada.net> - 2026-06-02 01:15 -0400
          Re: Recent Experience With RF "Modem-ish" Data Links ? Lars Poulsen <lars@beagle-ears.com> - 2026-06-01 22:50 -0700
            Re: Recent Experience With RF "Modem-ish" Data Links ? c186282 <c186282@nnada.net> - 2026-06-02 03:04 -0400

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