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I am working on a project requiring regular image transmission over a 2km range. This needs to be done in an area with no cellular coverage.

Energy efficiency is a factor, however it does not need to be anywhere near as low as Lora for example (and hopefully a higher bitrate than Lora can achieve).

In an ideal scenario there will be approx 10 nodes (cameras + mcu + power supply) each sending images back to a central device approx 50 times per day.

Some additional details/parameters (as requested in comments):

  1. Approx transmission requirements of 50 * 5MP JPEG photographs per device. E.g. ~50*1.5MB = 75MB per device per day.
  2. Power is to be supplied to each camera by a small solar panel. 10W, 12V (ideally - however this can be varied within reason).
  3. The install location is a farm/rural environment, where most of the cameras will have some obstruction to line of site - e.g. from trees. But it is not fully built up.
  4. The budget is modest, sub $50AUD (~30USD) per device for the comms side of things. Obviously the cheaper the better, but for this project there is a bit of flex.
  5. Regarding frequencies- I am not entirely sure, a method that uses unlicensed spectrum would be strongly preferred.

I will greatly appreciate any suggestions! Many thanks for the assistance to commenters in helping me to better define my query.

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  • \$\begingroup\$ Have you looked into how this is done commercially? \$\endgroup\$
    – Andy aka
    May 26, 2020 at 9:10
  • \$\begingroup\$ How do the cameras receive power? \$\endgroup\$
    – Andy aka
    May 26, 2020 at 9:35
  • \$\begingroup\$ Thanks @Andyaka - The cameras receive power from solar panels, and this can be scaled to suit the power requirements for the transmission. I am yet to find a commercial system that meets this specific case. Some related alternatives are: 1) Long Range video surveilance systems - these seem to only work up to a few 100m and provide a significantly higher bandwidth than my usecase or 2)Systems that use 3G or 4G connections for uplin (sadly not availble at this location).. \$\endgroup\$
    – R. Fitz
    May 26, 2020 at 11:11
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    \$\begingroup\$ This is not necessarily a need which has a general solution, and not clear that it is question which is on topic here, as so much hinges on the off-topic question of regulations. The terrain and buildings you have to work with may be key - for example if you can get the receiver up on a hill, windmill, or whatever where you could actually see all of the nodes. It's possible you might be able to rig up some sort of repeating scheme with the ESP32 camera modules running in a below-wifi-protocol kind of way, and add extra solar fill-in nodes to complete the more difficult paths back. \$\endgroup\$
    – Chris Stratton
    May 26, 2020 at 13:49
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    \$\begingroup\$ I would encourage you to think about how much energy you can actually rely on using solar panels in varying weather. Does you system need to work at night or on cloudy days? Also, you need to make sure that the kind of radio system you are talking about is legal in your locality. To get reliable 2km range you may interfere with other devices 5km or 10km away. \$\endgroup\$
    – Elliot Alderson
    May 26, 2020 at 19:41

1 Answer 1

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Maybe some 900 Mhz modules if that is allowed.
The receiver needs at least 70 kb/s of bitrate if there is only one channel.
Lora has 5 kb/s, at the low range mode.

Based on your specs I'd wait around for Starlink and see that's going to cost you. Current Iridium is not very affordable.

I think the only license free option for these data-rates is WiFi, if DFS regulations can be followed. You can get sub $50 long range wifi gear from mikrotik. You'd need to beef up your battery design, since they will need some power. And you probably need a dish.

The other option is to setup you own WISP with cellular modems. But you'd need licensing for that, if possible at all.

Maybe something lower power is possible if you are able to make a mesh network where you can scatter a few extra repeater nodes around.

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  • \$\begingroup\$ thanks very much for your detailed response - It is greatly appreciated. \$\endgroup\$
    – R. Fitz
    May 27, 2020 at 23:39

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