Long range communication with pi without WiFi access

[Slylos]

Hello all, this is my first post so I hope it’s in the right section. I am currently working on a very ambitious project which uses a Raspberry pi 3 B+ a Pi Hat and 3 raspberry pi’s assembled into a nice little cluster, along with some pi cameras. I have 3D printed a box that will house this cluster and the cameras along with a big battery to power it all attached to a nice solar panel.

I want to place this box somewhere that has no immediate WiFi in the vicinity but I still want to be able to communicate with the pi remotely from a distance of 2-3 miles at most. I was originally going to use an RPI900 and communicate with it using Radio frequency and serial communication. However the RPI900 is a currently defunct product and is relatively outdated.

I was wondering if there was any other good way to communicate with a pi over a fairly long distance without the use of WiFi. Is there any other method of communication or am I stuck with radio frequency? The end goal is to have many of these boxes each housing a cluster and cameras and I want to be able to communicate with the master node (Pi 3 in this case) located in each box. Any suggestions would be appreciated! Thanks for reading this wall of text lol

[mfa298]

I was wondering if there was any other good way to communicate with a pi over a fairly long distance without the use of WiFi. Is there any other method of communication or am I stuck with radio frequency? The end goal is to have many of these boxes each housing a cluster and cameras and I want to be able to communicate with the master node (Pi 3 in this case) located in each box. Any suggestions would be appreciated! Thanks for reading this wall of text lol

I think any realistic method of communication is going to need one of Wires, Light, or Radio Frequency. In terms of a link over a few miles some form of RF is likely the easiest option. (At this overall level WiFi is a form of RF signal).

In terms of RF connections there are a range of options out there ranging from WiFi which will give good speed over short distances to some esoteric things that will give very low data rates over very long distances. The first step is probably to determine what you need that link to do. If it needs to send images from the cameras the solution might look very different from just needing to send some basic command and control.

For simple command and control (and maybe the occasional picture that can take several minutes to transmit) then some ISM RF module might be suitable. There are a range of modules (HopeRF are one common manufacturer) that can connect to the Pi over the SPI interface and send short packets of data. The Lora modules are gaining popularity as they give a decent combination of speed and distance. For most of these modules the speeds will be measured in kbps (or sometimes lower) so are good for basic command and control but any pictures will take a while to send.

For any direct RF link you need a good line of site between the two nodes. This might mean putting your control device up high in a central location.

If you needed a faster link then maybe look at how you can optimise a WiFi network or whether a cellular connection might work (maybe in conjunction with other low speed RF links)