I know more about the mobile internet side of things - not exactly stuff like cameras only etc.
Do you have enough signal at the farm to run cheaper devices and antennas?
Do you want to pay for multiple cell plans or would it make sense to have one command/central and increase/mesh the WiFi output?
LTE modems are cheaper - so I’d exclude 5g if your use case doesn’t require it.
At this point, I've found a carrier that does 10GB for $17 a SIM (and I could probably get away with less data for cheaper), and I'd be fine with that. I have several rPis that act as hubs taking in LoRa data from things like solar pumps, water bowls and bins, but backhauling to the central server over LoRa is a pain, and we don't have LoS to all of them so using radio bridges is spotty. Some sites are 10km away over hills. And moving everything to MQTT would make my life easier than my custom BS programming that has devices talking to each other directly.
We don't generally have issues with phones and where I do, I can probably put up an antenna if the dongle has an external port, or I'm willing to spend extra $$ for an uplink with external. I currently have a Microhard LTE-CAT4 that I use on one remote site that seems to get good reception, but that unit is pretty pricy and I have to fart around with network cables and power when I could just be plugging in a USB dongle.
I see a lot of cheap ones on Amazon, but I was hoping someone had a common Linux specific model they know works, because most of those look pretty janky.
MC7455 - https://a.aliexpress.com/_mMEGTFw
Random Enclosure - https://a.aliexpress.com/_m0pHSD2
I’m picking an older LTE only chip that I’m familiar with and a compatible enclosure. There might be cheaper.
It’s far from plug and play as you’ll either need to come up to speed with AT command or research if some libraries interact it. Edit: I’d look at what OpenWRT is using - I’ve plugged these into those and had a relatively plug and play experience.
Entirely possible this isn’t what you’re looking for - what’s a link to one of these dongles on Amazon?
Ah , interesting - hadn’t seen them like that before – but the premise looks the same to what I was suggesting.
In the video on the product you can see them mucking with AT commands. OpenWRT seems to be using https://openwrt.org/docs/guide-user/network/wan/wwan/modemmanager so I think you’d just want to confirm the chips on those dongles have had success with ModemManager - and then be running ModemManager from your Pis.
I'm using an old "ZTE Falcon" hotspot, I got it from T-Mobile maybe 8 years ago, it's 4G/LTE, still works fine, tried multiple SIM (mine is unlocked), in general I'm using it via WiFi because we connect multiple phones/tv/laptops on it while traveling in a RV. I tested it with a USB cable between my linux and the hotspot, and it appears in Linux as a "usb0" interface, got an IP address, and works fine, it disables WiFi IIRC when plugged by USB.
$20 on eBay free shipping https://www.ebay.com/p/2255550619
My carrier is Google Fi
one perk is that they will give you free data-only sims (up to 10 I think?) and you just pay for the data you use like any other data. I have used old Android phones in USB tether mode this way, and it works just fine. So, rpi+old/cheap phone should do the trick.
One fun bonus is that if you tether over USB it will work as a WiFi dongle, too
the failover from WiFi to cell should happen on the phone, transparently iirc. Not sure if that affects you.
Caveat is that I did this a while ago, and their pricing structure may have changed. Finished to be a great deal but has slowly become another carrier with not much to differentiate it...
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