I tried to make an open source radio system like LoRa before LoRa existed, but I mostly failed to deliver on my kickstarter. :-/
I did make a 915/868 MHz frequency hopping radio protocol that is open source, as well as ARM powered hardware to drive it, but it turns out everything I wanted to do was way more work than I realized.
Bummer that LoRa hardware is proprietary, but I suppose so was the cpu and radio chip I used. Would be nice to get some open source digital radio chips!
I have lots of hardware I could share if anyone would pick it up in the Bay Area, and I can make all the IP CC0 or MIT licensed instead of copyleft it desired.
Does a single company own/control all the towers?
There are currently over 8000 of these gateways worldwide (see also the map on https://www.thethingsnetwork.org/map).
The distances are of course much lower if there are obstacles (like concrete buildings) between the transmitter and receiver.
Could you use a general purpose sdr like an HackRF as a base station?
Alternatively two LoRa radios can just talk point-to-point between each other.
"Alternatively two LoRa radios can just talk point-to-point between each other"
Is this a new development? Last I checked this wasn't possible.
Can I connect up little $6 dollar ESP LoRa modules to talk to each other?
The comments here suggest it's not possible: https://www.cnx-software.com/2017/10/13/this-ttgo-board-comb...
You are only feeding Semtech, the Microsoft of Lora, which has the patents on basic information encoding/decoding.
The only gateways you can have which listen on multiple channels are damn expensive.
Isn't LoRa basically just intended to be used one-way/upstream, i.e "node --> gateway --> end-device"? What am I missing?
See ttnmapper.org for the level of coverage and https://www.thethingsnetwork.org/docs/network/architecture.h... for an explanation of "downlink" return messages
I bought two with old screens and don't have any base stations. I beleive they can be connected in mesh with more too (not sure how many channels are needed)!
However LORA itself does work over P2P, and a common module is the ESP32 + LORA + OLED screen, which I have used and tested without any gateways.
Also I think separate from LORA altogether - There's something called ESPNOW which lets the ESP's mesh network, but that's not related to LORA and I haven't ever played with it.
Make sure you get the right frequency for your country to be legal to transmit. 868/915MHz for usa, 433 for euro.
 - https://docs.exploratory.engineering/lora/dr_sf
End devices hop over multiple channels. Most gateways can receive simultaneously on 8, 16 or up to 64 channels (using 1, 2 or up to 8 antennas). The network can dynamically adapt the channels used by each end device to distribute traffic over the available channels.
End devices will use different data rates (spreading factors) for their transmissions (depending on required range). The LoRa modulation allows gateways to receive multiple transmissions on the same channel simultaneously if those transmissions use different spreading factors (most of the time, the spreading factors are "almost orthogonal").
You can deploy more gateways to create smaller cells. The network can then tell end devices to lower their transmit power.
More details in this video: https://privatevideos.hubs.vidyard.com/watch/iXBL8d2mjyjubK8...
If you deploy a private LoRaWAN network with your own gateways and your own servers, you only need to comply with the limits imposed by local regulators for the (unlicensed) spectrum you're using. In Europe's 868MHz ISM band, transmitters are limited by a 1% duty cycle. In the US's 915MHz band, transmissions are limited to a 400ms dwell time. Other regions have similar limits.
Ti's long range 15.4 implementation is not open but is much cheaper than LoRa, you just need two $20 Launchpad boards, one as a basestation and one as your client.
You could also just use the LaunchPad's packet radio api to implement your own simple protocol, you just need to remember to keep to the limitations imposed by the authorities (duty cycle, wait time).
Non-metric units are objectively worse.
The word you're looking for is "subjectively". There are lots of aesthetic reasons to like the metric system but realistically the best one is the one you have internalized.
I for example speak German and English and I can assure you that both these languages have their merits. German is a more precise language with more nuance and a bigger vocabulary, chaining of nouns allows for ad-hoc invention of new words which other people will quickly understand etc. English is much easier to learn, is less clunky to express everyday stuff and it lends itself to certain ways of thinking that I wouldn’t want to miss.
While these are based on subjective observations there is plenty of research that shows how language affects thinking and one could argue there are objective differences.
Are the benifits of metric prefixes, a decimal base, better interfacing with Si units etc really just subjective?
If you live in an imperial world, these benifits might diminish, but using this as an argument would be similar to saying “German is not a good language because where I live it is not spoken”
Yeah now that would be subjectively.
Back to the larger point: if your argument is that it's similar to comparing German and English, you've lost. Bringing it down to effectively a language barrier means it's obviously not worth any switching cost for a few minor conveniences.