WiFi and Bluetooth have their use cases, but both have certain demands on things like battery life and authentication that make them unsuitable for a lot of low-power use cases. They’re also quite limited in range. There are other standards out there more suitable for low-power and wide area work, and thankfully, LoRa is one of them. Having created some LoRa pagers, [Moser] decided to head out and test their range.
Now, we’ve done range tests before. Often this involves sending one party out with a radio while the other hangs back at base. Cellphones serve as a communications link while the two parties go back and forth, endlessly asking “Is it working now? Hang on, I’ll take a few steps back — what about now?”
It’s a painful way to do a range test. [Moser]’s method is much simpler; set a cellphone to log GPS position, and have the pager attempt to send the same data back to the base station. Then, go out for a drive, and compare the two traces. This method doesn’t just report straight range, either — it can be used to find good and bad spots for radio reception. It’s great when you live in an area full of radio obstructions where simple distance isn’t the only thing affecting your link.
Build details on the pagers are available, and you can learn more about LoRa here. While you’re at it, check out the LoRa tag for more cool builds and hacks.
4 miles, not bad. Which data rate and which modulation was being used?
datarate: probably around 5 to 35 bits/second peak – depending on bandwidth of spectrum
occupied by chirp and the spreading factor (bits encoded per symbol)
modulation: Chirp Spread Spectrum (CSS) you could think of it as a form of radar, in fact I wonder *ponder*
Lots of great information here: http://www.jailbreaksecuritysummit.com/s/Reversing-Lora-Knight.pdf
Interesting read, but the aliexpress pages for the sx1276 / 1278 modules tested here advertise support for other modulations in addition to “lora”, and data rates from 0.018 to 38.4 kbps, so if I wanted to replicate this person’s range (which is close to the claimed ranges on seller pages) what parameters would I need to set?
I figure I’d need about 5kbps (so 9.6 next available option) to implement RC tx/rx LRS modules (for RC models / drones) using these sx1276 boards with an update rate of about 50Hz. Could I still expect this sort of range at 9.6kbps? That would be great because with proper RC hobby antennas and being much higher over ground than the car used in this test, I could probably get multiple times that range in actual aerial use.
Have a look at RFM95. It supports all kinds of FSK, OOK and LoRa.
You know that hopeRF products are just re-branded chips right? Look at the SX1276 datasheet and look at the RFM95 datasheet ;p
” Cellphones serve as a communications link while the two parties go back and forth, endlessly asking “Is it working now? Hang on, I’ll take a few steps back — what about now?””
And now I have a Verizon Wireless commercial going through my head
What’s the deal with LoRa if you want to have a “hub” communicating with a bunch of “remotes”? (Simple hub-star topology, not mesh/repeat – that will be the next question). Does this require some sort of “license” for proprietary software and/or proprietary hardware? How does this technology “scale” and what’s open-source and not? I’ve glanced at this LoRa stuff a few times but I don’t get what I’m asking about here. I see LoRa “gateways” devices that cost hundreds of dollars. Or maybe I just didn’t spend enough time reading(?) Thanks for any substantive replies…
No license required. The gateways have a much more capable multi channel chip inside. You can build your own with a raspberry pi for about €200. http://www.thethingsnetwork.org is a free backend you can connect your gateway to. That way you can yse everyone’s gateway and everyone can use yours. You can also roll your own backend with open source projects like the things network or for example https://github.com/brocaar
@Richard Ginus, Thanks for the info. I’ve glanced at these projects in the past but (obviously) haven’t dug deep enough. Your post is useful (to me anyway).
The deal is that it is just another license-free spectrum standard but with a fancy modulation that gives it a better link budget than dumb (G)FSK (for example: better range or smaller antenna or lower power). It is also standarized on the MAC-level, which means that LoRa gateways should receive data from any kind of device, but higher layers are not standarized (MAC also handles confirmation). You can receive the packets and get them over Ethernet or MQTT, but you have to figure out what to do with the payload later on. It does not solve multiple access, so if you have a couple hundred devices operating in the sam area they will be swamping the spectrum for each other, but nicely rejecting narrowband FSK and non-LoRa interference. In my opinion it scales as well as all low-power ISM modules (ie. does not), just the range is better. You may also be interesting in researching “The Things Network”.
Very cool. Doing a bunch of testing with my own project (FaradayRF) but we use 2-FSK modulation and get a few miles in most cases. With a dedicated base-station antenna with some altitude like 100ft we easily see 10+ miles (horizon). One test with 600ft elevation on a hill we saw 24 miles reliably. It’s tempting one day to support LoRa modulation by writing some code to make a LoRa transceiver talk to my software over localhost/network in a compatible format.
We put up a few balloons carrying a Microchip RN2483 module, and we have reached multiple gateways between 200 and 300 KM this way ;) There was even a fellow in Switzerland that achieved 300 KM+ from a mountain top with a Yagi-Uda. We also have some ground based LoRa devices in Africa that have no trouble transmitting over 10 – 15 KM. We tend to stick to spreading factor 10 and below, to save power.