Tech

Remember Sure-Fi? Lostik is open standards Lora you can play with

Enlarge / Lostik is plugged in to the left USB port of this Samsung Chromebook running GalliumOS Linux. It's currently transmitting packets, using the sample sender.py utility, from a basement about 15 feet underground.Jim Salter

A lot of readers commented on our earlier report on Sure-Fi long-range, low-bandwidth RF chirp communicators that we should test generic Lora gear. Lora is the open standard that Sure-Fi began with and built on top of, and it's available in a variety of inexpensive kits. Most of those kits are aimed at low-level maker-style integration with IoT gear like Arduino, but I found a couple of preassembled kits with generic USB interfaces suitable for use with regular x86 computers. One of those, Lostik, had consistently better user reviews and glowingly boasted of its "extensive documentation," so we picked a pair up for $46 apiece and got to testing.

We should be clear about one thing up front—nobody should claim that any Lora device has "extensive documentation" with a straight face. Lostik seems to have more documentation than any of its competitors, but figuring out what exactly what it would do felt like learning to play pirated video games in the 1980s. What we eventually discovered was that Lora devices are sort of like dial-up modems all connected to a single party line—they run on serial interfaces over which they can be issued commands and can send or receive data.

It's possible to use a generic terminal emulator (at 57,600bps, 8 data bits, 1 stop bit, and no parity) to communicate directly with Lostik, but you'll need to understand its commands—analogous to the Hayes AT modem commands of yore—if you do. That was a bridge too far for us, so we said the heck with it and just lightly modified the ./sender.py and ./receiver.py sample scripts from Lostik's Github repository and used them for some simple range testing. These scripts don't require (or offer) any kind of authentication or pairing; any Lora device running receiver.py will successfully receive data from any Lora device running sender.py within its effective range.

  • The HVAC system and its controller are both entirely underground, 104 feet away from each other as measured by Google Maps. There is no passageway between the separate basements. Jim Salter
  • The HVAC controller is in the basement level of the adjacent building, just down a hall to the left. Ground level is just under the window you can see above the landing, about fifteen feet overhead. Jim Salter
  • Lostik couldn't quite cut the mustard between the basement of the facility in the background and the "HVAC dungeon" at the bottom of these stairs. Jim Salter
  • Although Lostik lost connection at the bottom of the stairs, it ran fine from the top—and it's still connected to a sender 15 feet below ground and 100 feet away. Jim Salter
  • SCIENCE! Well, sorta. You can see receiver.py in the background, along with our notes about where it was physically during each packet interval. Jim Salter

After fiddling for a couple of hours getting Lostik working, our first real test was taking it down to the same test facility we used to put Sure-Fi through its paces. If you didn't read our earlier Sure-Fi article, this facility has test sites about 100 feet apart in unconnected subterranean floors under two separate buildings. Unlike Sure-Fi, Lostik couldn't quite cut the mustard between the two basements—it dropped all but the first three packets after we walked the receiver unit downstairs at the second site. It did reconnect again at the top of the stairs, though, and never dropped a single packet from there.

Although these results don't quite match Sure-Fi's range at this site, we need to stress that they're still impressive. The sending unit is still fifteen feet underground and more than 100 feet away—you can't even catch a bare hint of the BSSIDs of the Wi-Fi access point near the sending Lostik unit, but Lostik itself reads loud and clear with never a dropped packet.

  • The rusty iron silo on our left is 300 feet from the Lostik sender in the living room. There's a grove of trees in the line of sight between silo and house.
  • We're holding Lostik's receiver at arm's length inside this rusty iron silo, 300 feet and a grove of trees away from the sending Lostik inside the house. No dropped packets. Jim Salter
  • The edge of the clearing here is 550 feet away from the Lostik receiver. Due to ground slope, there's no clear line of sight from receiver to house. No dropped packets. Jim Salter

Next up, our Lostik units and laptops went to my parents' house where Sure-Fi got its longest-range tests. The sending Lostik unit sat in the living room, while the receiver roamed around to test connectivity through distance and obstructions. Inside the roughly five-acre clearing the house occupies one corner of, coverage was flawless. The longest-range shot inside the "yard" is 550 feet away, with about ten feet of ground swell between the receiver (at ground level) and the sender inside the house. The really fun shot, though, was from inside the big rusty iron silo—three hundred feet, a grove of trees, and structural iron walls weren't enough to make Lostik skip a beat!

Although there aren't any fun action shots, we also tramped around inside the woods anRead More – Source

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