High Altitude Balloons (HAB) are a great way to get all kinds of data and shoot great photos and video, but what goes up must come down. Once the equipment has landed, one must track it down. GPS and LoRA, with its long wireless range and ease of use, are invaluable tools in tracking payloads that have returned to Earth. [Dave Akerman] has made handheld receivers to guide him to payloads, but wanted something even smaller; ideally something that could be worn on the wrist.
Enshrined in the hacker hall of fame, the IM-Me was an instant messaging toy that turned out to be extremely hackable. You could easily ditch its instant messaging platform to turn it into a little spectrum analyser. Of course what’s old is new again, and in this age where we no longer have the Nokia 3110, the Sidekick, or even Blackberries, how shall we get our fix of those wireless gadgets with physical keyboards?
There are two versions of the device for hand and pocket, both of which come with QWERTY keyboards made with momentary-action switches, 18650 cell power, and LCD screens. The idea is that it could form a robust communication system when many others have failed.
As it stands they have a simple text messaging app in the firmware, but there are other features yet to come. Perhaps the most interesting is a possible store-and-forward meshing system in the future, which would make this a powerful comms tool in so many circumstances. Both of [Bobricius’] devices can be seen in the video below the break — no word from him on the possibility of a pink case option. Meanwhile [Bobricius] has appeared on these pages many times before. With so many to choose from it’s hard to pick one, but his Nixie-like LED display is quite memorable.
We’re used to LoRa as a free-to-use digital radio protocol allowing not-very-high data rate communications over distances of a few miles. It’s made all kinds of distributed sensor systems a breeze, and some experimenters have made an art of achieving communication over hundreds of miles. But what would happen if you took a brute-force approach to LoRa and simply wound up the power?
For those not familiar with radio propagation, radio waves bounce off some surprising things. In this case the aim was to bounce them off the troposphere, but while radio amateurs and LoRa distance chasers wait until weather conditions deliver a so-called “lift” in which the troposphere is especially reflective, here the experiment was performed under normal flat conditions. The result characterizes LoRa’s possibilities for everyday extreme-range mode rather than chasing records, and in that there were some interesting results. The reflected signal was receivable in bursts with low but consistent signal strength, with the limiting factor during the test as that they ran out of land upon which to drive in the southernmost peninsula of New Jersey. We’ve heard of War-Driving for open WiFi… does this car dashboard setup count as LoRa-Driving?
LoRa is designed as a protocol tolerant of low signal levels and some packet loss, so this experiment is an interesting demonstration of its possibilities when used at higher powers under a licensed transmission. It shouldn’t be possible to use the 70cm band for reliable tropospheric propagation under non-lift conditions, but this shows that it can be done. Meanwhile, take a look at a previous attempt to push LoRa using a balloon.
An ideal application for mesh networking is off-grid communication; when there’s no cellular reception and WiFi won’t reach, wide-area technologies like LoRa can be used to create ad hoc wireless networks. Whether you’re enjoying the outdoors with friends or conducting a rescue operation, a cheap and small gadget that will allow you to create such a network and communicate over it would be a very welcome addition to your pack.
Developer [Kevin Hester] tells us that these are still the very early days, and there’s plenty of work yet to be done. In fact, he’s actively looking to bring a few like-minded individuals onto the project. So if you have experience with the ESP32 or mobile application development, and conducting private communications over long-range wireless networks sounds like your kind of party, this might be your lucky day.
From a user’s perspective, this project is extremely approachable. You don’t need to put any custom hardware together, outside of perhaps 3D printing a case for your particular board. The first time around you’ll need to flash the firmware with esptool.py, but after that, [Kevin] says future updates can be handled by the smartphone application.
Incidentally, the primary difference between the two boards is that the larger and more expensive one includes GPS. The mesh networking side of things will work with either board, but if everyone in your group has the GPS-equipped version, each user will be able to see the position of everyone else in the network.
LoRa is the go-to tech for low power, long range wireless sensor networks. Designing with off-the-shelf modules can be a boon or a bane depending on the documentation and support. Luckily, [Renzo] has prepared a set of tutorials to get you started.
In his seven part series of write-ups, [Renzo] starts by connecting the E32 module from AliExpress to an Arduino as well as an ESP8266 to demonstrate essential communications. Then he discusses the configuration options and the library he created to make like a bit easier. Following that is a series of posts discussing transmission types as well as power saving methods including sleep modes and wake-on-radio.
The information will be extremely handy for someone starting off with the SX1276/SX1278 Wireless Modules which are relatively inexpensive as opposed to more standardized development kits. We love the abundance of fritzing diagrams, arduino code and helper library and hope someone will build on it. You can get the library from Github for your tinkering pleasure.
As more of the world’s communication moves into the electronic realm, a casualty has come in the physical mail. Where once each new day might have brought with it a bulging mailbox, today it’s not uncommon for days to pass with not even so much as a bill or a coupon book. For [Eivholt] this presents a problem: he doesn’t want to miss a parcel but most visits to the mailbox are futile. His solution is a LoRa-connected mailbox monitor that sips power from a pair of AAA batteries to the extent that so far it’s run for over two years on a single set.
At its heart is a single board, a Talk2 Whisper Node. This packs a low-power version of the ATmega328 microcontroller alongside a LoRa radio and an efficient power regulator allowing it to draw only 8.70 uA in standby mode, waking up only for extremely short periods to check for mail and report via LoRa to The Things Network. The sensor is simply a microswitch, selected after finding a reed switch problematic to install. Finally an SDR was used to debug the operation of the radio.
The write-up also provides an introduction to extreme low power projects, including some tips on measuring such tiny currents. Even if you have no interest in a mailbox, any tricks that can help maximize power efficiency are always worth taking a look at. Check out the video after the break to see this radio-equipped mailbox in action.
When you’re looking to add some wireless functionality to a project, there are no shortage of options. You really don’t need to know much of the technical details to make use of the more well-documented modules, especially if you just need to get something working quickly. On the other hand, maybe you’ve gotten to the point where you want to know how these things actually work, or maybe you’re curious about that cheap RF module on AliExpress. Especially in the frequency bands below 1 GHz, you might find yourself interfacing with a module at really low level, where you might be tuning modulation parameters. The following overview should give you enough of an understanding about the basics of RF modulation to select the appropriate hardware for your next project.
Three of the most common digital modulation schemes you’ll see in specifications are Frequency Shift Keying (FSK), Amplitude Shift Keying (ASK), and LoRa (Long Range). To wrap my mechanically inclined brain around some concepts, I found that thinking of RF modulation in terms of pitches produced by a musical instrument made it more intuitive.
And lots of pretty graphs don’t hurt either. Signals from two different RF dev boards were captured and turned into waterfall and FFT plots using a $20 RTL-SDR dongle. Although not needed for wireless experimentation, the RTL-SDR is an extremely handy debugging tool, even to just check if a module is actually transmitting. Continue reading “RF Modulation: Crash Course For Hackers”→