LoRa is a communications method that allows for long range radio contacts to be made using typically low-powered devices. This shouldn’t be surprising given that LoRa is short for “long range” which typically involves distances on the order of a few kilometers. However, a group of students are taking the “long range” moniker to the extreme by attempting to send and receive a signal with a total path of around 768,000 kilometers by using some specialized equipment to bounce a LoRa signal off of the moon and receive it back on Earth.
Earth-Moon-Earth (EME) communications are typically done by amateur radio operators as a hobby, since the development of communications satellites largely rendered other uses of this communication pathway obsolete. A directional antenna and a signal typically on the order of 1 kW are often used to compensate for the extremely high path losses. Using LoRa, which makes use of chirp spread spectrum modulation, they hope to reduce this power requirement significantly. The signals are being generated and received on a set of HackRF One devices fed into a series of amplifiers, and the team is also employing a set of large dish antennas, one in New Jersey and another in Alaska, to send and receive the messages.
The software used is the open-source SDRAngel which is useful for controlling the HackRF and moving the LoRa signal up to 1296 MHz. Normally LoRa is operated on an unlicensed band, but this method allows for finer control of not only frequency but also bandwidth, which helps reduce the impacts of path loss. Right now they have not yet completed their contacts with the Alaska station (partially due to that antenna being covered in snow) but we hope to hear more news in the future. In the meantime, take a look at some more traditional long-range communications using this protocol with more manageable-sized antennas.
Image courtesy of NASA, Public domain, via Wikimedia Commons
[Mark Havran] is on a mission to complete a solo trip around the world on his bicycle. For such a long and arduous trip, unsupported by anything other than what he and his bike can carry, he has devised a unique vehicle with everything he needs to accomplish his journey. This bike has plenty of things we’ve seen before, such as solar panels and an electric motor, but plenty of things that are completely novel as well.
For such long-distance trips, the preferred style of bike for most is a recumbent. This allows the rider to take a more relaxed position while riding and is much more efficient than an upright bike as well. [Mark]’s bike also uses a hub motor in the front wheel powered by a set of lithium ion battery packs. The bike also utilizes four solar panels with three charge controllers (to reduce the impacts of panel shading) laid out with three of the panels on a trailer and a single panel above the bike to give him some shade while riding. [Mark] also built solar tracking abilities into each of the two arrays, allowing the solar panels to automatically rotate around the trailer and bike to more efficiently capture sunlight than a statically-mounted set of panels would be able to. They can also be manually controlled in case of high winds.
From the video linked below, we can see a number of other added features to the bike that will enable it to make such a long trip. First, he is getting a new motor which has a number of improvements over his old one, which he put over 30,000 kilometers on. Second, there are some safety features that deserve a mention such as his lighting setup borrowed from emergency response vehicles, and even includes a fire extinguisher for any catastrophic electrical failures. Of course, if you aren’t optimizing your recumbent electric bike for long distance there are some other modifications you could make to it as well to improve its off-road abilities. Best of luck, Mark!
Continue reading “DIY Solar Ebike Goes Around The World, We Hope” →
With its vintage sound, there’s no mistaking the unique 8-bit sound of video games from the 80s and 90s. It became so popular that eventually sparked its own genre of music known as “chiptune” for which musicians are still composing today. The music has some other qualities though, namely that it’s relatively simple from a digital standpoint. [Robots Everywhere] found that this simplicity made it perfect as a carrier for wireless power transmission.
The project acts more like a radio transmitter and receiver than it does a true wireless power transmitter, but the principle is the same. It uses a modified speaker driver and amplifier connected to a light source, rather than to a speaker. On the receiving end, there is a solar panel (essentially a large photodetector) which is wired directly to a pair of earbuds. When the chiptune is played through the amplifier, it is sent via light to the solar panel where it can be listened to in the earbuds.
The project is limited to 24,000 bytes per second which is a whole lot more useful than just beaming random audio files around your neighborhood, although that will still work. You can also use something like this to establish a long-distance serial link wirelessly, which can be the basis of a long distance communications network.
Thanks to [spiritplumber] for the tip!
Continue reading “Chiptunes On A Solar Panel” →