Ethernet Goes To The Ether

November 9, 2020 by Al Williams 14 Comments

Since the ether is an old term for the fictitious space where radio waves propagate, we always thought it was strange that the term ethernet refers to wired communication. Sure, there are wireless devices, but that’s not really ethernet. [Jacek] had the same thought, but decided to do something about it.

What he did is use two different techniques to alter the electromagnetic emission from an ethernet adapter on a Raspberry Pi. The different conditions send Morse code that you can receive at 125 MHz with a suitable receiver.

Practical? Hardly, unless you are looking to exfiltrate data from an air-gapped machine, perhaps. But it does have a certain cool factor. The first method switches the adapter between 10 Mbps and 100 Mbps. The second technique uses a stream of data to accomplish the modulation. The switching method had a range of around 100 meters while the data-based method topped out at about 30 meters. The code is on GitHub if you want to replicate the experiment.

There is plenty of precedent for this sort of thing. In 1976 Dr. Dobb’s Journal published an article about playing music on an Altair 8800 by running code while an AM radio was nearby. We’ve seen VGA adapters forced to transmit data, too.

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Easy-SDR Gets Updates

October 30, 2020 by Al Williams 1 Comment

Back in 2018, we covered [Igor’s] Easy-SDR project that aimed to provide open hardware extensions for the chap RTL-SDR receivers. If you haven’t been there for a while, it’s worth a look as there have been many recent updates. According to the author’s Reddit post:

Most of the devices are now prepared for installation in a metal case measuring 80 x 50 x 20 millimeters.
There’s a completely redesigned LNA design. Now, Bias Tee powered amplifiers are housed in a 50 x 25 x 25mm metal case and have N-type connectors.
There’s an added amplifier based on the PGA-103 microcircuit.
Added is the ability to install filters in final amplifiers (a separate printed circuit board, depending on the filter used).
A new device – SPDT antenna switch for receiving antennas.
The upconverter has been redesigned. Added intermediate buffer stage between the crystal generator and mixer.
RF lines in all devices were recalculated to correspond to the characteristic wave impedance of 50 Ohm.
Reduced size of PI attenuator PCB.

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Clara Rockmore. Photo by Renato Toppo, © The Nadia Reisenberg / Clara Rockmore Foundation

The Theremin Is 100 Years Old; Celebrating The Spookiest Of Instruments

October 30, 2020 by Kristina Panos 16 Comments

It wouldn’t be October without Halloween, and it wouldn’t be Halloween without some spooky music. There’s no instrument spookier than a Theremin, which also happens to be one of the world’s first electronic instruments.

Leon Theremin plays his namesake instrument. Image via Linda Hall Library

You’ve no doubt heard the eerie, otherworldly tones of the Theremin in various 1950s sci-fi films, or heard the instrument’s one-of-a-kind cousin, the Electro-Theremin in “Good Vibrations” by the Beach Boys. The Theremin turns 100 years old this month, so we thought we’d take a look at this strange instrument.

One hundred years ago, a young Russian physicist named Lev Sergeyevich Termen, better known as Leon Theremin, was trying to invent a device to measure the density of various gases. In addition to the standard analog needle readout, he wanted another way to indicate the density, so he devised an oscillator whistle that would change pitch based on the density.

He discovered by accident that having his hand in the field of the antenna changed the pitch of the whistle, too. Then he did what any of us would do — played around until he made a melody, then called everyone else in the lab over to check it out.

Theremin soon showed his device to Lenin, who loved it so much that he sent Lev on a world tour to show it off. While in New York, he played it for Rachmaninoff and Toscanini. In fact you can see a video recording of Leon playing the instrument, a performance that’s more hauntingly beautiful than spooky. In 1928, he patented the Theremin in the United States and worked with RCA to produce them.

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Tracking Satellites With A Commodore PET

October 29, 2020 by Chris Lott 16 Comments

A recent writeup by Tom Nardi about using the 6502-based NES to track satellites brought back memories of my senior project at Georgia Tech back in the early 80s. At our club station W4AQL, I had become interested in Amateur Radio satellites. It was quite a thrill to hear your signal returning from space, adjusting for Doppler as it speeds overhead, keeping the antennas pointed, all while carrying on a brief conversation with other Earth stations or copying spacecraft telemetry, usually in Morse code.

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Radio Remote Control Via HTML5

October 24, 2020 by Adam Zeloof 36 Comments

It’s a common scene: a dedicated radio amateur wakes up early in the morning, ambles over to their shack, and sits in the glow of vacuum tubes as they call CQ DX, trying to contact hams in time zones across the world. It’s also a common scene for the same ham to sit in the comfort of their living room, sipping hot chocolate and remote-controlling their rig from a laptop. As you can imagine, this essentially involves a server running on a computer hooked up to the radio, which is connected via the internet to a client running on the laptop. [Olivier/ F4HTB] saw a way to improve the process by eliminating the client software and controlling the rig from a web browser.

[Oliver]’s software, aptly named Universal HamRadio Remote, runs a web server that hosts an HTML5 dashboard for controlling the radio. It also pipes audio back and forth (radio control wouldn’t be very useful if you couldn’t talk!), and can be run on a Raspberry Pi. Not only does this make setup easier, as there is no need to configure the client machine, but it also makes the radio accessible from nearly any modern device.

We’ve seen a similar (albeit expensive and closed-source) solution, the MFJ-1234, before, but it’s always refreshing to see the open-source community tackle a problem and make it their own. We can’t wait to see where the project goes next!

Tracking Boats And Ships In Real Time At The Same Time

October 22, 2020 by Bryan Cockfield 15 Comments

Software-defined radio came on the hacker scene in a big way less than a decade ago thanks to the discovery that a small USB-based TV tuner dongle could be used for receiving all kinds of radio transmissions. Two popular projects from that era are tracking nearby airplanes and boats in real time. Of course, these projects rely on different frequencies and protocols, but if you live in a major port city like [Ian] then his project that combines both into a single user interface might be of interest.

This project uses an RTL-SDR dongle for the marine traffic portion of the project, but steps up to a FlightAware Pro dongle for receiving telemetry from airplanes. Two separate antennas are needed for this, and all of the information is gathered and handled by a pair of Raspberry Pis. The Pis communicate with various marine and air traffic databases as well as handles the custom user interface that knits both sets of information together. This interface was custom-built from a previous project of his and was repurposed slightly to fit the needs of this one.

This is a great project that goes into a lot of interesting detail about how the web traffic moves and how the UI works, so even if you’re not into software-defined radio it might be worth a look. However, it’s also worth noting that it hasn’t been easier to set up a system like this thanks to the abundance and low price of RTL-SDR dongles and the software tools that make setting them up a breeze.

It Came From Outer Space: Listening To The Deep Space Network

October 17, 2020 by Adam Zeloof 26 Comments

Ham radio operators love to push the boundaries of their equipment. A new ham may start out by making a local contact three miles away on the 2m band, then talk to somebody a few hundred miles away on 20m. Before long, they may find themselves chatting to fellow operators 12,000 miles away on 160m. Some of the adventurous return to 2m and try to carry out long-distance conversations by bouncing signals off of the Moon, waiting for the signal to travel 480,000 miles before returning to Earth. And then some take it several steps further when they listen to signals from spacecraft 9.4 million miles away.

That’s exactly what [David Prutchi] set out to do when he started building a system to listen to the Deep Space Network (DSN) last year. The DSN is NASA’s worldwide antenna system, designed to relay signals to and from spacecraft that have strayed far from home. The system communicates with tons of inanimate explorers Earth has sent out over the years, including Voyager 1 & 2, Juno, and the Mars Reconnaissance Orbiter. Because the craft are transmitting weak signals over a great distance (Voyager 1 is 14 billion miles away!), the earth-based antennas need to be big. Real big. Each of the DSN’s three international facilities houses several massive dishes designed to capture these whispers from beyond the atmosphere — and yet, [David] was able to receive signals in his back yard.

Sporting a stunning X-band antenna array, a whole bunch of feedlines, and some tracking software, he’s managed to eavesdrop on a handful of spacecraft phoning home via the DSN. He heard the first, Bepi-Colombo, in May 2020, and has only improved his system since then. Next up, he hopes to find Juno, and decode the signals he receives to actually look at the data that’s being sent back from space.

We’ve seen a small group of enthusiasts listen in on the DSN before, but [David]’s excellent documentation should provide a fantastic starting point for anybody else interested in doing some interstellar snooping.