Old Rabbit Ears Optimized for Weather Satellite Downlink

Communicating with a satellite seems like something that should take a lot of equipment. A fancy antenna and racks full of receivers, filters, and amplifiers would seem to be the entry-level suite of gear. But listening to a weather satellite with an old pair of rabbit ears and an SDR dongle? That’s a thing too.

There was a time when a pair of rabbit ears accompanied every new TV. Those days are gone, but [Thomas Cholakov (N1SPY)] managed to find one of the old TV dipoles in his garage, complete with 300-ohm twinlead and spade connectors. He put it to work listening to a NOAA weather satellite on 137 MHz by configuring it in a horizontal V-dipole arrangement. The antenna legs are spread about 120° apart and adjusted to about 20.5 inches (52 cm) length each. The length makes the antenna resonant at the right frequency, the vee shape makes the radiation pattern nearly circular, and the horizontal polarization excludes signals from the nearby FM broadcast band and directs the pattern skyward. [Thomas] doesn’t mention how he matched the antenna’s impedance to the SDR, but there appears to be some sort of balun in the video below. The satellite signal is decoded and displayed in real time with surprisingly good results.

Itching to listen to satellites but don’t have any rabbit ears? No problem — just go find a cooking pot and get to it.

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DEF CON BadgeLife: Blinky Bling

This is the biggest year yet for unofficial electronic conference badges. We’re calling it the year of Badgelife, and for the next few weeks, we’re going to be taking a look at the unofficial conference badges being deployed at this year’s DEF CON.

[Mr Blinky Bling] a.k.a. [Benn Hibben] has created his own badge for this year’s con. On board is a bunch of LEDs, WiFi, and capacitive buttons. It’s a WiFi badge for all your AP scanning and deauth needs. The electronics for this badge are a bit more complicated than simply throwing an ESP8266 on a board and calling the design done. The capacitive touch functionality is being handled by an ATTiny88, the OLED display is handled by an ATMega32U4, wireless functions are done with an ESP8266, and there are a few bits and bobs for a LiPo battery.

This WiFi Badge is the focus of an astonishingly successful Kickstarter (ending in just a few hours), and [Mr Blinky Badge] already has enough backers to move 200 badges. This is really a spectacular amount of work; it’s one thing to build a single prototype for an electronic conference badge, but it’s another matter entirely to put a badge into production, source all the parts, handle the assembly, and finally ship all these badges to Kickstarter backers and conference attendees.

If the challenge of building and deploying hundreds of electronic conference badges sounds like fun, you’re in luck. This Friday, we’ll be hosting a Hack Chat with some of the creators of this year’s unofficial DEF CON badge creators. There’s a lot you can learn from these folks, and a lot of very cool badges that will make an appearance at this year’s Def Con.

Building a Smart Airsoft Gun with Open Source Hardware

[matt8588] designed a smartgun rig for his Airsoft shotgun (YouTube, embedded below). He has a Rasperry Pi 3 mounted inside a PEQ box connected to an infrared camera with an IR tac light helping with illumination. A series of buttons control a crosshair pattern superimposed on the camera image, which is displayed on a tablet. You can also reposition the crosshairs to shoot further away. One of the buttons triggers a signal on the transmitter, for setting off Airsoft claymores during battle. A second Pi, a Zero, connects to an BerryIMU sensor that controls a “traffic light” arrangement of 12mm LEDs that warn him when he’s moving the gun too much to be accurate.

If you want to check out [Matt’s] progress, he’s posted videos of him showing off the gun’s accuracy, including one after the break in which he shoots accurately from a standing position while looking down at the tablet. You can find code for both Pi’s on his GitHub repository.

We suppose it goes without saying that Hackaday has a plethora of Airsoft projects. We especially love the Airsoft sentry gun, the rover-mounted Airsoft gun, and the drone-mounted POV Airsoft turret we published.

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Robot Solves Sudoku on Paper

Sudoku is a great way to pass some time, especially on a long flight. However, we don’t think the airlines will let [Sanahm] board with his sudoku-solving robot. The basic machine looks like a 2D plotter made with aluminum extrusion, with the addition of a Raspberry Pi and a camera. The machine can read a sudoku puzzle, solve it, and then fill in the puzzle with a pen. Unlike humans, it should never need to erase its work.

The software uses OpenCV to process the camera data, find the grid, and the cells provided by the puzzle. TensorFlow recognizes the numbers. From there, it is all just math to solve the puzzle. Once solved, the plotter part of the robot takes over and fills in the blanks. After all that, this seems like the easy part.

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Hackaday Prize Entry: Stroke Rehabilitation Through Biofeedback

Students at Purdue University’s Weldon School of Biomedical Engineering created ExoMIND, an Arduino-powered glove that helps a stroke victim recover by tracking the range of motion the patient experiences.

A set of 7 accelerometers in the fingers, wrist, and forearm track the range of movements the patient is experiencing with that hand. An accelerometer on the back of the hand serving as a reference. Meanwhile, an EMG sensor working with a conductive fabric sleeve to measure muscle activity. The user follows a series of instructions dished out by an interactive software program, allowing the system to test out the patient’s range of motion at the beginning of the regime as well as to record whether any improvement was noted at the end. The data is used by a physical therapist to personalize the treatment plan. The interactive program also raises the possibility of patients self-directing their exercises with the ExoMIND telling them how to adjust their motion to get the most out of the experience.

Produced as part of the university’s MIND Biomedical Engineering Club, the ExoMIND prototype was designed by three interdisciplinary teams focusing on electronics, materials, and programming, respectively.

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Horns Across America: The AT&T Long Lines Network

A bewildering amount of engineering was thrown at the various challenges presented to the United States by the end of World War II and the beginning of the Cold War. From the Interstate Highway System to the population shift from cities to suburbs, infrastructure of all types was being constructed at a rapid pace, fueled by reasonable assessments of extant and future threats seasoned with a dash of paranoia, and funded by bulging federal coffers due to post-war prosperity and booming populations. No project seemed too big, and each pushed the bleeding edge of technology at the time.

Some of these critical infrastructure projects have gone the way of the dodo, supplanted by newer technologies that rendered them obsolete. Relics of these projects still dot the American landscape today, and are easy to find if you know where to look. One that always fascinated me was the network of microwave radio relay stations that once stitched the country together. From mountaintop to mountaintop, they stood silent and largely unattended, but they once buzzed with the business of a nation. Here’s how they came to be, and how they eventually made themselves relics.

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A Live ECU Simulator for OBD2 Projects

If you are working with OBD2 hardware or software, it’s easy enough to access test data, simply plug into a motor vehicle with an OBD2 socket. If, however, you wish to test OBD2 software under all possible fault conditions likely to be experienced by an engine, you are faced with a problem in that it becomes difficult to simulate all faults on a running engine without breaking it. This led [Fixkick] to create an OBD2 simulator using a secondhand Ford ECU supplied with fake sensor data from an Arduino to persuade it that a real engine was connected.

The write-up is quite a dense block of text to wade through, but if you are new to the world of ECU hacking it offers up some interesting nuggets of information. In it there is described how the crankshaft and camshaft sensors were simulated, as well as the mass airflow sensor, throttle position, and speedometer sensors. Some ECU inputs require a zero-crossing signal, something achieved with the use of small isolating transformers. The result is a boxed up unit containing ECU and Arduino, with potentiometers on its front panel to vary the respective sensor inputs.

We’ve brought you quite a few OBD2 projects over the years, for example, there was this LED tachometer, and a way into GM’s OnStar.

Thanks [darkspr1te] for the tip.