Keep Tabs on Passing Jets with Pi and SDR

Obviously Software Defined Radio is pretty cool. For a lot of hackers you just need the right project to get you into it. Submitted for your approval is just that project. [Simon Aubury] has been using a Raspberry Pi and SDR to record video of planes passing overhead. The components are cheap and most places have planes passing by; this just might be the perfect project.

We’re not just talking static frames with planes passing through them, oh no. Simon used two hobby servos and some brackets to gimbal his Pi camera board. A DVB dongle allows the rig to listen in on the Automatic Dependent Surveillance Broadcast (ADS-B) coming from the planes. This system is mandated for most commercial aircraft (deadlines for implementation vary). ADS-B consists of positioning data being broadcast from planes using known frequencies and protocols. Once [Simon] locks onto this data he can accomplish a lot, like keeping the plane in the center of the video, establishing which flight is being recorded, and automatically uploading the footage. With such a marvelously executed build we’re certain we will see more people giving it a try.

[Simon] did a great job with the writeup too. Not only did he include a tl;dr, but drilled down through a project summary and right to the gritty details. Well done documentation is itself worth celebrating!

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Cairo Hackerspace Gets A $14 Projector

The Cairo hackerspace needed a projector for a few presentations during their Internet of Things build night, and of course Friday movie night. They couldn’t afford a real projector, but these are hackers. Of course they’ll be able to come up with something. They did. They found an old slide projector made in West Germany and turned it into something capable of displaying video.

The projector in question was a DIA projector that was at least forty years old. They found it during a trip to the Egyptian second-hand market. Other than the projector, the only other required parts were a 2.5″ TFT display from Adafruit and a Nokia smartphone.

All LCDs are actually transparent, and if you’ve ever had to deal with a display with a broken backlight, you’ll quickly realize that any backlight will work, like the one found in a slide projector. By carefully removing the back cover of the display, the folks at the Cairo hackerspace were able to get a small NTSC display that would easily fit inside their projector.

After that, it was simply a matter of putting the LCD inside the display, getting the focus right, and mounting everything securely. The presentations and movie night were saved, all from a scrap heap challenge.

An External Autofocus for DSLRs

Most modern DSLR cameras support shooting full HD video, which makes them a great cheap option for video production. However, if you’ve ever used a DSLR for video, you’ve probably ran into some limitations, including sluggish autofocus.

Sensopoda tackles this issue by adding an external autofocus to your DSLR. With the camera in manual focus mode, the device drives the focus ring on the lens. This allows for custom focus control code to be implemented on an external controller.

To focus on an object, the distance needs to be known. Sensopoda uses the HRLV-MaxSonar-EZ ultrasonic sensor for this task. An Arduino runs a control loop that implements a Kalman filter to smooth out the input. This is then used to control a stepper motor which is attached to the focus ring.

The design is interesting because it is rather universal; it can be adapted to run on pretty much any DSLR. The full writeup (PDF) gives all the details on the build.

Hacking VGA for Trippy Video Effects

RGB.VGA.VOLT

Ever since flat panel LCD monitors came on the scene, most old CRTs have found their ways into the garbage or into the backs of closets. For this project, it might be a good idea to pull out the old monitor or TV out and dust it off! [James] has found a way to hack the VGA input to these devices to get them to display vivid visualizations based on an audio input.

The legacy hardware-based project is called RGB.VGA.VOLT and works by taking an audio signal as an input, crossing some wires, and sending the signal through a synthesizer. The circuit then creates a high-frequency waveform that works especially well for being displayed on VGA. The video can also be channeled back through an audio waveform generator to create a unique sound to go along with the brilliant colors.

[James]’s goals with this project are to generate an aesthetic feeling with his form of art and to encourage others to build upon his work. To that end, he has released the project under an open license, and the project is thoroughly documented on his project site.

There have been plenty of hacks in the past that have implemented other protocols with VGA or implemented VGA on microcontrollers, but none that have hacked the interface entirely to create something that looks like the Star Gate sequence from 2001: A Space Odyssey. We think it’s a great piece of modern art and a novel use of VGA!

Thanks for the tip, [Kyle]!

A Raspberry Pi Helmet Cam with GPS Logging

20140126_222809-1 Over the last 20 years, [Martin] has been recording snowboarding runs with a standard helmet cam. It was good but he felt like he could improve upon the design by building his own version and logging additional data values like speed, temperature, altitude, and GPS. In the video shown after the break, a first person perspective is displayed with a GPS overlay documenting the paths that were taken through the snow. [Martin] accomplished this by using a python module called picamera to start the video capture and writing the location to a data file. He then modified the program to read the current frame number and sync GPS points to an exact position in the video. MEncoder is used to join the images together into one media file.

The original design was based on the Raspberry Pi GPS Car Dash Cam [Martin] developed a few months earlier. The code in this helmet cam utilizes many of the same functions surrounding the gathering of GPS data points, recording video, and generating the overlay. What made this project different though were the challenges involved. For example, a camera inside a car rarely has to deal with extreme drops in temperature or the wet weather conditions of a snowy mountain. The outside of the vehicle may get battered from the snow, but the camera remains relatively safe from exposure. In order to test the Raspberry Pi before venturing into the cold, [Martin] stuck the computer in the freezer to see what would happen. Luckily it worked perfectly.

Click past the break for the rest of the story.

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Poor Audio Quality Made Great: Listen to Vintage Music Using an Antique Radio Without Removing the Insides

Sometimes it is not how good but how bad your equipment reproduces sound. In a previous hackaday post the circuitry of a vintage transistor radio was removed so that a blue tooth audio source could be installed and wired to the speaker. By contrast, this post will show how to use the existing circuitry of a vintage radio for playing your own audio sources while at the same time preserving the radio’s functionality. You will be able to play your music through the radio’s own audio signal chain then toggle back to AM mode and listen to the ball game. Make a statement – adapt and use vintage electronics.

Pre-1950’s recordings sound noisy when played on a high-fidelity system, but not when played through a Pre-War console radio. An old Bing Crosby tune sounds like he is broadcasting directly into your living room with a booming AM voice. You do not hear the higher frequency ‘pops’ and ‘hiss’ that would be reproduced by high-fidelity equipment when playing a vintage recording. This is likely due to the fact that the audio frequency signal chain and speaker of an antique radio are not capable of reproducing higher frequencies. Similarly, Sam Cooke sounds great playing out of an earlier transistor radio. These recordings were meant to be played on radios from the era in which they were recorded.

Choosing an Antique Radio

Vintage radios can be found at garage sales, estate sales, hamfests, antique shops, antique radio swap meets, and Ebay. Millions of radios have been manufactured. People often give them away. For this reason, antique radios are relatively inexpensive and the vast majority are not rare or valuable.

Generally speaking, tube radios must be serviced and may not even work. Transistor radios often work to some level. Try to find a radio that is clean and uses a power supply transformer or batteries.

Click past the break to learn how to restore these radios to working condition

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THP Entry: A CPLD Video Card With VGA And NTSC

NTSC

[PK] is working on a very simple video card, meant to output 640×480 VGA with a cheap CPLD. The interface will be 5 Volt SPI, meaning there’s a ton of potential here for anyone wanting put a reasonable (and cheap) display in a microcontroller project. The project has come a long way, and his latest update showcases something that has only been done once before: color NTSC with programmable logic

The brains of the outfit is a $5, 100-pin CPLD from Xilinx. Apart from that, the rest of the components are a crystal, PLL, and an almost hilarious number of resistors for the R2R ladder. The one especially unique component is the 25.056815 MHz crystal – multiply by that by two, and it’s fast enough to drive a VGA monitor. Divide the crystal by seven, it’s the 3.579545 MHz you need for an NTSC colorburst frequency. That’s VGA and NTSC in a single programmable logic project, something the one FPGA project we could find that did color NTSC couldn’t manage.

The next step in the project is designing a PCB and figuring out the code for the framebuffer. [PK] put up a demo showing off both VGA and NTSC; you can check that out below.


SpaceWrencherThe project featured in this post is an entry in The Hackaday Prize. Build something awesome and win a trip to space or hundreds of other prizes.

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