All Your SDR Software In A Handy Raspberry Pi Image

December 20, 2019 by Jenny List 29 Comments

The SDR revolution has brought a bonanza of opportunities for experimentation to the radio enthusiast, but with it has come a sometimes-confusing array of software for which even installation can be a difficult prospect for an SDR novice. If you’re bamboozled by it all then help may be at hand courtesy of [Luigi Cruz], who has packaged a suite of ready-to-go popular SDR software in an OS image for the Raspberry Pi.

On board the Raspbian-based OS image are SDR Angel, Soapy Remote, GQRX, GNURadio, LimeUtil, and LimeVNA. In hardware terms the RTL-SDR is supported, along with the LimeSDR, PlutoSDR, Airspy, and Airspy HF. All are completely ready-to-go and even have desktop shortcuts, so if the CLI scares you then you can still dive in and play. More importantly it’s designed for use with SDR transmitters as well as receivers, so the barrier for full SDR operation for radio amateurs has become significantly lower too.

This year has seen the seven-year anniversary of the RTL-SDR hack that probably did most to kickstart the use of SDRs in our community. Our colleague [Tom Nardi] wrote a retrospective that’s worth a look for its overview of some SDR tricks that have evolved over that time. Meanwhile if you don’t mind restricting your outlook somewhat, it’s possible to turn the Raspberry Pi 3 into an SDR all without any extra hardware.

Santa Claws: Sharpen Your Skills For A Good Cause

December 18, 2019 by Kristina Panos 2 Comments

Want to do a bit of good this holiday season without leaving your couch or battle station? Well step right up and try your hand at Santa Claws, the charitable claw machine created by UK-based firm Liberty Games. For every toy you can maneuver to the chute, Liberty Games will donate money to Crisis, a national charity devoted to ending homelessness.

The machine is filled with special Christmas-themed stuffed animals that represent different cash values from £1 to £5. And these toys are doing double duty — after the holiday, they’ll all be donated to a good cause. In order to make this playable worldwide, Liberty used a Raspberry Pi, two Pi Face boards to interface the claw machine’s controls, and a Pi Face rack to everything together. They have the machine set on ‘generous’, so go have fun.

Has this rekindled a longing for your own claw machine? Yeah, us too. Here’s a full-size machine that runs on a Teensy.

Not-Quite-So-Hot Stuff: A Thermal Exam On The Latest Raspberry Pi

December 6, 2019 by Jenny List 53 Comments

When the Raspberry Pi 4 was first launched, one of its few perceived flaws was that it had a propensity to get extremely hot. It’s evidently something the Pi people take very seriously, so in the months since they have addressed the problem with a set of firmware updates. Now they’ve taken a look at the effect of the fixes in a piece on the Raspberry Pi web site, and it makes for an interesting comparison.

The headline figure is that all updates together remove about a watt of power from the load, a significant quantity for what is still a board that can run from a capable phone charger. Breaking down the separate parts of the updates is where the meat of this story lies though, as we see the individual effects of the various USB, memory, power management and clocking updates. In temperature terms they measure an on-load drop from 72.1 °C to 58.1 °C, which should be a significant improvement for any Pi 4 owner.

There is a debate to be had over in what role a computer such as a Pi should serve. As successive revisions become ever more desktop-like in their capabilities, do they run the risk of abandoning the simplicity of a cheap Linux box as a component that makes us come back for more? It’s a possibility, but one they have very well addressed by developing the Pi Zero. They have also successfully avoided the fate of the Arduino — inexorably tied to its ATmega powered original line despite newer releases. As we have frequently said when reviewing Raspberry Pi competitors, it’s the software support that sets them apart from the herd, something this power-draw story demonstrates admirably.

1984 WeatherMan Pi Shows The Ch-Ch-Ch-Ch-Changes

December 5, 2019 by Kristina Panos 8 Comments

When [MisterM]’s MIL gave him a rad 80s portable cassette player, he jumped for joy. Once he figured out the window was exactly the same size as the standard for Raspberry Pi HATs, the possibilities left him reeling. A flurry of ideas later, he settled on a weather display featuring a Pimoroni Unicorn HAT HD.

The 1984 Weatherman Pi pulls data from the Dark Sky API every 1.5 seconds using a Zero W. [MisterM] chose to highlight the current temperature, conditions, and rain probability, though there are heaps of other API goodies still on the table. It shows the current weather conditions as animations, scrolls the temperature, and gives a nice graph of rainfall probability.

Surprisingly, the dazzling display isn’t our favorite part. See those spongy headphones up top? They’re not just for decoration, though they go a long way in helping the cassette player keep its identity. Whenever there’s a change in the weather, they shimmy back and forth on a 9g servo. If the servo were continuous, it might be neat to use them as a weather vane.

Be sure to check out [MisterM]’s comprehensive demo/build video waiting for you on the B-side. We love a good weather display around here, and the more colorful and literal, the better.

Continue reading “1984 WeatherMan Pi Shows The Ch-Ch-Ch-Ch-Changes” →

A Thermal Typewriter For Burning Thoughts

December 5, 2019 by Kristina Panos 15 Comments

There’s a certain charm to old technologies that have been supplanted by newer versions. And we’re not just talking about aesthetic nostalgia this time. With older versions of current technology, you are still connected to the underlying process, and that’s a nice feeling.

Part of the typewriter’s charm is in its instant permanence. These days, its so easy to backspace, delete, and otherwise banish thoughts to the void without giving them a fair trial, though it’s nice not to have to pound the keys to make an impression. At the typewriter, your words are immediately committed to paper, for better or worse. You can usually see them pretty well, although maybe not on the current line, and that is good for letting the words flow without judgment.

[Murtaza Tunio] recently used a thermal POS printer in an art project, but it had since grown cold with disuse. Why not turn it into a typewriter? All it took was a Raspberry Pi, a USB keyboard, and an existing Python library for communicating with these parallel printers. Typing is a bit challenging for a few reasons. For one thing, [Murtaza] has to type five lines before the words become visible. The enter key doesn’t come across for some reason, so a different one had to be assigned. On the upside, [Murtaza] can trigger the paper cutter with a keystroke.

Not too hot on thermal printers? You might find this e-ink typewriter refreshing.

Robot Vs. Superbug

November 30, 2019 by Bryan Cockfield 6 Comments

Working in a university or research laboratory on interesting, complicated problems in the sciences has a romanticized, glorified position in our culture. While the end results are certainly worth celebrating, often the process of new scientific discovery is underwhelming, if not outright tedious. That’s especially true in biology and chemistry, where scaling up sample sizes isn’t easy without a lot of human labor. A research group from Reading University was able to modify a 3D printer to take some of that labor out of the equation, though.

This 3D printer was used essentially as a base, with the printing head removed and replaced with a Raspberry Pi camera. The printer X/Y axes move the camera around to all of the different sample stored in the print bed, which allows the computer attached to the printer to do most of the work that a normal human would have had to do. This allows them to scale up massively and cheaply, presumably with less tedious inputs from a large number of graduate students.

While the group hopes that this method will have wide applicability for any research group handling large samples, their specific area of interest involves researching “superbugs” or microbes which have developed antibiotic resistance. Their recently-published paper states that any field which involves bacterial motility, colony growth, microtitre plates or microfluidic devices could benefit from this 3D printer modification.

Raspberry Pi 4 HDMI Is Jamming Its Own WiFi

November 28, 2019 by Bryan Cockfield 87 Comments

Making upgrades to a popular product line might sound like a good idea, but adding bigger/better/faster parts to an existing product can cause unforeseen problems. For example, dropping a more powerful engine in an existing car platform might seem to work at first until people start reporting that the increased torque is bending the frame. In the Raspberry Pi world, it seems that the “upgraded engine” in the Pi 4 is causing the WiFi to stop working under specific circumstances.

[Enrico Zini] noticed this issue and attempted to reproduce exactly what was causing the WiFi to drop out, and after testing various Pi 4 boards, power supplies, operating system version, and a plethora of other variables, the cause was isolated to the screen resolution. Apparently at the 2560×1440 setting using HDMI, the WiFi drops out. While you could think that an SoC might not be able to handle a high resolution, WiFi, and everything else this tiny computer has to do at once. But the actual cause seems to be a little more interesting than a simple system resources issue.

[Mike Walters] on a Twitter post about this issue probed around with a HackRF and discovered a radio frequency issue. It turns out that at this screen resolution, the Pi 4 emits some RF noise which is exactly in the range of WiFi channel 1. It seems that the Pi 4 is acting as a WiFi jammer on itself.

This story is pretty new, so hopefully the Raspberry Pi Foundation is aware of the issue and working on a correction. For now, though, it might be best to run a slightly lower resolution if you’re encountering this problem.