A DIY EMC Probe From Semi-Rigid Coax And An SDR

April 24, 2019 by Dan Maloney 17 Comments

Do you have an EMC probe in your toolkit? Probably not, unless you’re in the business of electromagnetic compatibility testing or getting a product ready for the regulatory compliance process. Usually such probes are used in anechoic chambers and connected to sophisticated gear like spectrum analyzers – expensive stuff. But there are ways to probe the electromagnetic mysteries of your projects on the cheap, as this DIY EMC testing setup proves.

As with many projects, [dimtass]’ build was inspired by a video over on EEVblog, where [Dave] made a simple EMC probe from a length of semi-rigid coax cable. At $10, it’s a cheap solution, but lacking a spectrum analyzer like the one that [Dave] plugged his cheap probe into, [dimtass] went a different way. With the homemade probe plugged into an RTL-SDR dongle and SDR# running on a PC, [dimtass] was able to get a decent approximation of a spectrum analyzer, at least when tested against a 10-MHz oven-controlled crystal oscillator. It’s not the same thing as a dedicated spectrum analyzer – limited bandwidth, higher noise, and not calibrated – but it works well enough, and as [dimtass] points out, infinitely hackable through the SDR# API. The probe even works decently when plugged right into a DSO with the FFT function running.

Again, neither of these setups is a substitute for proper EMC testing, but it’ll probably do for the home gamer. If you want to check out the lengths the pros go through to make sure their products don’t spew signals, check out [Jenny]’s overview of the EMC testing process.

[via RTL-SDR.com]

Radio Free Blockchain: Bitcoin From Space

April 2, 2019 by Dan Maloney 31 Comments

Cryptocurrencies: love them, hate them, or be baffled by them, but don’t think you can escape them. That’s the way it seems these days at least, with news media filled with breathless stories about Bitcoin and the other cryptocurrencies, and everyone from Amazon to content creators on YouTube now accepting the digital currency for payments. And now, almost everyone on the planet is literally bathed in Bitcoin, or at least the distributed ledger that makes it work, thanks to a new network that streams the Bitcoin blockchain over a constellation of geosynchronous satellites.

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Eavesdropping On Cosmonauts With An SDR

March 28, 2019 by Dan Maloney 9 Comments

Usually when we hear about someone making contact with astronauts in orbit, it’s an intentional contact between a ham on the ground and one of the licensed radio amateurs on the ISS. We don’t often see someone lucky enough to snag a conversation between ground controllers and a spacecraft en route to the ISS like this.

For [Tysonpower], this was all about being in the right place at the right time, as well as having the right equipment and the know-how to use it properly. Soyuz MS-12 launched from Baikonur on March 14 with cosmonaut [Aleksey Ovchinin] and NASA astronauts [Nick Hague] and [Kristina Koch] onboard, destined for the ISS after a six-hour flight. The lucky bit came when [Tysonpower] realized that the rendezvous would happen when the ISS was in a good position relative to his home in Cologne, which prompted him to set up his gear for a listening session. His AirSpy Mini SDR was connected to a home-brew quadrifilar helical (QFH) “eggbeater” antenna on his roof. What’s nice about this antenna is that it’s fixed rather than tracking, making it easy to get on the air with quickly. After digging around the aviation bands at about 121 MHz for a bit, [Tysonpower] managed to capture a few seconds of a conversation between [Ovchinin] and Moscow Flight Control Center. The commander reported his position and speed relative to the ISS a few minutes before docking. The conversation starts at about 1:12 in the video below.

We think it’s just cool that you can listen in on the conversations going on upstairs with a total of less than $50 worth of gear. Actually talking to the hams aboard the ISS is another matter, but not a lot more involved really.

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WOPR: Security Loses Some Of Its Obscurity

March 28, 2019 by Tom Nardi 11 Comments

As we’ve seen time and time again, the word “hacker” takes on a different meaning depending on who you’re talking to. If you ask the type of person who reads this fine digital publication, they’ll probably tell you that a hacker is somebody who likes to learn how things work and who has a penchant for finding creative solutions to problems. But if you ask the average passerby on the street to describe a hacker, they might imagine somebody wearing a balaclava and pounding away at their laptop in a dimly lit abandoned warehouse. Thanks, Hollywood.

Naturally, we don’t prescribe to the idea of hackers being digital villains hell-bent on stealing your identity, but we’ll admit that there’s something of rift between what we call hacking versus what happens in the information security realm. If you see mention of Red Teams and Blue Teams on Hackaday, it’s more likely to be in reference to somebody emulating Pokemon on the ESP32 than anything to do with penetration testing. We’re not entirely sure where this fragmentation of the hacking community came from, but it’s definitely pervasive.

In an attempt bridge the gap, the recent WOPR Summit brought together talks and presentations from all sections of the larger hacking world. The goal of the event was to show that the different facets of the community have far more in common than they might realize, and featured a number of talks that truly blurred the lines. The oscilloscope toting crew learned a bit about the covert applications of their gadgets, and the high-level security minded individuals got a good look at how the silicon sausage gets made.

Two of these talks which should particularly resonate with the Hackaday crowd were Charles Sgrillo’s An Introduction to IoT Penetration Testing and Ham Hacks: Breaking into Software Defined Radio by Kelly Albrink. These two presentations dealt with the security implications of many of the technologies we see here at Hackaday on what seems like a daily basis: Bluetooth Low Energy (BLE), Software Defined Radio (SDR), home automation, embedded Linux firmware, etc. Unfortunately, the talks were not recorded for the inaugural WOPR Summit, but both presenters were kind of enough to provide their slides for reference.

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EBay Modules And Custom PCBs Make A Plug And Play Ham Transceiver

March 17, 2019 by Dan Maloney 9 Comments

Many of us have fond memories of our introduction to electronics through the “200-in-1” sets that Radio Shack once sold, or even the more recent “Snap Circuits”-style kits. Most of eventually us move beyond these kits to design our circuits; still, there’s something to be said for modular designs. This complete amateur radio transceiver is a great example of that kind of plug and play construction.

The rig is the brainchild of [jmhrvy1947], who set out to build a complete transceiver using mostly eBay-sourced modules. Some custom PCBs are used, but those are simple boards that can be etched and drilled easily. The transceiver is only for continuous-wave (CW) use, which would normally mean you’d need to know Morse, but thanks to some clever modifications to open-source apps like Quisk and FLDigi, Morse can be received and sent directly from the desktop. That will no doubt raise some hackles, but we think it’s a great way to learn code. The rig is QRP, or low power, transmitting only 100 mW with the small power amp shown. Adding eBay modules can jack that up to a full 100 Watts, which also requires adding a 12-volt power supply, switchable low-pass filters, a buck-boost converter, and some bandpass filters for band selection. It ends up looking very experimental, but it works well enough to make contacts.

We really like the approach here, and the fact that the rig can be built in stages. That makes it a perfect project for our $50 Ham series, which just kicked off. Perhaps we’ll be seeing it again soon.

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This SDR Uses A Tube

March 7, 2019 by Al Williams 17 Comments

When you think of a software defined radio (SDR) setup, maybe you imagine an IC or two, maybe feeding a computer. You probably don’t think of a vacuum tube. [Mirko Pavleski] built a one-tube shortwave SDR using some instructions from [Burkhard Kainka] which are in German, but Google Translate is good enough if you want to duplicate his feat. You can see a video of [Mirko’s] creation, below.

The build was an experiment to see if a tube receiver could be stable enough to receive digital shortwave radio broadcasts. To avoid AC line hum, the radio is battery operated and while the original uses an EL95 tube, [Mirko] used an EF80.

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The Cat, The Aircraft, And The Tiny Computer

March 4, 2019 by Jenny List 29 Comments

Sharing your life with a cat is a wonderful and fulfilling experience. Sharing your life with an awake, alert, and bored cat in the early hours when you are trying to sleep, is not. [Simon Aubury] has just this problem, as his cat [Snowy] is woken each morning by a jet passing over. In an attempt to identify the offending aircraft, he’s taken a Raspberry Pi and a software-defined radio, and attempted to isolate it by spotting its ADS-B beacon.

The SDR was the ubiquitous RTL chipset model, and it provided a continuous stream of aircraft data. To process this data he used an Apache Kafka stream processing server into which he also retrieved aircraft identifying data from an online service. Kafka’s SQL interface for interrogating multiple streams allowed him to untangle the mess of ADS-B returns and generate a meaningful feed of aircraft. This in turn was piped into an elasticsearch search engine database, upon which he built a Kibana visualisation.

The result was that any aircraft could be identified at a glance, and potential noise hotspots forecast. Whether all this heavy lifting was worth the end result is for you to decide, however it does provide an interesting introduction to the technologies and software involved. It is however possible to monitor ADS-B traffic considerably more simply.

Thanks [Oleg Anashkin] for the tip.