Tackling Trunked Radio With Software

June 16, 2020 by Bryan Cockfield 12 Comments

For those starting to wade into radio as a hobby, one of the first real technical challenges is understanding trunked radio systems. On the surface, it seems straightforward: A control channel allows users to share a section of bandwidth rather than take up one complete channel, allowing for greater usage of the frequency range. In practice though it can be difficult to follow along, but now it’s slightly easier thanks to software defined radio.

This guide comes to us from [AndrewNohawk], who is located in San Francisco and is using his system to monitor police, fire, and EMS activity. These groups typically used trunked radio systems due to the large number of users. For listening in, nothing more than an RTL-SDR setup is needed, and the guide walks us through using this setup to find the control channels, the center frequency, and then identifying the “talk groups” for whichever organization you want to listen in on.

The guide goes into great detail, including lists of software needed to get a system like this started up, and since [AndrewNohawk] is a self-identified “radio noob” the guide is perfectly accessible to people who are new to radio and specifically new to trunked systems like these. Once you get the hang of it, it’s not too hard to scale up, either.

Faking Your Way To USB-C Support On Laptops Without It

March 27, 2020 by Mike Szczys 42 Comments

Is there no end to the dongle problem? We thought the issue was with all of those non-USB-C devices that want to play nicely with the new Macbooks that only have USB-C ports. But what about all those USB-C devices that want to work with legacy equipment?

Now some would say just grab yourself a USB-C to USB-A cable and be done with it. But that defeats the purpose of USB-C which is One-Cable-To-Rule-Them-All^[1]. [Marcel Varallo] decided to keep his 2011 Macbook free of dongles and adapter cables by soldering a USB-C port onto a USB 2.0 footprint on the motherboard.

How is that even possible? The trick is to start with a USB-C to USB 3 adapter. This vintage of Macbook doesn’t have USB 3, but the spec for that protocol maintains backwards compatibility with USB 2. [Marcel] walks through the process of freeing the adapter from its case, slicing off the all-important C portion of it, and locating the proper signals to route to the existing USB port on his motherboard.

[1] Oh my what a statement! As we’ve seen with the Raspberry Pi USB-C debacle, there are actually several different types of USB-C cables which all look pretty much the same on the outside, apart from the cryptic icons molded into the cases of the connectors. But on the bright side, you can plug either end in either orientation so it has that going for it.

Use Your Earbud’s Media Controls On Your Laptop With This Useful Dongle

November 9, 2019 by Gerrit Coetzee 3 Comments

[David] sends in his very nicely designed “Thumpware Media Controller” that lets your mobile phone headphones control the media playback on your PC.

We realize that some PCs have support for the extra pins on cellphone earbuds, but at least some of us have experienced the frustration (however small) of habitually reaching up to touch the media controls on our earbuds only to hear the forlorn click of an inactive-button. This solves that, assuming you’re still holding on to those 3.5mm headphones, at least.

The media controls are intercepted by a PIC16 and a small board splits and interprets the signals into a male 3.5mm and a USB port. What really impressed us is the professional-looking design and enclosure. A lot of care was taken to plan out the wiring, assembly, and strain relief. Overall it’s a pleasure to look at.

All the files are available, so with a bit of soldering, hacking, and careful sanding someone could put together a professional looking dongle for their own set-up.

Software Defined Radio Hack Chat

September 16, 2019 by Dan Maloney 3 Comments

Join us on Wednesday, September 18 at noon Pacific for the Software Defined Radio Hack Chat with Corrosive!

If you’ve been into hobby electronics for even a short time, chances are you’ve got at least one software-defined radio lying around. From the cheap dongles originally intended to watch digital TV on a laptop to the purpose-built transmit-capable radio playgrounds like HackRF, SDR has opened up tons of RF experimentation. Before SDR, every change of band or mode would need new hardware; today, spinning up a new project is as simple as dragging and dropping a few blocks around on a screen, and SDRs that can monitor huge swaths of radio spectrum for the tiniest signal have been a boon to reverse engineers everywhere.

Corrosive is the handle of Harold Giddings, amateur callsign KR0SIV, and he’s gotten into SDR in a big way. Between his blog, his YouTube channel, and his podcast, all flying under the Signals Everywhere banner, he’s got the SDR community covered. Whether it’s satellite communications, aircraft tracking, amateur radio, or even listening in on railway operations, Harold has tried it all, and has a wealth of SDR wisdom to share. Join us as we discuss the state of the SDR ecosystem, which SDR to buy for your application, and even how to transmit with an SDR (hint: you’ll probably want a ham license.)

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, September 18 at 12:00 PM Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

Alarm System Defeated By $2 Wireless Dongle, Nobody Surprised

August 23, 2019 by Dan Maloney 83 Comments

It seems a bit unfair to pile on a product that has already been roundly criticized for its security vulnerabilities. But when that product is a device that is ostensibly deployed to keep one’s family and belongings safe, it’s plenty fair. And when that device is an alarm system that can be defeated by a two-dollar wireless remote, it’s practically a responsibility.

The item in question is the SimpliSafe alarm system, a fully wireless, install-it-yourself system available online and from various big-box retailers. We’ve covered the system’s deeply flawed security model before, whereby SDRs can be used to execute a low-effort replay attack. As simple as that exploit is, it looks positively elegant next to [LockPickingLawyer]’s brute-force attack, which uses a $2 RF remote as a jammer for the 433-MHz wireless signal between sensors and the base unit.

With the remote in close proximity to the system, he demonstrates how easy it would be to open a door or window and enter a property guarded by SimpliSafe without leaving a trace. Yes, a little remote probably won’t jam the system from a distance, but a cheap programmable dual-band transceiver like those offered by Baofeng would certainly do the trick. Not being a licensed amateur operator, [LockPickingLawyer] didn’t test this, but we doubt thieves would have the respect for the law that an officer of the court does.

The bottom line with alarm systems is that you get what you pay for, or sadly, significantly less. Hats off to [LockPickingLawyer] for demonstrating this vulnerability, and for his many other lockpicking videos, which are well worth watching.

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Remote ADS-B Install Listens In On All The Aircraft Transmissions With RTL-SDR Trio, Phones Home On Cellular

August 14, 2019 by Dan Maloney 18 Comments

When installing almost any kind of radio gear, the three factors that matter most are the same as in real estate: location, location, location. An unobstructed location at the highest possible elevation gives the antenna the furthest radio horizon as well as the biggest bang for the installation buck. But remote installations create problems, too, particularly with maintenance, which can be a chore.

So when [tsimota] got a chance to relocate one of his Automatic Dependent Surveillance-Broadcast (ADS-B) receivers to a remote site, he made sure the remote gear was as bulletproof as possible. In a detailed write up with a ton of pictures, [tsimota] shows the impressive amount of effort he put into the build.

The system has a Raspberry Pi 3 with solid-state drive running the ADS-B software, a powered USB hub for three separate RTL-SDR dongles for various aircraft monitoring channels, a remote FlightAware dongle to monitor ADS-B, and both internal and external temperature sensors. Everything is snuggled into a weatherproof case that has filtered ventilation fans to keep things cool, and even sports a magnetic reed tamper switch to let him know if the box is opened. An LTE modem pipes the data back to the Inter, a GSM-controlled outlet allows remote reboots, and a UPS keeps the whole thing running if the power blips atop the 15-m building the system now lives on.

Nobody appreciates a quality remote installation as much as we do, and this is a great example of doing it right. Our only quibble would be the use of a breadboard for the sensors, but in a low-vibration location, it should work fine. If you’ve got the itch to build an ADS-B ground station but don’t want to jump in with both feet quite yet, this beginner’s guide from a few years back is a great place to start.

Non-Nefarious Raspberry Pi Only Looks Like A Hack

November 13, 2018 by Dan Maloney 50 Comments

We’re going to warn you right up front that this is not a hack. Or at least that’s how it turned out after [LiveOverflow] did some digital forensics on a mysterious device found lurking in a college library. The path he took to come to the conclusion that nothing untoward was going on was interesting and informative, though, as is the ultimate purpose of the unknown artifacts.

As [LiveOverflow] tells us in the video below, he came upon a Reddit thread – of which we can now find no trace – describing a bunch of odd-looking devices stashed behind garbage cans, vending machines, and desks in a college library. [LiveOverflow] recognized the posted pictures as Raspberry Pi Zeroes with USB WiFi dongles attached; curiosity piqued, he reached out to the OP and offered to help solve the mystery.

The video below tells the tale of the forensic fun that ensued, including some questionable practices like sticking the device’s SD card into the finder’s PC. What looked very “hackerish” to the finder turned out to be quite innocuous after [LiveOverflow] went down a remote-diagnosis rabbit hole to discern the purpose of these devices. We won’t spoil the reveal, but suffice it to say they’re part of a pretty clever system with an entirely non-nefarious purpose.

We thought this was a fun infosec romp, and instructive on a couple of levels, not least of which is keeping in mind how “civilians” might see gear like this in the wild. Hardware and software that we deal with every day might look threatening to the general public. Maybe the university should spring for some labels describing the gear next time.

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