Art Eavesdrops on Life and Pagers

Before cell phones, pagers were the way to communicate on the go. At first, they were almost a status symbol. Eventually, they became the mark of someone who couldn’t or wouldn’t carry a cell phone. However, apparently, there are still some users that clutch their pagers with a death grip, including medical professionals. In an art project called HolyPager, [Brannon Dorsey] intercepted all the pager messages in a city and printed them on a few old-style roll printers. The results were a little surprising. You can check out the video below.

Almost all the pages were medical and many of them had sensitive information. From a technical standpoint, [Brannon’s] page doesn’t shed much light, but an article about the project says that it and other art projects that show the hidden world or radio waves are using our old friend the RTL-SDR dongle.

Pagers use a protocol — POCSAG — that predates our modern (and well-founded) obsession with privacy and security. That isn’t surprising although the idea that private medical data is flying through the air like this is. Decoding POCSAG isn’t hard. GNU Radio, for example, can easily handle the task.

We’ve looked at pager hacking in the past. You can even run your own pager network, but don’t blame us if you get fined.

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Grabbing Better Images From A Newer Russian Satellite

The Soviet Union took the world by surprise when it sent its Sputnik satellite into low earth orbit way back in 1957. The event triggered a space race between the Soviets and the United States and ushered in technologies that would go on to touch the lives of every human on earth. Today, several nations have a space program. And one of the more useful things to put in orbit are weather satellites.

In 2014, the Russians launched their Meteor N M-2 weather satellite into a polar orbit. The part that were most interested in is the fact that it transmits images at 137.1 MHz using the standard LRPT protocol. However, the newer Meteor N M-2 transmits images at twelve times the resolution of US NOAA satellites. No typo there –  that’s twelve (12!) times. Have we got your attention now?

We shouldn’t have to tell you to jump on over to [phasenoise’s] blog which gives you everything you need to start grabbing some of these awesome images.

Now, before you get your jumper wires in a bunch – we are well aware that receiving satellite images is nothing new.

Thanks to [Roy Tremblay] for the tip!



Emergency Cell Tower on a Budget

Cell phone towers are something we miss when we’re out of range, but imagine how we’d miss them if they had been destroyed by disastrous weather. In such emergencies it is more important than ever to call loved ones, and tell them we’re safe. [Matthew May] and [Brendan Harlow] aimed to make their own secure and open-source cellular network antenna for those occasions. It currently supports calling between connected phones, text messaging, and if the base station has a hard-wired internet connection, users can get online.

This was a senior project for a security class, and it seems that the bulk of their work was in following the best practices set by the Center for Internet Security. They adopted a model intended for the Debian 8 operating system which wasn’t a perfect fit. According to Motherboard their work scored an A+, and we agree with the professors on this one.

Last year, the same SDR board, the bladeRF, was featured in a GSM tower hack with a more sinister edge, and of course Hackaday is rife with SDR projects.

Thank you [Alfredo Garza] for the tip.

ColibriNANO USB SDR Receiver Reviewed

At first glance, the ColibriNANO SDR looks like another cheap SDR dongle. But after watching [Mile Kokotov’s] review (see video below), you can see that it was built specifically for software defined radio service. When [Mile] takes the case off, you notice the heavy metal body which you don’t see on the typical cheap dongle. Of course, a low-end RTL-SDR is around $20. The ColibriNANO costs about $300–so you’d hope you get what you pay for.

The frequency range is nominally 10 kHz to 55 MHz, although if you use external filters and preamps you can get to 500 MHz. In addition to a 14-bit 122.88 megasample per second A/D converter, the device sports an Altera MAX10 FPGA.

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The Breadboard RF103

When [ik1xpv] sets out to build a software-defined radio (SDR), he doesn’t fool around. His Breadboard RF103 sports USB 3.0, and 16-bit A/D converter that can sample up to 105 Msps, and can receive from 0 to 1800 MHz. Not bad. Thanks to the USB 3.0 port, all the signal processing occurs in the PC without the limitations of feeding data through a common sound port. You can see the device in action in the video below.

The Cypress FX3 USB device is an ARM processor, but it is only streaming data, not processing it. You can find the slightly modified firmware, a driver for using PC software, and schematics and board layouts on GitHub.

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Testing the Outernet Dreamcatcher SDR

What do you get when you cross an ARM-based Linux PC and an RTL-SDR? Sounds like the start of a joke, but the answer is Outernet’s Dreamcatcher. It is a single PCB with an RTL-SDR software defined radio, an L-band LNA, and an Allwinner A13 processor with 512MB of RAM and a 1 GHz clock speed. The rtl-sdr site recently posted a good review of the $99 board.

We’ll let you read the review for yourself, but the conclusion was that despite some bugs, the board was no more expensive than pulling the parts together separately. On the other hand, if you uses, for example, a Raspberry Pi 3, you might expect more support and more performance.

Despite the L-band hardware, there is a bypass antenna jack that allows you to receive other frequencies. There’s also two SD slots, one to boot from and another for storage. Several pieces of software had trouble running on the somewhat sluggish CPU, although some software that is optimized for the particular processor used fared better. You can read the details in the review.

The board is interesting, although unless you have a special packaging problem, you are probably as well off to combine a Pi and a dongle, as we have seen so many times before. If you have more horsepower you can even make the Pi transmit, although we’d suggest some filtering if you were going to do that for real.

CPLD-Based Synchronization of Multiple Software Defined Radios

Forgive the click bait headline, but the latest work from [Marco Bartolucci] and [José A. del Peral-Rosado] is really great. They’re using multiple HackRFs, synchronized together, with hybrid positioning algorithms to derive more precise localization accuracy. (PDF)

Like all SDRs, the HackRF can be used to solve positioning problems using WIFi, Bluetooth, 3G, 4G, and GNSS. Multiple receivers can also be used, but this requires synchronization for time-based or frequency-based ranging. [Bartolucci] and [Peral-Rosado] present a novel solution for synchronizing these HackRFs using a few convenient ports available on the board, a bit of CPLD hacking, and a GNSS receiver with a 1 pps output.

This is technically two hacks in one, the first being a sort of master and slave setup between two HackRFs. Using the Xilinx XC2C64A CPLD on board the HackRF, [Bartolucci] and [Peral-Rosado] effectively chain two devices together. The synchronization error is below one sampling period, and more than two HackRFs can be chained together with the SYNC_IN port of each connected together in parallel. Read more about it in their pull request to the HackRF codebase.

This simplest technique will not work if the HackRF receivers must be separated, which brings us to the second hack. [Bartolucci] and [Peral-Rosado] present another option in that case: using the 1 pps output of a GNNS receiver for the synchronization pulse. As long as both HackRFs can see the sky, they can act as one. Very cool!