radio

564 Articles

Serious DX: The Deep Space Network

July 21, 2017 by 28 Comments

Humanity has been a spacefaring species for barely sixty years now. In that brief time, we’ve fairly mastered the business of putting objects into orbit around the Earth, and done so with such gusto that a cloud of both useful and useless objects now surrounds us. Communicating with satellites in Earth orbit is almost trivial; your phone is probably listening to at least half a dozen geosynchronous GPS birds right now, and any ham radio operator can chat with the astronauts aboard the ISS with nothing more that a $30 handy-talkie and a homemade antenna.

But once our spacecraft get much beyond geosynchronous orbit, communications get a little dicier. The inverse square law and the limited power budget available to most interplanetary craft exact a toll on how much RF energy can be sent back home. And yet the science of these missions demands a reliable connection with enough bandwidth to both control the spacecraft and to retrieve its precious cargo of data. That requires a powerful radio network with some mighty big ears, but as we’ll see, NASA isn’t the only one listening to what’s happening out in deep space. Continue reading “Serious DX: The Deep Space Network” →

Hackaday Prize Entry: Open Narrowband RF Transceiver

July 14, 2017 by 5 Comments

We have so many options when we wish to add wireless control to our devices, as technology has delivered a stream of inexpensive devices and breakout boards for our experimentation. A few dollars will secure you all your wireless needs, it seems almost whatever your chosen frequency or protocol. There is a problem with this boundless availability though, they can often be rather opaque and leave their users only with what their onboard firmware chooses to present.

The Open Narrowband RF Transceiver from [Samuel Žák] promises deliver something more useful to the experimenter: an RF transceiver for the 868 or 915MHz allocations with full control over all transmission parameters. Transmission characteristics such as frequency, bandwidth, and deviation can be adjusted, and the modulation and encoding schemes can also be brought under full control. Where a conventional module might simply offer on-off keying or frequency shift keying, this module can be programmed to deliver any modulation scheme its chipset is capable of. Spread-spectrum? No problem!

Onboard, the device uses the TI CC1120 transceiver chip, paired with the CC1190 front end and range extender. Overseeing it all is an ST Microelectronics STM32F051 microcontroller, which as you might expect is fully accessible to programmers. Interfaces are either USB, through an FTDI serial chip, or directly via a serial port.

There are a host of transceiver chips on the market which just beg to be exploited, so it is very good indeed to see a board like this one. It’s worth noting though that the CC1120 has a much wider frequency band than that of the CC1190, and with a different front end and PA circuitry, this could cover other allocations including some amateur bands.

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At Last, (Almost) A Cellphone With No Batteries!

July 9, 2017 by 52 Comments

If you are tired of constantly having to worry about the state of the battery in your mobile phone, then maybe help is at hand courtesy of the University of Washington. They are reporting the first-ever battery free cell phone, able to make calls by scavenging ambient power. An impressive achievement, and one about which we’d all like to know more.

On closer examination though, the story is revealed as not quite what it claims to be. It’s still a very impressive achievement, but instead of a cell phone with which you can make calls through the public cell network, it’s more of a remote handset for a custom base station through which it can place Skype calls. Sadly the paper itself is hidden behind a journal publisher’s paywall, so we’re left to poke underneath the research group’s slightly baffling decision to use the word “Cellphone” for something that plainly isn’t, and the university PR department’s dumbing-down for the masses. Aren’t peer reviewers supposed to catch misleading descriptions as well as dodgy science?

In radio terms, it’s an analog AM two-way radio that uses a backscatter transmission technique of applying the modulation as switching to an absorbing antenna tuned to the RF source whose ambient energy is being utilized. This modulates the ambient field within the range of the device, and resulting modulated field can be received and demodulated like any other radio signal. It’s a simplex device, in that you can’t listen and talk at the same time. Other ambient power used by the circuitry is harvested by rectifying received RF and through capturing ambient light on a set of photodiodes. There is a short video explaining the system, which we’ve placed below the break.

Continue reading “At Last, (Almost) A Cellphone With No Batteries!” →

Retro-Styled Raspberry Pi Radio

June 29, 2017 by 5 Comments

Ok, so you want a radio — but not just any radio. It has to be wireless, access a variety of music services, and must have a vintage aesthetic that belies its modern innards. Oh, and a tiny screen that displays album art, because that’s always awesome. This 1938 Emerson AX212-inspired radio delivers.

Building on the backbone of a Raspberry Pi Zero W and an Adafruit MAX 98357 mono amp chip, the crux of this single-speaker radio is the program Mopidy. Mopidy is a music player that enables streaming from multiple services, with the stipulation that you have a premium Spotify account. Once signed up, [Tinkernut] helpfully outlines how to set up Mopidy to run automatically once the Pi boots up. The addition of a screen to display album art adds flair to the design,  and Adafruit’s 1.8″ TFT LCD screen is small enough to fit the bill.

But wait — there’s more!

Continue reading “Retro-Styled Raspberry Pi Radio” →

TEMPEST In A Software Defined Radio

June 25, 2017 by 12 Comments

In 1985, [Wim van Eck] published several technical reports on obtaining information the electromagnetic emissions of computer systems. In one analysis, [van Eck] reliably obtained data from a computer system over hundreds of meters using just a handful of components and a TV set. There were obvious security implications, and now computer systems handling highly classified data are TEMPEST shielded – an NSA specification for protection from this van Eck phreaking.

Methods of van Eck phreaking are as numerous as they are awesome. [Craig Ramsay] at Fox It has demonstrated a new method of this interesting side-channel analysis using readily available hardware (PDF warning) that includes the ubiquitous RTL-SDR USB dongle.

The experimental setup for this research involved implementing AES encryption on two FPGA boards, a SmartFusion 2 SOC and a Xilinx Pynq board. After signaling the board to run its encryption routine, analog measurement was performed on various SDRs, recorded, processed, and each byte of the key recovered.

The results from different tests show the AES key can be extracted reliably in any environment, provided the antenna is in direct contact with the device under test. Using an improvised Faraday cage constructed out of mylar space blankets, the key can be reliably extracted at a distance of 30 centimeters. In an anechoic chamber, the key can be extracted over a distance of one meter. While this is a proof of concept, if this attack requires direct, physical access to the device, the attacker is an idiot for using this method; physical access is root access.

However, this is a novel use of software defined radio. As far as the experiment itself is concerned, the same result could be obtained much more quickly with a more relevant side-channel analysis device. The ChipWhisperer, for example, can extract AES keys using power signal analysis. The ChipWhisperer does require a direct, physical access to a device, but if the alternative doesn’t work beyond one meter that shouldn’t be a problem.

Decoding NRSC-5 With SDR To Get In Your Car

June 21, 2017 by 14 Comments

NRSC-5 is a high-definition radio standard, used primarily in the United States. It allows for digital and analog transmissions to share the original FM bandwidth allocations. Theori are a cybersecurity research startup in the US, and have set out to build a receiver that can capture and decode these signals for research purposes, and documented it online.

Their research began on the NRSC website, where the NRSC-5 standard is documented, however the team notes that the audio compression details are conspicuously missing. They then step through the physical layer, multiplexing layer, and finally the application layer, taking apart the standard piece by piece. This all culminates in the group’s development of an open-source receiver for NRSC-5 that works with RTL-SDR – perhaps the most ubiquitous SDR platform in the world. 

The group’s primary interest in NRSC-5 is its presence in cars as a part of in-car entertainment systems. As NRSC-5 allows data to be transmitted in various formats, the group suspects there may be security implications for vehicles that do not securely process this data — getting inside your car through the entertainment system by sending bad ID3 tags, for instance. We look forward to seeing results of this ongoing research.

[Thanks to Gary McMaster for the tip!]

Hackaday Prize Entry: Sub Gigahertz RF

June 5, 2017 by 10 Comments

For all the press WiFi and Bluetooth-connected Internet of Things toasters get, there’s still a lot of fun to be had below one Gigahertz. For his Hackaday Prize entry, [Adam] is working on an open source, extensible 915 and 433 MHz radio designed for robotics, drones, weather balloons, and all the other fun projects that sub-Gigaherts radio enables.

The design of this radio module is based around the ADF7023 RF transceiver, a very capable and very cheap chip that transmits in the usual ISM bands. The rest of the circuit is an STM32 ARM Cortex M0+, with USB, UART, and SPI connectivity, with support for a battery for those mobile projects.

Of course, you can just go out and buy an ISM radio, but that’s not really the point of this project. [Adam] has come up with an excellent board here, all designed in KiCad, all while flexing his RF muscle. There are RF shields here, too, so it’s far more than just a design challenge, this is an assembly and sourcing problem as well. It’s a great project, and an excellent example of what we’re looking for in The Hackaday Prize.

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