Software Defined Radio (SDR) category

Software-defined radio (SDR) is a radio communication system where components that have been traditionally implemented in hardware (e.g. mixers, filters, amplifiers, modulators/demodulators, detectors, etc.) are instead implemented by means of software on a personal computer or embedded system.

Experimenting with software defined radio used to be expensive, but now it is cheap. Nowadays it is very cheap to start experimenting with SDR. Most receivers use a variable-frequency oscillator, mixer, and filter to tune the desired signal to a common intermediate frequency or baseband, where it is then sampled by the analog-to-digital converter. Cheapest wide receiving range well working device is to use suitable DVB-T receiver stick (10-20 Euros/Dollars) and suitable software (very many alternatives, for example SDRsharp and Gnu Radio).

My article Software defined radio with USB DVB-T stick started the long list of SDR related postings. The newest postings now are Filter measurements with RF noise source and Antenna measurements with RF noise source.


  1. Tomi Engdahl says:

    Shmoocon: Delightful Doppler Direction Finding With Software Defined Radio

    When it comes to finding what direction a radio signal is coming from, the best and cheapest way to accomplish the task is usually a Yagi and getting dizzy. There are other methods, and at Shmoocon this last weekend, [Michael Ossmann] and [Schuyler St. Leger] demonstrated pseudo-doppler direction finding using cheap, off-the-shelf software defined radio hardware.

    The hardware for this build is, of course, the HackRF, but this pseudo-doppler requires antenna switching. That means length-matched antennas, and switching antennas without interrupts or other CPU delays. This required an add-on board for the HackRF dubbed the Opera Cake. This board is effectively an eight-input antenna switcher using the state configurable timer found in the LPC43xx found on the HackRF.

  2. Tomi Engdahl says:

    SDR’s Hard Side Shown in DARPA Hackfest

    A DARPA program manager shares experiences from a hackfest he hosted on software-defined radio (SDR) and drones in Silicon Valley last fall.

    When I was running the GNU Radio Project before my current gig at Defense Advanced Research Projects Agency (DARPA) began in 2016, I found it useful to bring the core developers from around the world together for a few days for what we referred to as our “hackfests.” These gatherings gave us an opportunity to break away from our offices and day-to-day responsibilities to work out some of the larger technical problems we were facing in the Project.

    During these few-times-a-year hackfests, we worked crazy-long hours, lived on fast food, and de-prioritized sleep– an energizing combination that fostered collaboration and focused our attentions in uniquely fruitful ways. As a result of some of our hackfests, core and prominent features were created that still reside inside GNU Radio today.

  3. Tomi Engdahl says:

    The XTRX: An Embedded SDR

    Most people getting started with Software Defined Radios (SDRs) will pick up a cheap RTL2832U and R820T2 based RTL-SDR USB stick on Amazon for under $20. There are literally dozens of free and open-source software packages

    The Fairwaves XTRX, now on Crowd Supply, is not one of these sticks. It’s something rather different

    The XTRX is a compact Mini PCIe card SDR based around the Lime Microsystems LMS7002M FPRF. It has 2× 2 MIMO and has a tuning range of 10 MHz — 3.7 GHz, down to 100 kHz with some degradation, with a sample rate of up to 120 MSPS. It has a built-in GPSDO and an onboard FPGA, a Xilinx Artix 7 35T, which can be used to accelerate DSP tasks.

    The XTRX is part of a growing trend right now of productization of maker hardware. We’ve seen this before with things like the Raspberry Pi Compute Module.

    This is an SDR designed to be a component, a black box to be slotted into a bigger build,

    Also available is XTRX PCIe Octopack, a full sized PCIe card loaded with eight XTRX boards, and a special board for synchronising all eight XTRX boards.

    With synchronized clocks, multiple XTRX boards can collectively monitor very large chunks of the RF spectrum—eight synchronised XTRX boards can monitor nearly a full 1 GHz of bandwidth.

  4. Tomi Engdahl says:

    A Classy SDR Chip, Decapped

    If you are a regular searcher for exotic parts among the virtual pages of semiconductor supplies catalogs, you will have probably noticed that for a given function it is most often the part bearing the Analog Devices logo that is the most interesting. It may have more functionality, perhaps it will be of a higher specification, and it will certainly have a much higher price. [Zeptobars] has decapped and analyzed an AD chip that holds all three of those honors, the AD9361 SDR transceiver.

    It’s placed under a slightly inflammatory title, “when microchips are more profitable than drugs“, but does make a good job of answering why a semiconductor device at the very cutting edge of what is possible at the time of release can be so expensive. The AD9361 is an all-in-one SDR transceiver with an astonishing bandwidth, and as such was a particularly special device when it reached the market in 2013.

    The financial analysis puts Analog Devices’s gross profit at about $103 of the $275 retail purchase price of an AD9361. The biggest slice at $105 goes to the distributor, and surprisingly the R&D and manufacturing costs are not as large as you might expect.

    Analog Devices AD9361 – when microchips are more profitable than drugs

    When Analog Devices released their SDR transciever AD9361 in 2013 – it was a revolution in digital radio. SDR’s were there before, but only now you can have it all: 2 channels for TX and RX with onboard 12-bit DAC/ADCs with 56MHz of RF simultanious bandwidth, local oscillators, mixers and LNA – all working in the range from 70 (TX from 47) to 6000Mhz. Using AD9361 out of the box one could implement almost any useful digital radio, with the rare exceptions of UWB and 60GHz. You only need to add data source/sink (which is still often an FPGA), external filters and PA if your task requires it.

    After decapsulation we see 4336×4730 µm 65nm die.

    Let’s do some rough math
    Die size is ~ 21,12mm², 300mm wafer (65nm is only on 300mm ones) has approximately 65’000 mm² of usable area. So given conservative 50% yield we are getting 1538 good dies per wafer. Given wafer cost of 1600$ – manufacturing cost of each good die is ~1.04$.

    NRE – 2 mask sets (400K$ each) and some tooling – will take 1mil$ total. If we conservatively estimate total manufacturing volume of 1000 wafers – NRE would add 0.64$ per good die.

    Retail price of AD9361 at distributes is 275$, volume price from manufacturer is 175$.

    That is quite an impressive added value! For 1,68$ of manufacturing cost we are getting 173,32$ of added value!

  5. Tomi Engdahl says:

    BladeRF 2.0 Micro is Smaller, More Powerful

    When it was launched in 2013, the BladeRF was one of the most powerful of the new generation of Software Defined Radios. Now, Nuand, the producers of the BladeRF are looking to up the ante again with the BladeRF 2.0 Micro. This new version has a huge list of changes and improvements, including a more bad-ass FPGA processor and support for receiving and transmitting from 47 MHz all the way up to 6 GHz, with 2x MIMO support and an impressive 56 Mhz of bandwidth. It also retains backwards compatibility with the original BladeRF, meaning that any software written to support it (which most SDR packages do) will just work with the new device.

    At the heart of the BladeRF 2.0 Micro is an Altera Cyclone V FPGA. Nuand are producing two versions of the Micro: the $480 xA4 uses the 49KLE Cyclone V FPGA, while the $720 XA9 is built around the 301KLE Cyclone V FPGA.

  6. Tomi Engdahl says:

    Using a HackRF One PortaPack as a Mag Stripe Reader and Replayer

    A HackRF One software-defined radio (SDR) will let you zap out and receive radio signals all across the spectrum. Add a PortaPack, and you can do that on the go — for diagnostic tests and white hat hacking only, of course. It’s a handy setup that you can use for all sorts of things, specifically radio things. But, Salvador Mendoza has come up with another interesting use for his PortaPack as a mag stripe reader and “replayer.”

    PortaPack: As FM Mag-stripe Decoder and “Replayer”


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