A Quick Guide to Hardware and GNU Radio
Can't Buy Hardware? No problem!
GNU Radio can be used on its own, without any hardware, as a simulation & development environment. GNU Radio has several blocks that can generate data or read/write files in different formats, such as binary complex values or even WAV-files. A lot of prerecorded examples exist that can be used to develop applications without the need for hardware. If you are looking for a particular waveform to develop with and don't have a capture, ask on the mailing list and someone can likely help!
Additionally, GNU Radio is a powerful tool for hardware simulation. You can simulate complete transmitter and receiver chains, including RF, analog, and other relevant impairments that you would encounter in 'real-world' operation.
Commercially Available SDR Platforms
If you want to use real hardware, you have a number of options. The list of hardware vendors that provide GNU Radio support for their products is growing quickly. Hardware ranges from very expensive measurement-quality systems, to very cheap receiver hardware that you can get for less than $50.
This is not a complete list, but rather provides a rundown of some of the more common options.
''This list is in alphabetical order. Please maintain that order if you add new devices.''
Analog Devices FMCOMMS2/3/4/5 FMC cards + Xilinx Zynq carrier cards.
The Analog Devices boards should not be regarded as stand alone SDR products, but as platforms that are used to either build commercial hardware products, or understand things at the lowest level. If you want to just experiment/use GNURadio, you are better going skipping ignoring these boards, and going to Ettus section. There are commercial systems which are based on Analog Devices's chips, that may be better supported in GNURadio, like the B200 or B210 from Ettus, or the ASRP4 from Agile Solutions.
Analog Devices makes an AD9364 based platform, which is on a evaluation board. The AD9364 is a 1Rx / 1Tx high performance, highly integrated RF Agile Transceiver™. Its programmability and wideband capability make it ideal for a broad range of transceiver applications. The device combines an RF front end with a flexible mixed-signal baseband section and integrated frequency synthesizers, simplifying design-in by providing a configurable digital interface to a processor. The AD9364 operates in the 70 MHz to 6.0 GHz range, covering most licensed and unlicensed bands. Channel bandwidths from less than 200 kHz to 56 MHz are supported.
- AD-FMCOMMS4-EBZ : The AD-FMCOMMS4-EBZ board is a comes specifically tuned and optimized to 2.4 GHz and due to the limitations of the on-board discrete external components (baluns), it may exhibit diminished RF performance on some other programmed configurations.
Analog Devices makes an AD9361 based platform, which is on a few different evaluation boards. The AD9361 chip is ideal for a broad range of MIMO (2Rx, 2Tx)transceiver applications. Otherwise it is identical to the AD9364 (70 MHz to 6.0 GHz tuning range, 200 kHz to 56 MHz RF bandwidth). It can be found on:
- AD-FMCOMMS2-EBZ : The AD-FMCOMMS2-EBZ board is a comes specifically tuned and optimized to 2.4 GHz and due to the limitations of the on-board discrete external components (baluns), it may exhibit diminished RF performance on some other programmed configurations.
- AD-FMCOMMS3-EBZ : The AD-FMCOMMS3-EBZ provides software developers and system architect who want a single platform to operates over a wider tuning range than the AD-FMCOMMS2-EBZ. RF performance expectations of this board must be tempered with the very wide band front end. It does meet the datasheet specifications at 2.4 GHz, but does not over the entire RF tuning range that the board supports. This board is primarily intended for system investigation and bringing up various waveforms from a software team before custom hardware is complete.
- AD-FMCOMMS5-EBZ : The AD-FMCOMMS5-EBZ is a high-speed analog module designed to showcase how to sync two AD9361 in multiple-input, multiple-output (4 Rx, 4 Tx MIMO) applications. The AD-FMCOMMS5-EBZ board has both wideband channels covering the full 6 GHz range, as well as narrowband channels matched to 2.4GHz. The AD-FMCOMMS5-EBZ also contains a calibration matrix between the two AD9361s. This switch matrix hardware, combined with the Analog Devices supplied API software, allow for a full digital and RF synchronization between the two AD9361s.
Those boards do not work by themselves, and do require a some sort of FPGA platform. There are HDL designs for a few different Xilinx carriers : The ZedBoard, Xilinx ZC702, Xilinx ZC706 and Avnet's mini-itx, which are all based on Xilinx's Zynq. All of these use an externally built GNURadio block.
These platforms are built on Linux in kernel drivers using the IIO subsystems, which was reviewed with an SDR usecase at FOSDEM 2015
Ettus Research USRP™ Devices
The Ettus Research USRP™ platform is designed for RF applications from DC to 6 GHz, and provides a wide range of devices. The USRP™ product line spans from affordable hobbyist SDRs to high-end high-bandwidth radios. There are also options for GPS-disciplined synchronization, MIMO configurations, and embedded / headless devices.
For information regarding the USRP™ product line, see the Ettus Research website.
UmTRX is an open hardware dual-channel wideband transceiver that covers 300MHz to 3.8GHz. It includes a TCXO and GPS for frequency stability, and is designed for use with mobile base stations, but can easily be used with many other applications.
Host connection is via gigabit Ethernet and a special version of UHD provides a host driver, along with FPGA and ZPU firmware. An alternate version of the firmware, 4xDDC, can be used to provide double the number of receive signal paths (4), for receive-only applications.
Expansion via mezzanine cards is possible and the UmSEL daughter board can be used for improved performance with GSM use.
The Funcube Dongle is a small and cheap device for narrow band reception, offering a frequency range from 64MHz up to over 1700MHz. It plugs into sound cards, so it could be used with a vanilla GNU Radio, but there are special blocks available on CGRAN.
Great Scott Gadgets HackRF
HackRF One, designed and manufactured by Great Scott Gadgets, is an open source hardware platform for Software Defined Radio. Operating from 1 MHz to 6 GHz, HackRF One is a half-duplex transceiver peripheral with a Hi-Speed USB 2.0 connection. It is bus-powered, portable, and has a maximum quadrature sample rate of 20 Msps. GNU Radio integration is provided via gr-osmosdr.
The Microtelecom Perseus is a USB 2.0-connected receiver targeted for amateur radio SDR, with a frequency range of 10 kHz to 40 MHz and appropriate preselect filters. See http://www.microtelecom.it/perseus/ for more information.
Andrea Montefusco wrote GNU Radio integration that is provided via gr-microtelecom.
Novena + Myriad-RF module
The Novena open hardware computing platform plus the companion Myriad-RF SDR module together provide a system with a quad-core ARM SoC, GPU, FPGA, dual-Ethernet and wideband transceiver that covers from 380MHz to 3.8GHz. This can be used "headless", with a HDMI monitor, or configured as an all-in-one desktop or a laptop with a flat panel display.
BladeRF is a wideband transceiver that covers 300MHz to 3.8GHz, with coverage down to 10MHz made possible with the addition of a block up/down-converter.
Host connection is via USB 3.0 and Nuand support use with Linux, Windows and Mac OS X. GNU Radio integration is provided via gr-osmosdr.
rtl-sdr TV tuners
These are USB dongles based on the Realtek RTL2832 which are designed for DAB/DVB/FM. They can be used as SDR receivers over a frequency range that extends beyond popular television frequencies. Further information is available from osmocom. GNU Radio integration is provided via gr-osmosdr or gr-baz.
SDRplay RSP family of SDR receivers
These are 12/14bit SDRs giving up to 10MHz spectrum visibility from VLF (1kHz) up to 2GHZ with no need for an upconverter. Further information is available from www.sdrplay.com. GNU Radio integration is provided via source blocks developed by HB9FXQ - these are available by following this flow: https://www.sdrplay.com/docs/gr-sdrplay-workflow.pdf
Softrock-like Radio frequency interfaces
Stemming from the amateur radio Softrock (Digital) Direct Conversion devices a family of radio front-ends evolved. The common principle is a direct conversion device that complex mixes the RF signal to base band (a.k.a. audio frequency), using a standard stereo audio interface for input and output. The I and Q channel are mapped to stereo left and right. Advanced devices offer a interface for frequency control and other parameters.
Using your Sound Card with GNU Radio
Most computers nowadays are shipped with a built-in sound interface or sound card. Modern systems universally support input and output with 16 bit resolution at 48 ksps on two channels. Virtually every operating system supports this hardware out of the box, and it's sufficient for a lot of DIY and hobby applications. Additionally, high quality sound interfaces (professional digital audio recording equipment) are available with more than a dozen channels, up to 24bit resolution and 192 ksps.
GNU Radio can use a sound card for both input and output. One way you can use this capability is to create audio interfaces. Do you remember the wonderful screeching and squawking of modems? You could use GNU Radio to experiment with similar communication techniques over audio.
Another way to take advantage of GNU Radio's audio capability is to use a hardware device that converts between audio and RF. Platforms such as SoftRock can be used, in conjunction with GNU Radio and a sound card, to implement a complete radio.
Building your Own Hardware
Several designs are available for electronics enthusiasts interested in assembling their own SDR hardware. Open Source Hardware designs known to work with GNU Radio include:
The comedi project aims to offer drivers for many different data acquisition devices. GNU Radio includes a component that uses this library, which enables GNU Radio to use all devices support by comedi. Comedi is based on Linux kernel drivers, which results in good real time capabilities, but binds comedi to the Linux platform.
The Catch-All Clause
Every device that can be accessed from your operating system can be supported by GNU Radio. You can write your own drivers by creating source and sink blocks for your specific hardware.
A very comprehensive and structured list about Software Defined Radio and Software Radio by Christophe F4DAN can be found at http://f4dan.free.fr/sdr_eng.html
If you cannot find support for your favourite device, ask at the mailing list for help. Maybe someone already got a working solution or wrote a block, or at least you can get tips and encouraging words for building a block for this hardware.