GSoC Student Presentations
The students and some mentors from GNU Radio's participation in the Google Summer of Code in 2012 present their summer work and discuss their experience.
- Sreeraj: gr_filter_design tool
- Luis Esteve: GNSS
- Felix Wunsch: DRM
Embedded GNU Radio and NEON
Philip Balister and Tom Tsou
As embedded and small form factor machines are becoming more popular, there is a growing interest in using GNU Radio at this level. But there are significant issues to address when thinking about these types of machines and their processors, specifically the ARM. Chip speed, memory bandwidth, power considerations are just some of the new things we have to face that make these machines different than our standard Intel/AMD desktops. In this talk , we will give some overview of these considerations and specifically focus on why you need to use NEON, the SIMD extensions for ARM processors.
Afterwards, we will convert this session into a panel discussion, specifically to engage the audience to find out what would make things better for people using GNU Radio on small form factor machines.
USRP Hardware Calibration Tools and Techniques
An introduction to the USRP calibration and correction techniques. In this lecture, we will discuss common RF aberrations that get into the received or transmitted spectrum, and how to correct or work around them with utilities at hand. Specifically, we will look into LO feed through, DC level, and IQ imbalance. USRP tuning techniques and calibration utilities will be explained (and possibly demonstrated).
Building an efficient energy detector with SDR and GNU Radio
During the last few years, much research has been focused on algorithms to improve spectrum sensing. One of these research topics is related to energy detection of signals with low SNR. Most of the research focused on energy detections algorithms is done in simulation tools such as Matlab.
The objective of this work is to build an energy detection block that could be used as a tool in GNU Radio or in GNU Radio Companion. The main characteristic is that the energy detection block gets optimal accuracy when it tries to detect signals with low SNR. It has parameters that could change sensing sensitivity and bandwidth.
Real testing shows that the energy detector block gets excellent accuracy sensing signals with SNR equal to 4 dB with a bandwidth of 5 MHz.
UmTRX - a fully open-source industrial grade SDR transceiver
UmTRX is a wide-band SDR transceiver which could be used in industrial grade applications. It was started as an industry grade hardware for OpenBTS (a GSM base station), but evolved into a universal SDR transceiver. UmTRX is 1GbE based, dual-channel transceiver covering 300MHz-3.8GHz range with up to 28MHz bandwidth. A distinct feature of UmTRX is that it's completely open-source and we hope it will help to spark more innovation and more industry grade open-source hardware projects in SDR area. During the talk I'll go through the technical details, the interesting parts of the UmTRX development history, and show how to use it with GNU Radio and OpenBTS software.
GNU Radio Still in Action
More real-world examples of GNU Radio in use.
The GNU Radio 3.7 API
Explaining the structure and motivation for the new 3.7 API.
tunnel.py: Present and Future
Johnathan Corgan and Josh Blum
GNU Radio ships with an example script known as tunnel.py that enables networking over a digital modulation link. Architected to move data to and from the Linux network stack, tunnel.py is complicated and can be difficult to use. Following on the tutorial about calibrating a USRP, we will take this and better examine how to get tunnel.py to work. With expertise in using tunnel.py in the field and expertise in using USRPs both professionally and in development, we will work to make using tunnel.py easier.
To follow directly on from this, new work is emerging on a different approach to tunnel.py. Although not quite ready for distribution, we will go over the new features and how it enhances the networking over GNU Radio.
BeRadio and beyond - development of the SDRstick UDP Engines
The availability of low-cost FPGA demonstration hardware has made simple, low cost direct-sampling RF-to-UDP engines a reality. The UDPSDR-xxx series of front-ends to the BeRadio SDK offers three cost/performance options for experimenters and developers. The BeRadio's entry-level performance of 12-bits@10MSPS, the UDPSDR-HF1's 14-bit@80MSPS and the UDPSDR-HF2's high-performance firstname.lastname@example.orgMSPS provide hardware front-ends to GnuRadio for a wide range of applications. BeRadio, UDPSDR-HF1 and UDPSDR-HF2 hardware will be covered, as well as BeMicro SDK FPGA code that implements a simple stand-alone MW AM receiver in BeRadio and an openHPSDR-format UDP stream in HF2.
Complete RFID System using GNU Radio
The main components of a Radio Frequency Identification (RFID) system are the reader and tag. To facilitate tests of new functionalities and performance evaluation, previous works use commercial tags and to implement readers and variations of readers using GNU Radio. In this project we extend these works and to implement a tag using GNU radio to obtain a complete software defined radio RFID system. Now it is possible to test new functionalities in the complete system, since it is possible to configure both reader and tag. As an example, the obtained system is used to test security functions using cryptography and multiple antennas. In this presentation we describe the implementation, obtained results and some perspectives of the developed work.
GReasy: GNU Radio Made Easier
Ryan Marlow and Shaver Deyerle
GReasy is an enhanced GNU Radio flow that seamlessly augments the standard GNU Radio framework with modules that reside in FPGAs while preserving GNU Radio dynamics. By delegating portions of a GNU Radio flow graph to networked FPGAs, a larger class of software-defined radios can be implemented. Assembly of the signal processing structures within the FPGAs is accomplished using an enhanced flow where modules are customized, placed, and routed in a fraction of the time required by the vendor tools. With rapid FPGA assembly, a GNU Radio designer retains the ability to perform “what-if” experiments, which in turn enhances productivity.
Future Produce Releases from Ettus Research
Ettus Research QR210 Overview
GNU-radio/USRP-based software-defined radio testbed for distributed beamforming
Muhammad Mahboob Ur Rahman
In this talk, we discuss the key ideas behind our recent all-wireless open-source implementation of distributed beamforming on GNU-radio/USRP-based SDR platform.
Distributed beamforming is a cooperative transmission scheme whereby a number of transmitters in a wireless ad-hoc network organize themselves into a virtual antenna array and focus their transmission in the direction of the intended receiver, potentially achieving orders of magnitude improvements in energy efficiency. Beamforming, however, requires very precise synchronization of the transmitted radio frequency (RF) signals of the cooperating transmitters. In our experiment setup, the receiver periodically broadcasts short feedback packets to all the cooperating transmitters which use a combination of an extended Kalman Filter and a simple 1-bit beamforming algorithm to achieve the RF signal synchronization in a completely distributed fashion.
The relatively large frequency offsets, significant phase noise and drifts in the LOs on the USRPs and large gnuradio/kernel latencies make this synchronization problem particularly challenging. We report some initial results which demonstrate the increase in the received signal strength (RSS) at the receiver due to beamforming. We also discuss directions for future work – our ultimate goal is to develop an open-source library of synchronization primitives to enable the implementation of MIMO techniques in a distributed fashion using the virtual array concept in WiFi, Zigbee and other real-world wireless networks. Finally we discuss opportunities for collaboration between the open-source development and academic research communities to make this goal a reality.
HackRF: A Low Cost Software Radio Platform
The HackRF project is developing an open source design for a low cost Software Defined Radio (SDR) transceiver platform. I will review the project and demonstrate working hardware. I'll discuss the particular design decisions relating to open source hardware development and the intended use as a tool for wireless security research.
Michael Ossmann is a wireless security researcher who makes hardware for hackers. He founded Great Scott Gadgets in an effort to put exciting, new tools into the hands of innovative people.
GNU Radio for Satellite Communications
Skybox Imaging is a satellite imaging startup located in Mountain View, California. During our initial design phase, one of the major decisions made with regards to our Communications system was to use a software-defined-radio architecture for our ground stations' Telemetry, Tracking and Control (TT&C) radios. The motivation for this was twofold: cost and flexibility. Satellite modems typically cost anywhere from a few thousands to tens of thousands of dollars. Moreover, because of our constantly evolving design specifications and need for rapid prototyping and testing, a suitable commercial hardware solution did not exist. The combination of the USRP and GNU Radio proved to be an excellent solution to our problem, allowing us to experiment with many configurations before ultimately settling on our final design.
Our ground station radio system implements an FSK transmitter and two parallel BPSK receivers, operating at different data rates to support the two main operational modes of the satellite we are developing at Skybox. The transmitter incorporates Doppler correction and packet framing. The receivers employ Doppler correction, frequency correction, phase and symbol synchronization, adaptive channel equalization, SNR estimation, Viterbi decoding, BER monitoring, and packet processing. The software-defined-radio system was designed for remote operation and includes a TCP control/monitoring interface as well as a detachable GUI (operating over UDP) for viewing transmitter and receiver parameters, constellations, and spectrum. This presentation will describe the features of our ground station radios and the design flexibility provided by GNU Radio. Additionally, radio performance will be presented along with a demo of our application.
Incorporation of Rate ½ Convolutional Encoder-Decoder into the GNU Radio Benchmark Script
In this project, an uncoded communication system presented in the GNU Radio’s benchmark script is remodeled to incorporate a rate 1⁄2 [171,133] convolution encoder and Viterbi decoder. Also to facilitate packet-based data communication, GNU Radio’s stream tags are adopted. Most of the original python script is replaced using C++ blocks for improved performance. In addition, a signal-to-noise-ratio estimator is employed to obtain some statistics regarding system performances. Final observations show an improvement in the bit error rate and packet error rate.
What's New in GNU Radio & M-PSK Analysis
What's New In GNU Radio
I'll cover a handful of new tools and capabilities that have been instrumented in GNU Radio over the past year, including some up-and-coming features that are actively being developed now.
GNU Radio ships with many different signal processing blocks for digital communications as well as various tools and applications to help visualize, debug, and work with signals. This lecture will walk through the various stages of demodulating an MPSK signal using a live streaming signal to capture over the air. Participants with an available USRP or other receiver can follow along with the live demonstration. Those who will not have access to the over-the-air signal can still follow along using the simulation scripts that can be found under the COST-TERRA Summer School section of my GNU Radio Tutorial page.
Software Defined Radio Direction Finding
Pseudo-doppler radio direction finding (RDF) has traditionally been done in hardware where a timing circuit is used to control the switching of the antenna array, and filter out the pseudo-doppler frequency from the connected audio output of a separate FM radio.
This presentation shows how the same can be achieved in an integrated fashion and with a minimum of hardware (USRP 1 and RF switch IC). The rest of the hardware has been moved into the software domain. The USRP's FPGA code is modified to output a timing signal, synchronised to the captured samples, which controls the antenna switch. GNU Radio is used to perform DSP, which results in a single value: the direction of the transmitter.
This SDRDF concept has been realised as a 'mobile' setup in a vehicle (with array of four antennas on the roof). An additional GUI runs on a second laptop, which receives real-time data via UDP from GNU Radio, to enable track mapping with GPS.
RDF generally has some associated black magic (RF reflections, etc), which also presented itself here since testing was done in an urban area.
Blind signal analysis with GNU Radio
There are quite a few tricks that can be employed when attempting to deconstruct an unknown signal, many of which can be easily implemented using GNU Radio.
I will cover a number of these 'tricks' that would allow someone to peel back the layers step-by-step: modulation type/order, symbol rate, FEC, and then various signal-specific properties (scrambling, identifying structure, guard interval, frame duration, etc). For each I will show the appropriate construction in GRC.
The 'tricks' essentially rely on ideas drawn from cyclostationary analysis and the side-effects of using certain modulations. The main signals I will centre the talk around are those I captured from a geostationary satellite (PSK downlinks), and from HF (OFDM Digital Radio Mondiale, STANAG). The techniques can of course be applied to normal terrestrial signals, too.
Other tools, such as GNU Plot, are also used to visualise the output from the DSP done in GNU Radio.
(The link given relates exclusively to the OFDM work. However the majority of the discussion would be based on the PSK sat signals, which is touched on in the second-half of: http://www.youtube.com/watch?v=Vn-dpUegUDQ)
Aviation Mapper (AvMap)
The USRP can be used to receive Mode S transponder transmissions from modern aircraft. This includes ADS-B signals that broadcast information such as airframe position, speed, altitude, heading, ID, etc. In this implementation, GNU Radio performs the necessary DSP and demodulation of the packets (the decoder is known as 'Modez', and runs as a network server).
Building on top of GR-powered Modez, I have created a complete system ('AvMap') to decode Mode S, as well as ACARS messages (aviation 'text messages'), fuse the two data streams, and visualise local airspace in 3D over the Internet using Google Earth as the live, streaming front-end. The 'virtual cockpit view' uses current track data to re-position the camera so the user can imagine what the pilot is seeing while flying the plane at that moment (best during takeoff and landing). The ACARS messages are represented spatially on the map, and such a visualisation shows how/when certain performance/maintenance/operations messages are exchanged (including unusual ones, such as the state of the on-board lavatories).
With the appropriate antenna and filter, planes have been tracked at a distance of 514 km.
More detailed info/screen-shots can be found at: http://wiki.spench.net/wiki/Modez
(This includes some interesting statistics/graphs that give insight into the performance of the decoder and general aviation flight rules.)
The system is running on pre-recorded replay feed due to relocation of receiver equipment: http://maps.spench.net/aviation/
GNU Radio as a Research and Development Tool for RFID Applications
Radio-frequency Identification (RFID) technology development has experienced tremendous growth over the past decade thanks to organizations such as the US Department of Defense and commercial supply chain logistics. While the traditional use of RFID is for asset management, advances in semiconductor technology have led to lower power and more capable integrated circuits. These advances have led the wireless sensor network (WSN) community to ever increasingly look towards RFID-enabled sensors for their applications. GNU Radio provides a powerful tool for RFID researchers because of its flexibility, DSP block availability, ‘real-time’ data processing ability, and its rapid development time. This talk will focus on the researcher's experience using GNU Radio with a USRP as baseband logic for digital data backscatter from RFID-enabled sensors. GNU Radio paired with the ‘RFID-enabled Sensing Testbed’ (R.E.S.T.), a versatile RFID development platform, has enabled true microwave (5.8 GHz) backscatter application development. Projects to date have included concussion monitoring sensors, temperature sensors, and chemical vapor sensors.
Spectrum Monitoring System and Benchmarking of Mobile Networks Using Open Source Radios - SIMONES. Work in progress.
AbstractThe spectrum management is a complex task of great responsibility, which involves not only the allocation of frequencies and the coordination of these assignments with neighboring countries, but challenges of new uses of spectrum and new technologies, use of spectrum in the long-term, monitoring of the services and adaptation of radio propagation parameters to local conditions. The spectrum monitoring systems are essential tools for these measurements, used to detect possible violations of existing regulations, locate illegal emissions and execute frequency clearance. Mobile operators also use similar systems during the adjustment and deployment of new sites to ensure they are free of interference.
In Latin American countries, there are spectrum-monitoring tasks that differ significantly from other countries, and these specific needs are not usually standard in international systems. This situation, joined with the development of new technologies such as Digital TV and 4G, and the frequency reallocation processes that are running in the region, represents major challenges for these activities and the technologies related to them.
This is why there is a great interest for us to develop simple, unattended operation and low cost monitoring units, to support the monitoring and management tasks and complement the existing monitoring units. To achieve this, it is proposed to use the software radio technology, which combines the flexibility of software radio systems, being able to reconfigure the system according to the tasks and specific monitoring requirements of the region, without changing the hardware components.
Initially, studies on open hardware tools and frameworks for open source radio software where made, allowing us to select the USRP (Universal Software Radio Peripheral) from Ettus Research and GNU Radio as the main tools for the project. With them we have a spectrum analyzer that includes basic features such as scanning frequency bands, the location of peaks and calculation of energy. We are currently working on algorithms for nonionizing radiation calculation, channel occupancy detection and RF measurement, following the ITU standards. We are also working on USRP and user-based drivetest systems to be used for tracking purposes and benchmarking of mobile cellular services like GSM, UMTS and LTE. It will provide measurements in urban areas to characterize telecommunication services in the region.
Upon completion of the project there will be units of Radio Spectrum Monitoring (REM) based on Radio Software and integrated to the TESMonitor Suite, a REM management tool developed by TESAmerica, to offer the industry a low cost product that complements a conventional monitoring system.
Implementation of a DRM+ transmitter in the GNU Radio software radio framework