Software Defined Radio Academy 2015

Programme

Einführung und Überblick

Prof. Dr. Michael Hartje, DK5HH, Programme Committee

Four Generations of SDR Architectures and products

Dr. Howard White, VE3GFW (KY6LA, San Diego DX Club)

In the Past Year, a new 4th Generation SDR Architecture has emerged that not only bests Legacy Radios with better performance but has ergonomic advantages so that Contesters and DXer’s can finally make SDR’s their first choice. The talk will cover the rapidly accelerating pace of evolution of SDR Technology through Four Generations of SDR Architectures with examples of Amateur Radio products using each architecture.

SDR Technology has captured the imagination of Amateur Radio Operators who increasingly chose SDR’s when buying a new radio. This trend has become so dominant in the USA that Legacy Radio Manufacturers have started to mislabel Legacy Radios as SDR’s to try to recapture lost sales from the uninformed. The presentation will define what is an SDR and show where Legacy technology is not an SDR.

There are now Four Generations of SDR Architectures. First Generation SDR Architectures became economically and technologically feasible for amateur radio applications around 2000. Since then the pace of evolution of Amateur Radio SDR Architectures has begun to accelerate rapidly with Second Generation Architectures emerging in 2009, Third Generation Architectures in 2012 and most recently the very exciting Fourth Generation SDR Architectures in 2014. The presentation will define each of these architectures, explain how technological developments have caused them to happen and review the strengths and weaknesses of each architecture.

In order to make the presentation relevant to Amateur Radio Operators, the presentation will include products (with relative pricing where practical) currently on the market that are representative of each of the SDR architectures. Perhaps the most exciting development for amateur radio operators in the past year has been the emergence of a new 4th Generation SDR Architecture that not only bests Legacy Radios with better performance but has ergonomic advantages so that Contesters and DXer’s can finally make SDR’s their first choice.

Praktischer Funkbetrieb mit einem SDR‑Transceiver

Prof. Dr. Harald Gerlach, DL2SAX, Hochschule Neu-Ulm

Nachdem die SDR‑Technik sich im Amateurfunk stetig weiter verbreitet, findet man bei vielen Funkamateuren noch wenig Erfahrung mit dem praktischen Betrieb eines SDR‑Receivers oder SDR‑Transceivers. Bei den zeitgemäßen SDR-Transceivern besteht das Funkgerät aus zwei Komponenten. Die eher unscheinbare Hardware und eine zur gesamten Bedienung notwendigen Software. Für den Funkamateur ändert sich damit das Bedienkonzept fundamental und ist auch gewöhnungsbedürftig, denn die bisherigen „Dreher und Drücker“ sind völlig verschwunden und wurden durch die Maus oder andere Bedienkonsolen ersetzt. Der Vortrag besteht aus einer Demonstration des praktischen Funkbetriebs mithilfe des ZS‑1 und hat zum Ziel die Vorbehalte gegenüber dieser neuartigen Technik und deren Bedienkonzepte zu vermindern.

Entwicklung der SDR Generationen HiQSDR bis R2T2 (DARC WebSDR)

Helmut Göbkes, DB1CC

Based on the fine works of N2ADR we developed an open source SDR called HiQSDR, a full digital DUC/DDC Transceiver wich is used now all over the world by hams.

As a complete new development, a half year ago we started the Project "R2T2", a pure digital SDR transceiver with two independent digital RX and TX channels. This concept allows features like diversity, X-Phase operation, selective predistortion and much more to come.

The R2T2 concept make use of the new XILINX ZYNQ 7020 wich holds not only a big FPGA but also two powerful M9 Arm Cores to allow stand alone operation without external PC. The R2T2 is clocked by a precise, external syncable and free programmable ultra low jitter multi-Clock source up to 800 MHz. Supported by many powerful interfaces like ADC, LCD, HDMI, Audio DSP processors, Gigabit Ethernet and multiple USB connections, the R2T2 is a perfect base for SDR works and: its open source!

Vorverzerrung zur Linearisierung in einem Software Defined Radio Sender – ein Beispiel aus der Praxis mit TRX ZS–1

Prof. Dr. Harald Gerlach, DL2SAX, Hochschule Neu-Ulm

Da analogen Transceiver in den letzten Jahren durch immer leistungsfähigere digitale Signalprozessoren erweitert wurden, konnte es nicht verwundern, dass mehr und mehr TRX-Funktionen mit Hilfe der digitalen Signalverarbeitung vorteilhaft realisiert werden. Während in der ersten Generation von SDR-Systemen noch die A/D-Umsetzung in der NF-Ebene vorgenommen wurde, können heute mit leistungsfähigen, sehr schnell rechnenden „Free Programmable Gate-Arrays“ bereits unmittelbar an der Antenne oder vor der Linear-PA die A/D-Umsetzung vorgenommen werden. Daher soll in diesem Beitrag am Beispiel des Transceivers ZS-1 ein Blick auf die Möglichkeiten einer Sende-Vorverzerrung geworfen werden. Während in analogen Sendern üblicherweise lediglich die ALC (automatic level control) den Ansteuerungspegel der Sendeendstufe unterhalb der Übersteuerung zu halten versuchte, war es nicht mit vertretbarem Aufwand möglich die Verzerrungen des gesamten Signalweges von der Sendesignalaufbereitung bis zur Sendeantenne zu korrigieren. Das Ergebnis ist Kurzwellenamateuren gut bekannt: Splatter und störende Nebenaussendungen. Die vollständig digitale Sendeaufbereitung von Geräten wie dem ZS-1 erlaubt es nun mit geringem Mehraufwand die ausgesendeten Nachbarkanalstörungen durch eine digitale Vorverzerrung nach Amplitude und Phase so zu korrigieren, dass das Sendesignal um mehrere 10 dB geringe Nachbarkanalaussendungen aufweist als konventionelle SSB-Sender – ein starkes Argument für den Übergang zum SDR-TRX. Der Beitrag erklärt das Prinzip und zeigt Ergebnisse am Beispiel des ZS-1

Predistortion for linearization in a Software Defined Radio Transmitters - A practical example with TRX ZS-1

Since analog transceivers have been enhanced in recent years by increasingly powerful digital signal processors, it was no surprise that more and more TRX functions are advantageously realized by means of digital signal processing. While in the first generation of SDR systems A / D conversion has been made at Audio frequency level, with more powerful, very fast computing "Free Programmable Gate Arrays" FPGA already directly at the antenna or in front of the Linear-PA the A / D conversion can be made. Therefore, in this paper on the example of the transceiver ZS-1 the focus is layed on the possibilities of transmitter predistortion. While in analog transmitters usually only the ALC (Automatic Level Control) tried to keep the medium driver level of the transmitter power amplifier below clipping, it was not possible to correct at reasonable cost, the distortion of the entire signal path beginning from the transmission signal generation to the transmitter antenna. The results are well known to shortwave hams: splatters and disturbing spurious emissions. The full digital transmitter processing devices, such as the ZS-1, now allows with a very little internal extra work to correct the emitted adjacent channel interference by a digital predistortion in amplitude and phase so that the transmitted signal shows low adjacent channel transmissions several 10 dB less than conventional SSB transmitters – a strong argument for SDR-TRX. This article explains how it works and displays results on the example of ZS-1

Modernization of Transceiver Application Programming Interfaces (API)

Gerald Youngblood, K5SDR, President and CEO FlexRadio Systems Stephen Hicks, N5AC, VP Engineering, FlexRadio Systems

In the last 30 years, amateur transceivers have continued to advance adding new features and capabilities. The transceiver is, however, only part of the whole station with antennas, filters, amplifiers, switches, loggers, rotators and the like comprising the remainder. Automation of the whole station including the station is important for many kinds of operation including contesting, DXing and remote operation is key for many amateurs. At the center of the automation are the protocols used to control the transceiver. While radios have advanced, the protocols have remained stagnant focused largely on serial communication ports and the CAT protocol. In this paper we explore some of the history of transceiver control and introduce new APIs that provide many benefits over serial protocols such as CAT.

The mcHF SDR and SDR Microwave in Australia

David Minchin, VK5KK, Wireless Institute of Australia (past President VK5)

The first part of the paper will provide a description of the mcHF SDR, an open source HF transceiver project based on hardware and firmware developed by Chris Atanassov (M0NKA). The project was first publicised in late 2013 with hardware being released in April 2014. Development of the firmware has been a collaborative effort with significant contribution from Clint Turner (KA7EOI). The mcHF transceiver is capable of SSB/CW operation on all HF bands from 3.5 MHz to 28 MHz with a nominal output power of 10 Watts. It consists of two main modules, the controlling user interface (UI) PCB and the SDR transceiver (RF) PCB in a compact arrangement. The UI utilises a STM32F407 32 bit CPU for all control functions coupled to a 2.8" colour LCD screen to display frequency, status, etc. The second part of the paper will focus on the author's experiments with the mcHF and other SDR's for microwave portable operations on 2.4 GHz to 76 GHz in Australia The author built his first mcHF UI in May 2014 initially to control a UHF-SDR. A second “complete” mcHF was built in July 2014 to participate in the main development with a third UI now built for firmware testing. Various arrangements have been experimented with using the mcHF with the original RF PCB as well as the UHF-SDR and STM32-SDR controller. The aim is to have a portable “one box” SDR transceiver on 144/432 MHz for operation on both Analog and Digital modes. The desired capability is to integrate digital mode encoding and decoding. For example CODEC2 firmware developed by David Rowe (VK5DGR), PSK31 (STM32-SDR) and JT65 (W1JT)

GNU Radio - Software Defined Radio for the masses

Marcus Müller, ETTUS

In this talk, I'll introduce GNU Radio, the popular free and open source SDR framework and ecosystem. I'll go into how GNU Radio implements the software side of SDR, and explain how it interacts with SDR hardware, demonstrating versatile transceiver implementations using the Ettus USRP B210. We'll have a chance to get a feeling for how building a transmitter or receiver using existing GNU Radio blocks, and how to implement new functionality ourselves.

Anwendungen für den HackRF im Amateurfunkbereich

Gerhard Häring, DK6RH

The HackRF One from Great Scott Gadgets is a Software Defined Radio peripheral capable of transmission or reception of radio signals from 10 MHz to 6 GHz. I will explain the details of the architecture and how to control and program it with GNURadio. In particular, I will demonstrate how to implement a Spectrum Analyzer together wirh a Smartphone, but also how to attach it to a PC and how to build a 2m FM transmitter and receiver.

The Zedboard. The Zedboard: A Modern “System On Chip” for Software Defined Radios

Stefan Scholl, DC9ST, University of Kaiserslautern

Software defined radios can be implemented on general purpose processors like a PC, if the required processing power is low (e.g. if the processed bandwidth is low). A processor offers a high flexibility: It can not only be used to process the data samples, but also to control receiver functions, display a waterfall or run demodulation software. However, if high processing power is required (such as for high bandwidths) processors often do not provide enough processing power. Then the SDR algorithms have to be implemented as custom designed digital circuits on a FPGA (field programmable gate array) microchip. A FPGA provides a very high processing speed, but also lacks flexibility. The circuits is designed for one specific task only and usually it is very difficult to run software on a FPGA. Recently the FPGA manufacturer Xilinx has introduced a hybrid SoC (System on Chip), that combines both approaches. It features a dual ARM Cortex A-9 processor and a FPGA, thus combining the flexibility of a processor with the processing power of a FPGA on a single chip. The Zynq is therefore very interesting for use in SDRs. A widely used development board for the Zynq is the Zedboard (www.zedboard.org). It adds 512 MB DDR3 RAM, an audio codec, HDMI and VGA interface, general purpose IO pins, an FMC connector for daughter boards, USB and Ethernet. A Linux system can be run on the board, making it a standalone embedded computer system, if keyboard, mouse and monitor are connected. In this paper the features of the Zynq SoC and the Zedboard for SDRs will be presented. As an example a direct sampling receiver has been implemented on the Zedboard using a high- speed 16 bit ADC with 250 Msps.

Signals Analytics with Radio Controlled Key Systems

Bastian Blössl, DF1BBL, Distributed Embedded Systems Group, University of Paderborn, Germany

In this talk we will go through the complete process of reverse engineering an unknown digital signal. Although a widespread car key fob from Hella will serve as an example, the aim is to provide a generally applicable walk-through. To decode the signal we will user different tools to determine its frequency, modulation, encoding, and finally its frame format. More specifically, we will use fosphor, baudline, gqrx, and audacity to study the signal in time and frequency domain. Even though we will just have a quick glance at the different applications, the goal is to show they capabilities and more importantly how they can be combined. Once we figured out the waveform and its parameters, we will go ahead an build a receiver in GNU Radio. GNU Radio is a real-time signal processing framework that already provides all means to demodulate the signal and produce a bit stream. At this point we will use command line tools and simple python scripts to study the bit stream to derive the frame format. Finally, we add a small technology specific block to GNU Radio that decodes and parses the frames to build a complete receiver. Hopefully, this will provide some hands-on experience and give an overview over the various tools that are available to study and decode the signals out there.

Radio Data Channel, Reverse Engineered

Andreas Müller, DC1MIL, and Christian Obersteiner, DL1COM, Chaos Computer Club München

Ever wondered how these fancy bus and tram stop signs in public transport get their data? Ever wondered why there are digital signals roaming in the VHF range of your local radio stations? Well, there is a chance that these two things are related to each other! An ETSI standard for wireless infotainment forwarding and teledistribution plus a proprietary system for public transport displays combine to a playground where you can have serious fun! The result is a story about the pleasures of reverse engineering and how easy it is to get knowledge about the signals all around you.

Passive Radar at home

Martin Dudok van Heel, PA1SDR, CEO of Olifantasia.com signal processing solutions

Passive Radar at home, electrosmog made useful - Signal analysis magic with received radio signals and their reflections:

This talk is about using the reflections of FM-radio and GPS satellites signals to do passive radar.

With passive radar you can analyze everything that reflects radiowaves without transmitting anything yourself. The airplanes, cars, buildings, amount of rainfall, the condition of the atmosphere layers, ionized gases, landscape layout, ocean waves, meteorites or individual humans or machines moving inside or outside buildings. Even most stealth airplanes can be detected by passive radar when the signals of distant transmitters are reflected down to the receiving passive radar station.

With the building blocks, normally used for implementing Software Defined Radio Systems you can also do very interesting signal analysis. You can use the opensource toolkits GNU Radio (SDR) + Octave (math) + your own code to analyze the direct path and reflections of any kind of wireless signal. You can use this to do passive radar, which is the art of generating a radar image by analyzing the reflections of signals you have not transmitted yourself. You need to be able to somehow obtain an estimate of the original transmitted signal without reflections, and compare/correlate that to the signal with reflections. Then use the time of arrival, phase, Doppler shift and direction of arrival to determine the exact location, speed and strength of (the source of the) refection, and thus generate a passive radar image.

OpenWebRX, a Multi-User, Web-Based SDR Receiver Application

András Retzler, HA7ILM, University of Technology and Economics, Budapest

Software Defined Radio technology is getting more and more popular among amateur radio operators and hobbyists, as several different universal SDR receiver devices have become available recently. OpenWebRX is a software made for those who want to set up remote SDR receiver stations accessible from the web. It has been developed with open-source codebase, multi-user access and easy setup in mind, to be an alternative to other similar projects (WebSDR, ShinySDR, WebRadio, etc.) It also supports cheap RTL2832U based tuners. Basically, OpenWebRX is an on-line communications receiver for analog modulations (AM/FM/SSB/CW), with a web UI on which real-time waterfall display is available. Users can select a channel within the bandwidth of the sampled signal acquired from the SDR hardware. The selected channel is demodulated on the server and the resulting audio is streamed to the browser of the user, where it is played back. Users can set receiver parameters (channel frequency, modulation mode, filter envelope) independently. OpenWebRX was written in python and JavaScript. The web interface supports multiple browsers and uses modern browser features introduced in HTML5. The digital signal processing functions were placed in a separate library, libcsdr, which has been implemented in C and can also be considered useful as a standalone package. It can perform digital downconversion, filtering and demodulation tasks on I/Q data.

Summary and Outlook

Markus Heller, DL8RDS, Organisation Committee

Published