Back in March we posted about Qasim Chaudhari and his recently released book titled "Wireless Communications From the Ground Up - An SDR Perspective". The book covers advanced University level wireless topics, but he noted how he's attempted to keep the math at school complexity (although for most people we'd say it's still more at undergraduate Engineering school complexity).
Since the last post Qasim has received a lot of feedback from radio amateurs asking for a much simpler introduction to DSP concepts, without the use of University level math. Recently Qasim wrote in and noted how he's now created a set of online lectures that is intended for either professionals who want an overview of physical layer algorithms, or radio hobbyists and general technical persons who want to expand their knowledge.
YouTuber jmhrvy1947, has recently uploaded a number of videos giving an overview of how he built his own HF SDR transceiver using what he calls the “Lego build method”. The idea of the Lego build method was to build a transceiver with parts picked and pulled from eBay so that it could be easily reproduced by others. There are a few scratch made components however those designs are available on his GitHub page. The SDR only functions within about 100 kHz of spectrum at a time however for amateur radio HF work this is more than sufficient. Bare bones the radio puts out a mere 100 mW and although the output power is small, he’s made contacts up to 450 miles away using CW (Morse code). You also have the option of adding an amplifier on your output if you are looking for more power than that. His final revision currently puts out 100 Watts.
Using modified versions of fldigi and Quisk he is able to easily work various digital modes and sync the transmitter and receiver together. The only real down side to this radio is that you must switch out your receive and transmit filters whenever you wish to operate on different bands, a process that really only takes a moment or two.
Check out his videos on the project – it’s really amazing to see what can be done with a small budget these days in radio and with how far software defined concepts have brought us.
DIY SDR CW Xcvr Project
In the video below you’ll see an explanation of the software involved in this build.
His book covers University level wireless communications and digital signal processing (DSP) topics with a focus on SDR. Qasim writes that most DSP books that he's seen in the past were written for professional academics which made them difficult to for other technical (but non-mathematical) persons to understand. You can't explain DSP without equations, but Qasim notes that his book aims to keep the math content at school level only, and with plenty of figures to help with visualization. The description reads:
There are different angles from which this book contributes to the understanding of wireless communication systems from the perspective of a Software Defined Radio (SDR).
In my opinion, any language, including that of mathematics, is an unnatural mode of communication. For example, I can write the words darwaza, porte, puerta, umnyango, ovi and only certain people will understand what I mean. However, if I show you an image of a door, almost every single person on the planet will immediately get the concept. A figure imprints a massive amount of parallel information in our brains that is much easier to process and recall later. Since a human mind handles images very well, I try to visualize equations through beautiful figures which you will encounter throughout the text with logical and intuitive explanations.
If you are not a pure wireless communications academic, you would have found that the mainstream textbooks on this topic are filled with heavy mathematical details which makes this field an exclusive membership club for those who can understand several types of frequency variables and their corresponding Fourier transforms, probability and random processes and detection and estimation theories. While this is true for becoming a master, the Software Defined Radio (SDR) revolution and subsequent projects like GNU Radio have made it possible for anyone to sit down and construct their own unique radio by writing code. Many even do not need to know most of the above mentioned topics. All they need to understand is why an algorithm does what it does so that they know how to write its code, or modify it in an even better way. For this purpose, I have only relied on school level mathematics to explain all the concepts. You will not find any e or j of complex numbers here, nor will you encounter any integrals, probability theory and detection or estimation theory. The only things to know are a sine, cosine and a summation as well as a derivative (which I have occasionally used).
The best books written on implementing digital communication systems using Digital Signal Processing (DSP) algorithms are by fred harris (Multirate signal processing for communication systems) and Michael Rice (Digital communications – A discrete-time approach). As often happens with the grandmasters, they walk on a trail without exactly clarifying it for others. After reading their books, I started to feel that fred harris has mainly focused on `how' of communication systems in an unprecedented detail while Michael Rice has mainly covered `what' of communication systems in his simple and beautiful style. In this process, there were many `why' generated in my mind for which I had to find satisfactory answers. This book is a collection of those simple answers.
An extra little bonus is a one page summary of the crux of Rx algorithms, clarifying the role of particular parameters in the signal waveform. Most of the algorithm design can be understood by just grasping the concepts on this one page.
A common theme in this text is that some concepts seem easier in time domain and some others are simpler in frequency domain, while their mathematical derivations reinforce the idea. It is fun to grasp a concept covering all three sides. Finally, the book contains a few examples from GNU Radio that explain how to set the parameters in some blocks (e.g., Costas loop, band edge FLL, polyphase clock sync, etc.).
The book is currently available on Amazon, and on Amazon you can see a preview of some pages from the book. Qasim also has a website for the book here.
This blog is mostly concerned with software defined radios that are affordable to most hobbyists, but if you've ever wondered what the cutting edge is, take a look at the recently released Per Vices Cyan. This is a US$73,500 one channel RX/TX SDR with a tuning range from 100 kHz up to 18 GHz, ADC resolution of up to 16 bits, a maximum instantaneous bandwidth of up to 1 GHz (with 16 GHz if all channels are required), and an on board Stratix 10 FPGA. There are also higher end Cyan's, with the Cyan Mid having 8 RX/TX channels for USD$149,500, and the Cyan Pro with 16 RX/TX channels for USD$289,000.
Obviously Cyan is aimed at the research, industrial and possibly military market, but maybe this is the sort of capability we will all have in 10-20 years.
Their press release reads:
Per Vices Releases New High Bandwidth, Compact Software Defined Radio Platform
Ontario, Canada- February 20th, 2019
Per Vices, an industry leader in wireless platforms in North America, has been developing Software defined radio (SDR) solutions since 2006, offering customers high performance solutions. Continuing to grow their influence in the wireless communications, radar, signals intelligence, defence, medical imaging, and test and measurement markets. Their newest product, Cyan, is the best SDR available on the market, offering the highest bandwidth on a compact radio platform. Cyan continues to fulfill the company’s legacy by providing the market with the highest performance radio solutions.
Cyan is designed to offer users with a customizable number of independent, phase coherent radio channels, up to 16 total, each offering a standard 1GHz instantaneous RF bandwidth. Featured on a high channel count, ultra wide band, high gain direct conversion quadrature transceiver and signal processing platform. Cyan provides the highest RF and digital bandwidth with an onboard DSP in a compact form factor.
On the digital front, the platform is designed around an Intel Stratix 10 FPGA SoC enabling significant DSP resources for a variety of applications. The platform also features 4 x 40 Gbps digital backhaul enabling ultra-high data throughput while maintaining low latency for applications that require raw radio data to be transferred to another platform.
To learn more about Cyan, Per Vices, or their other product offerings, contact Brandon Malatest at +1 (647) 534-9007, or email [email protected], or visit the website at www.pervices.com
Recently, the RF research team at Trend Micro released a very nice illustrated report, technical paper and several videos demonstrating how they were able to take control of building cranes, excavators, scrapers and other large industrial machines with a simple bladeRF software defined radio. Trend Micro is a well known security company mostly known for their computer antivirus products.
Trend write that the main problem stems from the fact that these large industrial machines tend to rely on proprietary RF protocols, instead of utilizing modern standard secure protocols. It turns out that many of the proprietary RF commands used to control these machines have little to no security in place.
Five different kinds of attack were tested. They included: a replay attack, command injection, e-stop abuse, malicious re-pairing and malicious reprogramming. The replay attack sees the attackers simply record commands and send them again when they want. Command injection sees the hacker intercept and modify a command. E-stop abuse brings about an emergency stop, while malicious re-pairing sees a cloned controller take over the functions of the legitimate one. And malicious reprogramming places a permanent vulnerability at the heart of the controller so it can always be manipulated.
So straightforward were the first four types of attack, they could be carried out within minutes on a construction site and with minimal cost. The hackers only required PCs, the (free) code and RF equipment costing anywhere between $100 and $500. To deal with some of the idiosyncracies of the building site tech, they developed their own bespoke hardware and software to streamline the attacks, called RFQuack.
Being a responsible security firm, Trend Micro has already notified manufacturers of these vulnerabilities, and government level advisories (1, 2) and patches have already been rolled out over the last year. However the Forbes article states that some vulnerabilities still remain unpatched to this day. Of interest, the Forbes articles writes that for some of these vendors the simple idea of patching their system was completely new to them, with the firmware version for some controllers still reading 0.00A.
The videos showing the team taking control of a model crane, real crane and excavator are shown below. The video shows them using bladeRF 2.0 SDRs which are relatively low cost TX/RX capable software defined radios. We also recommend taking a look at Trends web article as it very nicely illustrates several different RF attack vectors which could apply to a number of different RF devices.
The idea behind the article is to introduce people to SDR from a shortwave listening point of view, so high performance HF SDRs like the Airspy HF+, Elad FDM-S2 and WinRadio Excalibur are discussed. Thomas notes that these SDRs can perform as well as traditional DX-grade receivers that can cost two to three times more. He also explains what advantages SDR's bring to the shortwave radio listening hobby. This may be a good article to show those still using older hardware radios that haven't yet converted to the SDR world.
The article is currently part one of a three part series, with parts two and three to be released in October and November.
Helium is a cryptocurrency being designed for internet of things (IoT) sensors which will be based on low cost software defined radio (SDR) technology - that's a lot of buzzwords!. The idea is to design a system that will pay people to run an internet connected gateway which will receive data from wireless sensors, and put that data onto the internet. A use case that Helium has already developed is providing services to track and monitor medicine and food supplies. The linked article gives a good example of this use case:
...let’s say you have a gateway in your house: if a vial of medicine were to enter your coverage zone, it would send its location and temperature data to your gateway, which would then send it to its proper destination in return for a previously agreed upon cryptocurrency fee. These steps would then be cryptographically verified and recorded in the distributed ledger.
In terms of IoT network competition, LoraWan and SigFox IoT networks are already popular and established in several places in the world, but wireless coverage isn't great because these networks rely on companies to build gateway infrastructure. Helium crowd sources this infrastructure instead, which could result in greater coverage.
Most cryptocurrencies base the security of their network on the 'proof of work' process, which is a way to ensure that the miners get rewarded for the heavy cryptographic computations that they do in order to secure the network. Instead of proof of work, Heliums idea is to use a 'proof of coverage' system, where other gateways will confirm if a gateway is providing coverage and is in the correct location. Helium cryptocurrency 'miners' will be the people running the internet connected gateways, and they will be paid for any devices that use their wireless coverage.
According to one of their latest blog posts, the wireless gateway radio system is to be based on a software defined radio architecture. The reasoning behind using SDR is that they need to support potentially thousands of wireless sensor channels, require the sensors to be able to be geolocated, and require the radio to be low cost and energy efficient. For geolocation of sensors they are considering the use of radio direction finding techniques that we assume will be based on pseudo-doppler, or alternatively they will use the time difference of arrival (TDoA) technique which requires the signal to be received by multiple gateways. The SDR will be developed on a dual core TI SoC, with four programmable realtime units (PRU), which they'll use to interface with the RF chips.
At the moment Helium is just a whitepaper, and we haven't seen any concrete evidence of a working SDR design yet, but according to their website they plan to launch gateway hardware in Q4 2018 for a cost of $495.
The New England Workshop on Software Defined Radio (NEWSDR) was held in May this year, and there have been several talks now uploaded to YouTube. These are typically fairly technical in nature, and discuss cutting edge research being performed with software defined radios. Below we post a few selected talks, and the rest can be viewed in this WPI playlist.
Remote Sensing of the Space Environment Using Software Defined Radio
From studies of the ionosphere to astronomical measurements with arrays of radio telescopes the manipulation and analysis of RF signals has been key to new instrumentation and many resulting discoveries. Software radio technology has been a core component of remote sensing of the space environment for several decades now. The flexibility of combining computing and radio was adopted very early on in scientific applications. This enabled new classes of scientific experiments which would otherwise have been impossible. The capability and adaptability of software radio instrumentation and systems has been growing consistently with the exponential increase in available computing power. The recent surge of low cost software radio hardware technology has enabled a new generation of instrumentation. These instruments are increasingly blurring the line between traditionally separate scientific disciplines as well as practical applications. I will discuss the science and the instrumentation enabled by software radio with highlights from studies of the ionosphere and radio astronomy. My overview will focus on the relationship to work underway at MIT Haystack Observatory. I will highlight the core architectural patterns of scientific software radio and discuss the evolution of our systems over several decades of rapid technological change. I will also look forward to the possibilities for discovery offered by the next generation of software radio and radar instrumentation.
NEWSDR 2018: Invited Presentation by Frank Lind (MIT Haystack)
Reinventing Wireless with Deep Learning
While wireless communications technology has advanced considerably since its invention in the 1890s, the fundamental design methodology has remained unchanged throughout its history – expert engineers hand-designing radio systems for specific applications. Deep learning enables a new, radically different approach, where systems are learned from wireless channel data. This talk will provide a high-level overview of deep learning applied to wireless communications, discuss the current state of the technology and research, and present a vision for the future of wireless engineering using a data-centric approach.
NEWSDR 2018: Invited Presentation by Nathan West (DeepSig)
Multi-objective SDR Optimization for Wireless Access, Actuation and Attacks
Software defined radios (SDRs) have become the foundational block of agile wireless communications. The first part of the talk presents an overview of how the same SDR can alternate between multiple different and non-traditional actuation functions, such as aerial distributed beamforming and wireless energy transfer. Furthermore, as SDR technology becomes more pervasive assuming roles beyond communication, there is a growing risk of security concerns of ID spoofing and malicious hardware attacks. The second part of this talk describes our efforts of fingerprinting individual SDRs using machine learning, where we only analyze the I/Q samples collected at the receiver. We demonstrate the feasibility of achieving 90-95% classification accuracy through experiments conducted with 12 radios, at separation distances of beyond 50 feet. The talk concludes with a summary of the challenges ahead and identifies other emerging application areas of SDRs that will impact the next decade.
NEWSDR 2018: Invited Presentation by Kaushik Chowdhury (Northeastern University)