Category: Other

Raspberry Pi 4 Released: Improvements to CPU, Networking, USB, RAM and more

The Raspberry Pi is the most popular credit sized computing board in the world. It is commonly used as a low cost and portable computing platform for SDRs like the RTL-SDR. Today the Raspberry Pi 4 was released, bringing us a new US$35 single board computer with many improvements. Some of the main improvements that make the Pi 4 great for software defined radios are listed below:

CPU: The Pi 4 uses a Quad-Core Broadcom ARM A72 clocked at 1.5 GHz. This chip should be significantly faster compared to the older chip used on the Pi3B+ with performance now being similar to that of the Tinkerboard. This will be especially useful for CPU intensive SDR applications like the direction finding and passive radar software for our coherent 4-tuner RTL-SDR known as the KerberosSDR. It should also help allow OpenWebRX servers to serve more simultaneous users, allow graphical programs like GQRX to run smoother, and allow for higher sample rates on higher end SDRs.

GPU: The new faster GPU should help graphical SDR programs run smoother.

RAM: The Pi 4 comes with three RAM options, either 1GB, 2GB or 4GB of RAM. The versions with more RAM will be great for memory intensive applications such as GNU Radio (and compiling GNU Radio). It will also allow more programs to run in the background, and perhaps combined with the improved CPU speed allow for multiple SDRs to be used on demanding tasks.

Networking: The Pi 4 finally support Gigabit Ethernet which will be very useful to people using the board as an SDR server over the internet.

USB: There are now two USB 3.0 ports available which means that USB 3.0 SDRs like the LimeSDR could in theory be used at higher sample rates on the Pi 4.

There are also many other improvements such as dual 4K HDMI ports, a USB-C power supply port and faster SD card transfers.

Raspberry Pi 4 Improvements
Raspberry Pi 4 Improvements

It is not yet known if the very useful Raspberry Pi specific software known as RPiTX will continue to function on the new Pi 4. RPiTX is software that turns Raspberry Pi units into fully functional RF transmitters without the need for any additional transmitting hardware - just attach an antenna wire to a GPIO pin. It works by modulating the GPIO pin in such a way to create almost any type of RF transmission. RPiTX only functions on the specific proprietary Broadcom CPU chips that the Raspberry Pi's use. The Pi 4 does continue to use a Broadcom CPU, so we are hopeful.

The new changes bring the Raspberry Pi up to speed with rivals like the Tinkerboard, but at a lower price and with a much better amount of software and OS support provided. The boards currently cost $35 for the 1GB version, $45 for the 2GB version and $55 for the 4GB version. They are sold via local resellers which can be found on the official Pi 4 product page.

The HAARP Project Explained Simply

Over on YouTube Curious Droid has uploaded an interesting video that attempts to explain the purpose of the HAARP transmitter project. The High Frequency Active Auroral Research Program (HAARP) is an ionospheric research program based in Alaska. It consists of a high power transmitter and antenna array which is used to excite a portion of the atmosphere in order to study the ionosphere and investigate methods of affecting radio communications. Recently HAARP was also used in an art project called "Ghosts in the Air Glow" which saw HAARP used to transmit several audio art pieces.

HAARP has also been a popular target of conspiracy theorists who believe that the transmitter must have some sort of sinister purpose. Curious Droid's video explains the purpose and science behind HAARP elegantly, hopefully dispelling any conspiracy theories.

He also explains where some of the conspiracy theories may have originated from. The original idea that HAARP was based on was a patent claiming the ability of Ionospheric heating to disrupt communications, take down missiles & satellites, affect weather, scan the earth and even affect brains. However, a project with such abilities would require ridiculous levels of electrical power and land space for the antennas, making it very unrealistic.

Why is Project HAARP so controversial?

Podcast: The magic of Software Defined Radio with Ben Hilburn

Hanselminutes is a weekly podcast that aims to promote fresh technology and fresh voices to software developers. Last Friday they interviewed Ben Hilburn who is the project lead and president of the GNU Radio Foundation and Director of Engineering at DeepSig Inc who are working on combining deep learning with the signal processing. In the podcast Ben talks briefly about a broad range of topics like spectrum scarcity issues, different SDR hardware, basic SDR fundamental concepts, multipath, GPS, RF security, analogue vs digital and more. It is aimed at technical people who know little about SDR and radio.

EPISODE SUMMARY

Ben Hilburn is the Director of Engineering at DeepSig Inc., which is commercializing the fundamental research behind deep learning applied to wireless communications and signal processing. He also runs GNU Radio, the most widely used open-source signal processing toolkit in the world, serving as Project Lead and President of The GNU Radio Foundation. Ben talks to Scott about why Software Defined Radio is magical and they talk about how SDR can be used to teach STEM and solve interesting engineering problems.

EPISODE NOTES

Ben Hilburn is the Director of Engineering at DeepSig Inc., which is commercializing the fundamental research behind deep learning applied to wireless communications and signal processing. He also runs GNU Radio, the most widely used open-source signal processing toolkit in the world, serving as Project Lead and President of The GNU Radio Foundation. Ben talks to Scott about why Software Defined Radio is magical and they talk about how SDR can be used to teach STEM and solve interesting engineering problems.

Short Article Explaining DSP Basics Without Math

If the math behind software defined radio and digital signal processing (DSP) concepts does your head in, the RSGB has a short document that explains core DSP concepts without any math. If you're just looking for an overview of what terms like sampling, nyquist, aliasing, number of bits, undersampling, digital filters and fast fourier transform mean, then this short article is a great start.

This article, based on a presentation first given at the 2017 RSGB Convention, is intended for the amateur radio exam tutors to help with teaching the new Software Defined Radio (SDR) material in Syllabus 2019. It goes slightly beyond the syllabus requirements and is designed to give a basic background into Digital Signal Processing (DSP), enabling Tutors to answer some questions that trainees may ask, and to help tutors develop their own knowledge. Links to suggested further reading are given for those who might want to know more.

Direct PDF Link: https://rsgb.services/public/exams/presentations/190427_DSP_without_maths_article_v1-3.pdf

[First seen on Southgate Amateur Radio News]

Excerpt of the explanation on sampling
Excerpt of the explanation on sampling

SignalsEverywhere Podcast: Is Software Defined Radio Illegal?

Corrosive from the SignalsEverywhere YouTube channel has released a new episode of his podcast, this time discussing the topic "Is Software Defined Radio Illegal?". Recently we posted about the unfortunate arrest of a UN investigator in Tunisia. Reports from news agencies seem to indicate that a major factor in his arrest was his use of an RTL-SDR dongle for monitoring air traffic as part of his investigation on Libya arms embargo violations. Although it is suspected that other political motivations are at play.

In his podcast Corrosive tries to open a discussion on whether software defined radio (SDR) is illegal, since SDR receivers have the possibility to be able to receive, demodulate and decode almost any signal. He first focuses on mostly American FCC laws regarding scanners, but similar laws are likely to be in place throughout most of the western world. Later in the podcast he discusses transmit capable SDRs and how these are more likely to come to the attention of politicians.

Software Defined Radio Illegal?

Online Course: Software Defined Radio From 0 to 1

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.

The course costs US$37 (currently discounted by 20% to $29.50 via this coupon link) and has a sampling of free videos for you to watch.

A sample slide from Qasim's Lectures
A sample slide from Qasim's Lectures

Elektor SDR Hands-on Book + Arduino Shield HF SDR

Elektor is a popular electronics magazine and hobbyist kit store. Recently they have published a book titled "SDR Hands-on Book" written by Burkhard Kainka. The book is intended as a companion to their Arduino SDR shield kit, which is a low cost module that allows you to turn an Arduino into a 150 kHz to 30 MHz capable SDR. It is based on the G8JCFSDR, which is an RF front end downconverter that allows a PC soundcard to be used as an SDR analog to digital converter.

Kainka's book goes over introductory topics such as shortwave reception, explains signal to noise ratio and interference, different types of antennas, software, digital modes, SDR measurements, receiving and finally WSPR and QRP transmission. If you're interested Jan Buiting also recently reviewed the book on the Elektor website.

Elektor are currently running a promotion and are selling the book + Arduino shield for a reduced price of €49.90.

The Elektor Arduino Shield HF SDR Kit.
The Elektor Arduino Shield HF SDR Kit.

The 2019 New England Workshop for SDR

The New England Workshop on Software Defined Radio (NEWSDR) is a yearly conference that hosts multiple SDR related talks. Previously we posted a selection of our favorite 2018 talks which involved topics such as remote sensing of space with SDR, wireless deep learning and multi-objective SDR optimization.

This years NEWSDR event will been held on Jun 13 and 14 at the University of Massachusetts in Boston. They are currently offering pre-registration for free, and are looking for poster presentations.

This year is the 9th iteration of NEWSDR and it will be held at the University of Massachusetts Boston campus on June 13 and 14. Registration is free and we are also accepting submissions for poster presentations and elevator pitches. The event is an excellent networking opportunity and includes technical presentations as well as demonstrations from industry sponsors (Ettus/NI, MathWorks, Analog Devices, and MediaTek).

NEWSDR 2019 Poster
NEWSDR 2019 Poster