Tagged: rtl2832u

Decoding NOAA on an Debian Chrooted Android Smartphone

Over on Reddit Ian Grody (u/DutchOfBurdock) has posted about his success in using a modded Android smartphone to run an RTL-SDR Blog V3 and NOAA decoder software all within the phone itself.

In the past we posted about Ian's work in getting rtl_power scans to work in conjunction with the Tasker app, in order to generate automated frequency scans on his phone on the go. His more recent work from the past year includes showing us how it's possible to install Debian chroot on an Android phone, and run Linux software like GQRX, GNU Radio, DSD, rtl_433, multimon-ng and dump1090 directly on the phone with an RTL-SDR.

His latest Reddit post shows that the NOAA-APT decoder also runs well on the Debian chroot, leading to a truly portable NOAA decoding setup. He notes that he is now working on the possibility of Meteor M2 decoding on the phone.

Below is his video from last year demonstrating SDR GQRX and GNU Radio running on the Debain chrooted phone.

GQRX, GNU Radio, Rooted Android

Decoding and Logging GPS Coordinates From Wireless Smart Meters

Back in April we posted about "Hash's" RECESSIM YouTube series on hacking electricity smart meters using a software defined radio. Recently his series continues with a video on decoding and logging the GPS coordinates sent by the smart meters used in his area. Using a car, SDR and laptop he was able to drive down the freeway collecting smart meter data as he travelled, decode the data, and plot it on a map. In his video Hash explains why there is GPS data in the signal, and how he was able to reverse engineer and determine the GPS data.

Smart Meter Hacking - Decoding GPS Coordinates

Tech Minds: Remote SDR V2 with Orange Pi and Transmit Capable

In his latest YouTube video Tech Minds explains and demonstrates Remote SDR V2, which is software that allows you to easily remotely access either a PlutoSDR, HackRF or RTL-SDR software defined radio. It is designed to be used with the amateur radio QO-100 satellite, but version 2.0 now include multiple demodulation modes, NBFM/SSB transmission capability, CTCSS and DTMF encoders, modulation compression and a programmable frequency shift for relays.

In his video Tech Minds shows how to install Remote SDR V2 onto an Orange Pi via the SD card image, how to access the web interface, and how to access and use the connected SDR.

Remote SDR V2 with Orange Pi and Transmit Capable

We note that the code is designed to be run on Orange Pi boards, which are low cost single board computers similar to Raspberry Pi's. However over on Twitter @devnulling has indicated that his own fork of the code should run on x86 systems. Aaron @cemaxecuter is also working on including it into a DragonOS release.

The image below demonstrates a typical Remote SDR V2 transceiver setup with two HackRFs.

A full QO-100 Transceiver Setup with Remote SDR V2 and two HackRF's.

European GNU Radio Days: Presentation on gr-rpitx

J.-M Friedt has created a block for GNU Radio called gr-rpitx which allows a Raspberry Pi to be used directly as an output RF sink in GNU Radio. If you were unaware, RPiTX is software that allows you to turn your Raspberry Pi into a transmit capable SDR without any additional hardware apart from a wire antenna connected to a GPIO pin. It works by modulating a GPIO pin in a way to generate any arbitrary signal modulation. gr-rpitx allows this software to be used directly within GNU Radio.

In his presentation uploaded early for the upcoming online European GNU Radio Days conference, J.-M Friedt explains how gr-rpitx works, and shows how you can easily connect any flowgraph to the gr-rpitx output sink. His examples demonstrate retransmitting broadcast FM using an RTL-SDR, broadcasting digital signals like DRM, and how gr-rpitx and RTL-SDR could be used as part of a basic scalar network analyzer.

gr-rpitx uses the GPIO4 output of the Raspberry Pi to generate a radiofrequency stream fed by a GNU Radio signal processing flowchart with sample rates up to 400 kS/s.

European GNU Radio Days/SDRA presentation about gr-rpitx (J.-M Friedt)

Lessons Learned Using SDR in the Classroom

Recently SDR-Boston hosted an online panel titled "Lessons Learned – Using SDR in the Classroom", and the video is now up on YouTube. A presentation was given by three panelists and moderator on the topic of how software defined radio has been used in University curriculum. Many of the courses make use of RTL-SDR dongles, as well as more advanced transmit capable SDRs.

Software-defined radio (SDR) technology is extensively being used across a wide range of research activities to help demonstrate feasibility of new algorithms and approaches that are rapidly defining the new current state-of-the-art in emerging wireless technologies (e.g., 5G/6G, drone networks) as well as providing new opportunities to explore the electromagentic (EM) spectrum world around us (e.g., radio astronomy, satellite communications, radar). Although SDR has become mainstream in research activities, it has not been widely used in the classroom environment to help students leap from theoretical concepts to practical hands-on learning.

The following presentations were given (more information available on the panel website):

1,024 ways to teach with SDR: Dr. Fraida Fund, New York University

Educators who are considering using software defined radio in the classroom face a dizzying array of choices, including hardware, software, and curriculum decisions. In this presentation, I will describe my experiences using software defined radio in different ways for a range of audiences, from high school to graduate school. I will share the decisions I made in designing each course or curriculum module, and the tradeoffs associated with those decisions.

Teaching SDR and DSP to Undergrads within CS: Dr. Marc Lichtman, University of Maryland

Dr. Lichtman will briefly discuss the course he designed and taught at The University of Maryland within the CS dept, introducing students in their senior year to SDR and DSP, as an elective. The first half of the course acts as a DSP and wireless comms primer, essentially condensing several courses that are normally taught at the graduate level within ECE, providing students with the necessary background by teaching DSP theory using diagrams, animations, practical demos, and code examples rather than a mathematically rigorous theoretical approach. The remainder of the course focuses on using SDRs to implement the DSP techniques they had learned. He has recently created a free online textbook based on his course, teaching SDR and DSP with Python, https://pysdr.org.

Teaching Introductory Communication Systems using SDR: Challenges, Benefits, and Lessons Learned: Dr. Cory J. Prust, Milwaukee School of Engineering

Exposure to software-defined radio (SDR) technology is a valuable experience for undergraduate electrical and computer engineering students. Decreasing hardware costs and easy-to-use software tools have made SDR experimentation readily available to the undergraduate laboratory setting. However, especially for students who are still learning the fundamentals of communication systems, laboratory exercises must be carefully designed to reinforce foundational concepts, meaningfully engage and motivate students, and be presented at an appropriate technical level. This presentation will describe the development and deployment of hands-on SDR-based laboratories used in an introductory communication systems course. Lessons learned from multiple offerings of the course will be discussed.

Hands-On Wireless Communications Education: It’s More Than I/Q Representation: Dr. Alexander M. Wyglinski, Worcester Polytechnic Institute

In most undergraduate and graduate courses focusing on digital communication systems engineering, the concept of representing all information in terms of in-phase (I) and quadrature (Q) comes up and becomes the foundation for many other concepts taught throughout the rest of the course. However, the treatment of I/Q tends to be over idealized and the real-world effects affecting this very important source of information is saved “for the next course”. With SDR technology, those real-world effects that are impacting the successful recovery of I/Q samples are experienced right away and the true challenges of digital communication systems engineering are experienced first hand. This introduction will provide some initial insight on the practical considerations when extracting I/Q samples from over-the-air and attempting to decode them for the purposes of recovering binary information.

SDR-Boston Panel Event: "Lessons Learned - Using SDR in the Classroom"

Frugal Radio: A Review of the NooElec Inmarsat Patch Antenna Bundle

In his latest video Rob from Frugal Radio has reviewed the NooElec Inmarsat Patch Antenna Bundle. The US$79.95 bundle includes a PCB patch antenna, Inmarsat SAWBird LNA, SMA DC Block, SMA Barrel adapter and SMA pigtail. In the video Rob tests the bundle out on various AERO signals using the JAERO software, before moving on to compare the bundle with our own RTL-SDR Blog Active L-Band Patch antenna. The comparison results show that our $49.95 L-band antenna is better by about 5-6dB in SNR.

Our RTL-SDR Blog Active L-Band Patch antenna set is available on our store. However, please note that this antenna is currently in short supply due to the global electronics supply chain shortage. We expect to be sold out within a few days but we are aiming to be able to restock within 1-2 months from now.

Review : NooElec L Band Inmarsat Patch Antenna Bundle

A Hi-Z to 50 Ohm Impedance Matching Transformer for Improving HF/SW Reception

Thank you to Mitsunobu for writing in and sharing news about the release of his new product which is a Hi-Z (high impedance) to 50 Ohm matching transformer. This transformer allows you to use small antennas such as short telescopic whips for HF/SW reception on software defined radios.

Generally for HF reception you would want to use a full sized antenna, which can be many meters long and certainly not portable. However, by using an high impedance transformer it becomes possible to use smaller portable antennas. Reception with a small antenna and transformer will still be suboptimal compared to a full sized HF antenna, however, if the signals are strong enough the transformer will allow you to receive them decently.

In the tests shown on his blog (in Japanese, use Google Translate) he shows how the transformer adapter can be connected to a small telescopic whip and Malachite DSP SDR for portable use. Later he also shows how the adapter can make our Dipole Kit antenna work well for HF on a RTL-SDR Blog V3 with direct sampling.  

The product is only available via Amazon in Japan. However, Mitsunobu notes that Amazon.jp offers international shipping. He offers the transformer by itself, and a version including a short telescopic whip antenna.

Hi-Z to 50 Ohm Antenna Transformer for HF/SWL

Frugal Radio: Monitoring HF Aviation Voice Communications with your SDR Radio or a WebSDR

Rob from Frugal Radio has recently uploaded the next episode in his excellent YouTube series on Aviation monitoring. In this episode Rob covers HF aviation communications. Rob writes:

Whether you are using a Software Defined Radio (SDR), an old school HF receiver, or utilizing a WebSDR, there is plenty to monitor when you know where to look.

This video will give you the basics of where to find the Aviation Communications that take place from 3-30 MHz (HF / Shortwave).

This episode covers VOLMET broadcasts, the Major World Air Route Areas (MWARA), and Military Nets like the US Global Communications System (HFGCS).

Remember, these signals travel thousands of miles. It can be quite exciting to receive them over such great distances. When editing this video I was listening to a VOLMET station in Auckland, New Zealand - a distance of over 7500 miles (12,200km) away!

Monitoring HF Aviation Voice Communications with your SDR Radio or a WebSDR