Recently we came across a company called RFinder / AndroidDMR who are a shop selling custom made two way radios and Android Tablets with built in radio hardware. One of their new tablets that is currently in pre-order is being advertised with a built in RTL-SDR. The preorder status notes that they should be shipping within less than a months time.
The "RFinder Android Radio 10 Inch Tablet - 136-174mhz, 400-490mhz DMR/FM - Embedded RTL-SDR" is able to be pre-ordered for $1,499.95 USD + shipping. It is a ruggedized 10 inch Android tablet with a built in two way 4W VHF/UHF DMR/RF radio as well as an additional built in RTL-SDR. In terms of computing hardware, it comes with an Octa-Core 2.3 GHz CPU, 4GB RAM, 64GB ROM, and it supports cellular connectivity.
In their manual they share the following slide showing the built in RTL-SDR running the RF Analyzer Android app.
Various reviews of the RFinder P10 have been showing up on YouTube. Here is one review by Ham Radio 2.0 where the RFinder P10 is demonstrated at the Huntsville Hamfest.
New RFinder P10 Tablet with Dual Band DMR and RTL-SDR Receiver - Huntsville Hamfest
One part of the amateur radio hobby is 'EME', or Earth-Moon-Earth. The idea is to bounce radio signals off the surface of the moon, and have them received over a vast distance. Typically weak signal amateur radio modulation schemes such as JT65 are used due to their ability to be decoded even with the very weak signals that come back from the moon bounce.
Recently a group of students from the College of New Jersey are attempting to bounce signals off the moon using the LoRa modulation scheme. LoRa is a modulation scheme designed to be used with IoT devices, however it also has great performance when signals are weak so it's a good candidate for moon bounce.
The students are using a HackRF and the SDR-Angel software with the signal being transmitted in the amateur radio bands at 1296 MHz. The antenna hardware consists of an 1296 MHz feedhorn attached to an 8-meter dish. They hope that the use of LoRa modulation can reduce the power requirements for EME.
The main goal of this project is to establish Earth-Moon-Earth communication with LoRa modulated signals. There are three main goals that this project is trying to accomplish. The three goals of our project are to reflect a signal off the Moon and receive it back here in New Jersey, transmit a signal from here in New Jersey, bounce it off of the Moon, and then receive the signal on a dish located in Alaska, and our final goal for this project is to establish two way communication between New Jersey and Alaska.
Our initial approach to this project is to use SDRAngel to modulate and demodulate our signal. SDRAngel is a free, open-source software that we can use to transmit and receive signals via SDR (Software Defined Radio).
Our modulation technique, LoRa, uses Chirp Spread Spectrum modulation that allows for low power, long range transmissions at the cost of a low data rate.
The peripheral of choice for this project is the HackRF One, a SDR peripheral that allows us to send and receive signals.
Thank you to Marc for submitting news of his new project called IQEngine. IQEngine is a free open source web project that allows users to upload IQ recordings of various signals, and share them. The idea is to over time build up a huge database of signals based on IQ data which may be useful for identifying unknown signals, testing decoders and training machine learning databases.
IQ data is essentially the raw radio data from software defined radios before any demodulation or decoding is done. By recording IQ data any demodulation method can be applied to it later. However IQ data does not contain any metadata about the signal itself. To solve this, IQ Engine are using the Signal Metadata Format (SigMF) which allows for information about the IQ recording to be encapsulated along with the IQ recording itself.
The IQEngine web interface includes an easy way to rapidly view and analyze huge IQ recordings, and allows users to annotate them too. At the moment the project is still in the early stages and looking for interested contributors to the FOSS project.
Marc writes:
We're hoping for it to become like a SigIDWiki on steroids, where people can share and learn about different signals using an interactive spectrogram (inspired by Inspectrum), all in the browser so that there's nothing to install. We are putting a lot of emphasis on education and ease-of-use.
There will also be plugins that allow for running signal detection/classification implementations on the signal recordings, to facilitate RFML research, although these plugins could also be used for demod/decoding/etc.
The tool builds off the SigMF standard for metadata, and it works with binary IQ files.
Right now we're mainly looking for more folks to help out with early development, it's really fun working on a FOSS project in the early stages because there are so many design decisions to be made and anyone has potential to step in and make huge contributions and impact the direction the project goes. The code is mostly javascript and python. Anyone interested can join the discord or email [email protected].
IQEngine Display Cellular Downlinks with Annotations
URTI will offer radio amateurs, researchers, educators, and professionals an affordable, compact RF test tool that could be used in place of multiple expensive pieces of traditional radio test equipment.
Our goal for URTI is to design a single hardware platform capable of serving as many popular types of one-port or two-port RF test instruments. We plan to build a directional coupler into a wideband, full-duplex SDR platform to enable URTI to function as a:
spectrum analyzer
vector network analyzer
vector signal generator
vector signal analyzer
antenna analyzer
power meter
frequency counter
full-duplex SDR transceiver
The design and hardware of the URTI appear to still be in the very early stages, with nothing other than early component lab tests released yet. However, given the track record of GSG products, we expect that they will release a high quality and completely open source product in time. We look forward to tracking the progress of the URTI.
Back in 2015 we posted about the dsame software, which is a decoder for the American Emergency Alert System (EAS) which is encoded with the SAME (Specific Area Message Encoding) protocol. EAS transmits on the NOAA weather frequency.
The sirens appear to be activated wirelessly through the same frequencies that weather and EAS use, and so the signal can be monitored with an RTL-SDR or other SDR. When an active signal is present, the forked dsame software will decode the alert. The alert could then be used to activate a local siren or display.
How the SASMEX System Works (Credit: http://www.cires.org.mx/sasmex_n.php)
Recently we came across a new project called DeFli and DeSky, which appears to be plans for a decentralized network of RTL-SDRs. The goal of the project is to provide decentralized access to ADS-B and satellite data through the use of RTL-SDR ground stations. The RTL-SDR ground stations upload their data to the DeFli servers and in return ground station hosts receive compensation in DEFLI tokens via the DeFli blockchain.
From the website it appears they are focusing on selling the data to UAV and satellite operators, but there seems to be no reason why it couldn't be used for other purposes too.
The use of crowd sourced RTL-SDR data is nothing new, with successful ADS-B aggregators like FlightRadar24.com and adsbexchange.com already in operation. Projects like SatNOGs also exist which crowd source satellite data. Not to mention other RTL-SDR and radio data aggregators like marinetraffic.com for Marine AIS, amateur.sondehub.org for Amateur Radio Balloons, aprs.fi for APRS, and airframes.io for ACARS, VDL, HDFL and SATCOM data. However, this is probably the first radio data aggregator to incorporate blockchain concepts for host rewards.
In a Reddit Post (now removed but cached on Google), the creators wrote:
There is clearly an appetite from a large number of Helium Hotspot owners to utilize their hotspots for other projects with a view to getting a better ROI on their investment. That being said, I believe it is absolutely just and fair for Nova & the Foundation to take steps to prohibit the LoRa specific hardware from being used by competing projects both from a commercial perspective and also regulatory. Our personal belief is that Nova/Foundation should operate Helium Network as a NaaS and allow these newer "players" to piggyback on the equipment without compromising the regulatory side of things.
From an industry perspective there is of course a frustration at an awful lot of under-used/under-utilized hardware, specifically the CPU modules that remain in short supply, thus limiting the expansion capabilities of a hardware based network.
Likewise whilst Helium IoT paved the way for decentralized networks to become a "thing" there is also the counter-argument now that actually it is incredibly difficult to build a hardware based network because of the growing disdain. Now obviously part of that is linked to failed projects like MXC, Planetwatch and WeatherXM as well as dubious projects like RevoFi.
That brings me on to our project- DeFli (defli.org). I am not going to extol the virtues of the project, all I am going to give is a very brief "blurb". We are building a decentralized network of ground stations for unmanned aircraft to communicate with (to satisfy new legislation) and which will form the basis of an advanced traffic management system.
A "ground station" can be built from any Helium Hotspot without affecting the performance, nor do we utilize the LoRa Concentrator (ADS-B is broadcast over the 1090MHz frequency). To achieve dual "mining" it is simply a case of running DeFli in a Docker Container (can be viewed on our Github) and adding a USB RTL-SDR receiver.
WARNING: As with anything cryptocurrency related, do your own research first before putting any of your own money in. This project could very well be a scam, or it could just be a project in the early stages of getting started.
On his Medium.com blog, Mohsen Tahmasebi has posted an article about his journey into listening to satellites which started with his acquisition of an RTL-SDR Blog V3 dongle. The article begins by explaining his motivations for receiving satellites and how difficult hobbies like this are to get into in his home country of Iran. Despite the challenges he tasted success when he was able to receive NOAA APT signals on his second attempt using the included portable dipole antenna in a V-dipole configuration. Shortly after Mohsen was also able to receive Meteor-M2 LRPT.
Mohsen then built a more permanent V-dipole out of copper rods and optimized his antenna using NEC simulation software, finding that adding a reflector significantly improved reception. He then moved on to building a slightly more complex Turnstile antenna, which yielded even better results and allowed him to explore CubeSats at 435 MHz and contribute to SatNOGS. Finally, Mohsen ordered a Bullseye LNB and using a homemade bias tee, he received the QO-100 amateur radio transponder.
Overall, Mohsen's journey demonstrates that there is a lot of fun and learning available from internationally available satellites even in a country where equipment is hard to come by.
Mohsen's First Permanent V-Dipole for NOAA APT Reception
Aircraft transmit multiple types of radio signals, including ADS-B and VDL2. ADS-B (Automatic Dependent Surveillance-Broadcast) is an air traffic surveillance technology that enables aircraft to broadcast their GPS position and other data. VDL2 (VHF Data Link Mode 2) is a digital VHF signal, allowing pilots to exchange text information with ground controllers and/or airline ground support. VDL2 is not designed to provide real-time positional data like ADS-B; however, positional information is often broadcast, and the VHF signals can propagate over longer distances.
He also added the "Flight controls on RTL 1090XHSI" software, which allows users to view a simulation of an aircraft cockpit, using real-time ADS-B data from the RTL-SDR.
