Over on YouTube Ian Grody has uploaded two videos demonstrating an early alpha project that he is working on which combines Android Tasker with RTL-SDR frequency scanning. Tasker is an Android automation app which allows users to define a task based on a context. For example, you could set it to turn on WiFi and open an app (task) every time you arrive at a certain location (context).
Ian's idea is to create a Tasker application that performs an rtl_power scan with the RTL-SDR whenever a certain context is detected. The current version of his Tasker app can perform an rtl_power scan over a certain frequency range at the tap of a button, detect the strongest frequencies in that range, and plot a marker at the current location on a Google map which displays the strongest frequency detected at that location. He eventually hopes to turn the application into a wardriving application that will scan 27 MHz - 1.7 GHz for active signals while on the move.
Thank you to Agrosi Luciano for submitting news about his new RTL-SDR compatible Android App called "IGate2". IGate2 is a receive only APRS IGate written for Android devices. There is a free and paid version of the app. The free version is limited to 100 packets forwarded per session. The paid version costs US$3.49 and has unlimited packet forwards. The description of the app is pasted below:
The RTL-SDR dongle tuner (cost starting from 10 €) and its antenna, receives the information contained in APRS packets transmitted from HAM radio stations, and then a phone device, with IGate2, forwards them to the world wide web using its internet connection (WiFi or 3G).
IGate2 acts as a Software Defined Radio Demodulator, a TNC Modem and an Internet Gate.
If you already own an unused cellular phone or tablet, IGate2 represents a very cheap, compact and easy-to-use solution for suppling an IGATE service to radio amateur community.
Raw data contained in radio packets are visible on the phone screen and may be routed (if you check this option) to the APRS-IS network. All data convoyed and shared in APRS-IS network can be seen in maps and bulletins on particular websites, for example: http://aprs.fi/ .
To be authorized to send data to APRS-IS you must have a HAM CallSign and a PassCode. See aprs-is.net. If you are not a radio amateur, you may only use your equipment in receive only mode. The app has an audio monitor useful for tuning the parameters of the Sdr receiver (it may not work well in old devices with low memory). In the main page there is a frequency switch, a hub with the text of received packets, two indicator lights: one for the Sdr connection and one for the Aprs-Is connection, three counters reporting the number of: received, forwardable and forwarded packets. When you leave the main page while the IGate is running, the app service will continue working in the background, you can recall the main page by tapping the service icon in the android status bar.
Since the device and the Sdr dongle drains much power from the phone battery, it is recommended to use the phone charger or a power bank. You will need an OTG power cable. It is not easy to find a working cable, maybe you can do it yourself. The reception quality of the IGate depends, above all, on the antenna connected to the Sdr dongle. With very strong FM broadcasts in your area, it may be helpful to manually adjust the gain of the receiver or use a band-stop filter.
If you weren't already aware, Automatic Packet Reporting System (APRS) is a digital VHF mode used in amateur radio. It allows for packets of data to be sent to receiving nodes over a local area via RF. Typical uses for it are vehicle tracking, weather station telemetry, text messages, announcements and other wireless device telemetry like high altitude balloons. An IGate is an internet connected node which receives local APRS RF signals and uploads them to the internet, to be seen on sites like aprs.fi. TX capable IGates may also broadcast to the local RF network messages from APRS transmitters on the other side of the world.
IGate2: Android App that turns your phone and RTL-SDR into an APRS IGate.
Over on onesdr.com a new SDR tutorial website, the authors have put up three new posts. The first post is part 2 of their "How Not to Break your Software-defined Radio (SDR) Hardware" series. This post covers mechanical strain considerations on connectors and reference clock input voltages.
The second post titled "Software-defined Radios and Bias Tees" covers the use of bias tee's and the different voltage and current specs of bias tee's on different SDRs. They explain how these specs affect which LNA's you can use, and how some bias tee's are protected against over-current damage.
ADSBExchange is an aircraft tracking website service which aggregates ADS-B data from contributors running RTL-SDR's or similar receivers worldwide.
However, unlike other flight tracking sites such as flightaware and flightradar24, ADSBExchange sets themselves apart by proudly refusing to censor the tracking of military and private jets that have requested privacy. One area where this refusal to self-censor helps is with the "Dictator Alert" service. This is a service that automatically tracks the movements of private aircraft owned by authoritarian regimes via the ADS-B data collected and shared by ADSBExchange.
Recently ADSBExchange upgraded their web interface moving from the old Virtual Radar Server system to tar1090 which is a more fully featured open source display for dump1090. This new interface has some great features, like the ability to view the complete flight track history of any aircraft on a particular day, the ability to display only military aircraft and the ability to filter by altitude and aircraft type.
ADSBExchange.com new tar1090 interfaceViewing the historic tracks of 1-day of police helicopter activity in the new ADSBExchange tar1090 interface.
Back in early January we posted about how the popular web based SDR and RTL-SDR compatible receiver software known as OpenWebRX was officially discontinued by the original author. However, thanks to it's open source licence, code contributor Jakob Ketterl (DD5JFK) has been able to continue developing the code and is taking over as the lead developer on his own fork of the code.
Recently he released version 0.18.0 of OpenWebRX which includes a few major upgrades including the much needed shift to Python 3, and the inclusion of multiple new decoders for DMR, D-Star, YSF, NXDN, FT8, FT4, WSPR, JT65, JT9, APRS and Pocsag.
Hello fellow radio enthusiasts,
with great excitement I would like to announce the availability of OpenWebRX Version 0.18.0 as public release. This is the first release of the project in some time, and the first release since I started working on it, so I’m more than happy to bring this to you.
What’s new? Quite a lot, actually. For those that haven’t had the chance to follow the progress of the project in the past months, here’s a quick overview:
Most of the server code has been rewritten for better flexibility, stability and performance. The project is now fully based on Python 3.
Large parts of the frontend code have been updated or polished.
The new core now supports multiple SDR devices simultaneously, as well as switching between multiple profiles per SDR, allowing users to navigate between multiple bands or frequencies.
Added support for demodulation of digital voice modes (DMR, D-Star, YSF, NXDN).
Added support for digital modes of the WSJT-X suite (FT8, FT4, WSPR, JT65, JT9).
Added support for APRS.
Added support for Pocsag.
Bookmarks allow easy navigation between known stations.
Background decoding can transform your receiver into an automatic reporting station, including automatic band scheduling.
The integrated map shows digimode spots as well as APRS and YSF positions.
OpenWebRX 0.18.0 is available via the following channels:
Please check out our updated Setup Guide along with the rest of the documentation on the Wiki!
Questions, ideas, problems? Get in touch with the community at [email protected]!
Best regards and vy 73s
Jakob DD5JFK
We're so glad to see that this excellent software isn't dead in the water and is in fact thriving. We will continue to follow the Jakob's and the OpenWebRX communities' future developments. If you are interested, you can follow OpenWebRX development on the OpenWebRX groups.io forum.
If you've been following KerberosSDR development (our US$149 4 channel coherent RTL-SDR), then you'll know that one interesting experiment that you can set up with it is a passive radar. Passive radar makes use of already exiting strong transmitters that broadcast signals such as FM, DAB and HDTV.
With one directional antenna pointing towards the transmitter, and one pointing in the general direction of moving objects like aircraft, it's possible to detect the transmitted signal being reflected off the aircraft's body.From the time delay and doppler shift detected in the reflected signal, a simple distance/speed plot showing the aircraft in motion can be created. This previous post shows an example of what information you could potentially collect in a range/speed graph over time. In the past we've also used passive radar to detect vehicles and measure how much traffic is in a neighbourhood.
However, with two antennas we can only get the detected object's range and distance information. If we use four antennas (one pointing towards the transmitter, and three pointing in the direction of objects), it is possible to use beam forming techniques combined to obtain an estimated map coordinate of the object. This is possible as we then we have distance information available from the passive radar algorithm, and bearing information available from the beam forming algorithm.
Tamas Peto who wrote our open source KerberosSDR code has been working on some new upcoming features for the KerberosSDR software, and beamformed direction finding of passive radar is one of them. We note that to be clear this software is not yet released, and we still expect there to be several months before it is ready. At the moment all data was processed manually offline after collecting data with a KerberosSDR as part of this early test.
The image below shows an example of a recent measurement made from an aircraft. The red tracks show the actual ADS-B GPS coordinates of the aircraft, and the black line indicates the positional data measured from a DAB signal reflecting off the aircraft body. The orange line to the east indicates the main lobe of the three beam formed directional antennas, and the lines to the west indicate transmit towers.
The measured trajectory is only about 1-2 km off the actual one. Tamas notes that the position offset may be because at the moment altitude is not measured yet.
If you're interested in more information, Tamas created a PowerPoint presentation which can be downloaded from our Google Drive.
Passive Radar with Beamforming and Direction Finding
Other upcoming features that are planned for the KebrerosSDR code include being able to use direction finding on short bursty signals, improvements to networked direction finding and beamforming which may be useful for applications like radio astronomy and performance improvements.
KerberosSDR can be purchased from the Othernet store or Hacker Warehouse, and every purchase helps us fund development of more interesting features like passive radar beamforming!
The Mission for Education and Multimedia Engagement Satellite (MEMESat-1) is planned to be the first meme broadcasting cube satellite ever created. If you aren't down with modern slang and are not familiar with the word "meme", that may be because although first coined in 1976, the modern definition was only added to the Webster-Miriam dictionary in 2015. In the traditional sense a meme is a cultural idea, behavior, style that people can't help but want to share because of how funny/amusing/interesting it is.
But in particular MEMESat-1 wants to broadcast from space the new type of meme definition, which is essentially funny or amusing images/GIFs that internet users and especially youth like to modify and share online through social media. Memes have become a major part of internet youth culture, so this could be an excellent way to speak the language of the next generation and get them interested in space, satellites, amateur radio and building satellite ground stations.
At the moment, the team hopes to launch the satellite by late 2021, and no later than Spring 2022. The satellite will be a cubesat with flash memory containing thousands of meme images that will be broadcast to Earth via a transmitter operating in the UHF 70cm radio band. Enthusiasts on the ground will be able to receive the meme images with a Yagi antenna and we anticipate that RTL-SDRs will be a commonly used receiver. The satellite will also contain an FM UHF/VHF repeater operating in the amateur radio band for ham radio use.
I went out and started a nonprofit organization, built a website, developed a meme-related anxiety disorder, and am now building a meme-beaming satellite with a group of undergrads at UGA and some industry sponsors. And it’s all for the sake of making a novel meme. We are now fundraising to launch MEMESat-1.
For those who are interested in reading about the trials and tribulations of a 22 year old man-child trying to send memes into space, I’ve included the longer story below.
For my whole university career, I was in search of different work opportunities and internships to see what felt the most fulfilling and to get some of those sweet sweet resume lines. I’ve interned at a plastic factory, the Air Force Research Labs, NASA JPL, and Ball Aerospace. They were all great places filled with awesome people and cool work, but I didn’t feel connected with my work in a way that fulfilled me. So, for the past 3 years me and my buddies have been joking around about building a satellite that beams down memes from space.
Enter MEMESat-1.
While I was working at JPL, me and some buddies got together to toy around with space start-up ideas. We joked more about MEMESat, and bought the memesat.com domain back in 2018. Due to timing and other life events the start-up idea kind of fell off. One of my pals is pursuing his Ph.D, and the other is working as a spacecraft engineer full-time. I on the other hand, still had 2.5 years of school left.
Work on the MEMESat concept slowly came to a halt by the end of 2018, but picked up again in Spring 2019 when I came up with the acronym the Mission for Education and Multimedia Engagement Satellite (MEMESat-1). I kept telling my classmates and friends about the project idea as a joke, but they thought I was being serious and told me to go for it. By May 2019 I had worked out a deal with some universities to use their space, and began building the website. Over that summer, my job left me some spare time, so I started ramping up the social media for MEMESat-1 by posting daily spacefacts to instagram. I also worked on some preliminary design studies to see if the mission would be feasible, and decided that it definitely was. I also spent the summer researching how to form a company, and what the best company structure would be.
In August 2019, I returned to school and began to work on forming a company. Some great profs at GT gave me the advice to start a nonprofit, so I searched for some pro bono legal advice on starting a nonprofit. I took some of the lawyer’s advice and found some willing Directors for the company, and filed to form a nonprofit corporation - called Let’s Go to Space, Inc.
Around that time, I posted to reddit and got a bunch of attention from you guys, so I figured I should work my hardest to make it happen. I spent months emailing every space related company I could find or even think of. I have much more respect now for people that lead telemarketing campaigns, because it is really hard to convince random people over the phone/email to give you large sums of money. Now, I am happily partnered with Ball Aerospace and sponsored by Blue Canyon Technologies. I’m also in talks with some launch providers about a free launch and some help launching my lesson plans/experiment kits to classrooms all over!
We have passed the point of no return and have nowhere to go but upwards. My parents are confused and slightly disappointed that their rocket scientist son has given up any sort of salary in an effort to appease his ‘internet friends’. God bless you magnificent weirdos for keeping me going. Ad Astra Per Memes.
Currently letsgo2space is fundraising and looking for $30,000 to fund the launch of MEMESAT-1. You can either donate any amount or submit a meme for their broadcast database for $1.69 via their website.
Thank you to Benjamin Larsson for submitting news about a FC0013 tuner patch he's submitted for the Osmocom RTL-SDR driver code. FC0013 based RTL-SDRs have been relatively unpopular due to the reduced tuning range of only 22 - 1100 MHz, compared to the larger 24 - 1766 Mhz range provided by the R820T2 chip. However, they have been found in some cheaper units.
Benjamin's patch reportedly improves UHF performance above 862 MHz, and also seems to make ADS-B reception usable.
The patch was submitted to the Osmocom GitHub, however, this Git is not monitored as Osmocom have their own patch submission system via mailing list. But if you have a FC0013 dongle and want to try it, the entire change consists of only a single register value change which could easily be manually modified in the driver code before compilation.
Register change to improve UHF performance on FC0013 RTL-SDR dongles.
