Over on YouTube, Stephen Ong has posted a video of his standalone Terratec RTL-SDR and BeagleBone Black based spectrum analyzer. What makes this unique is the lack of computer needed and dedicated 7 inch touch LCD screen (CircuitCo LCD7 cape). Powered by 6 AA batteries, the unit is nice and portable. BeagleBoards are low-cost, fan-less single-board computers based on low-power Texas Instruments processors featuring the ARM Cortex-A8 core. The BeagleBone Black DevKit used in the video costs around USD$50. He demonstrates the unit showing the RF spectrum of commercial FM stations, car remote transmitters, analog TV (PAL B) broadcast, DVB-T broadcast, cellular GSM900 and a DECT cordless phone.
For more than 50 years the National Oceanic and Atmospheric Administration’s weather satellites have been helping monitor the earth’s weather patterns. Now over on YouTube max30max31 (IZ5RZR) has posted a tutorial on how you can receive images from the NOAA weather satellites (NOAA-9, NOAA-15, NOAA-18, NOAA-19) at home using an RTL-SDR. He gives a full walk through of using Orbitron to track the satellites, WXtoImg to decode received images and using SDRSharp to tune your RTL-SDR. He also suggests building and using a QFH Antenna or Turnstile Antenna with your RTL-SDR to receive the satellites.
Here is a list of programs used and homepage links:
Travis Goodspeed has shared a project on his blog about his adventure in tracking low orbit satellites using a fairly complex setup. He is using a dish intended for connecting to one of the Inmarsat satellites while at sea on a maritime vessel, a EiBotBoard connected to a BeagleBone for motor control and a RTL-SDR for receiving radio signals from the dish. His goal has been to track the whole sky, including moving targets and it looks like he has been pretty successful.
“At Black Hat DC in 2008, I watched Adam Laurie present a tool for mapping Ku-band satellite downlinks, which he has since rewritten as Satmap. His technique involves using an DVB-S card in a Linux computer as a receiver through a 90cm Ku-band dish with fixed elevation and a DiSEqC motor for azimuth motion. It was among the most inspirational talks I’d ever seen, and I had a blast recreating his setup and scanning the friendly skies. However, such a rig is limited to geostationary satellites in a small region of the sky; I wanted to see the whole sky, especially the moving targets.
In this article, I’ll demonstrate a method for modifying a naval telecommunications dish to track moving targets in the sky, such as those in Low Earth Orbit. My dish happily sits in Tennessee, while I direct it using my laptop or cellphone here in Europe. It can also run unattended, tracking moving targets and looking for downlink channels.” — Travis Goodspeed
Over on the RTL-SDR Facebook Page, Boris Lukac has shared a link to an Instructable by tigers58 for a omnidirectional fractal HDTV antenna. The simple build covers 50-1100MHz making it perfect for general use with a RTL-SDR and for grabbing some extra HDTV channels when not hooked up to your dongle. The supplies needed to build the antenna may already be laying around your home or workbench:
A piece of poster board or suitble material
Printer with paper to print out the pattern PDF
Thumb-tack (or other sharp pointy tool)
10.5 ft of 22-24 AWG copper/aluminum wire
Crimp connector and tool to crimp with
A length of 300 Ohm Twin Lead, or, an in-line 300 Ohm to 75 Ohm matching transformer (tigers58 also states he has had success with just directly connecting RG-6 coax to the antenna leads)
Other tools such as a screwdriver for attaching the antenna leads to the matching transformer and craft knife or other small sharp blade for cutting slots into poster board.
“After reading an article about the use of fractal mathematics in the design of cell phone antennas that have incredible bandwidth in spite of their extremely small size, I began to experiment with using a very simple fractal pattern, the Koch Snowflake, as the basis for an easy to build indoor HDTV antenna. The result of that experimentation is presented here as what I believe to be not only the best DIY HDTV antenna, but the also the simplest to build, not only in terms of the materials needed, but also in the labor required. As the holder of an Extra Class amateur radio license, I know there is no such thing as a “magic” antenna, but I started referring to this antenna as the magic antenna when I discovered that it had such amazing bandwidth, covering digital channels 2 through 60. So, with that in mind, let’s get started.” — tigers58
With many people already having these items on hand, this could be a quick cheap project to help increase the signals you are able to pick up with your RTL-SDR Dongle. Be sure to check out the Instructable page for all the steps needed to build this antenna. Keep in mind, with a wideband antenna like this, it may introduce more noise. Depending where you live and what is around your antenna, your results may very. Keeping the antenna flat may also allow for more directionality while reducing noise from sources out of the direction you wish to receive.
lui_gough from Gough’s Tech Zone has a new post featuring his interest and progress in improving the reach of his ADS-B reception and plotting ability. His recent project involves using his ADSBpi (Raspberry Pi, RTL-SDR & dump1090), his home PC and another remote PC controlled over the internet. A diagram of this setup can be seen below.
In order to get the most coverage as I can sensibly get, I leveraged my ADSBpi, my main desktop and another machine I have access to which is geographically much closer to the airport via VPN. — lui_gough
This allows him to receive signals from a much larger area than would be possible with a single antenna, single location setup. He does mention a few caveats however, like the increased chance of occasional false decode which can mess with the plotting by visualizing a plane that is unrealistically far away. A big boost to the usability of his project was using Cygwin to compile dump1090 under windows. This allows him to use the dump1090 ADS-B hub features (decoding appears broken under Cygwin compilation) without having to dedicate a machine to linux or use a virtual machine.
Click here to read the full story on his blog. Be sure to check out all of Gough’s Tech Zone as he has few other interesting posts involving the use of RTL-SDRs to receive ADS-B
“Monitoring 433.9 MHz – picking up plenty of local weather temperature sensors and the likes. Using a newsky dvb-t tuner and a modified version of gqrx that supports rtl sdr. Antenne is a 2m/70cm in my attic.” — trylleklovn