DrVarnik on YouTube has posted a tutorial video on how to receive, decode and plot AIS information. The Automatic Identification System (AIS) is a system used for automatic tracking of large ships and passenger boats. It is a similar idea to tracking aircraft with ADS-B. His method uses a RTL-SDR for receiving the AIS signals with SDRSharp, decoding received signals with AISMon and plotting the decoded information with OpenCPN. He uses VB-Cable for looping the audio from SDRSharp to AISMon, but if you have a ‘Stereo Mix’ or equivalent feature with your soundcard, that will be unneeded. Best results will be achieved using a narrow-band vertically polarized antenna tuned for 161.975 MHz and 162.025 MHz (marine VHF). A directional antenna would also likely be a benefit. You can find some designs to try lower down the page. For safety, please only use this guide on land! Wouldn’t want you getting lost at sea.
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.
“I have been getting into software defined radio via RTLSDR and found the stock antennas woeful for reception and picked up a tonne of noise from my LCD and laptop – though it’s hardly surprising. So to improve the situation and spend as little as possible I decided to make a discone antenna. After some research I happened upon VE3SQB’s site and a neat discone design program for Windows. As a compromise between frequency and unwieldyness I settled on 130MHz as the lower bound. Discones are inherently wideband and I expect the antenna to be useful for reception in the 60MHz to 1700MHz band the E4000 tuner can work with.” — http://helix.air.net.au