Happysat, a reader of RTL-SDR.com wrote in to let us know his experience with receiving Milsat pirate SSTV images using his R820T RTL-SDR and his homebrew QFH antenna. During his research he found that Brazillian Mexican Pirates hijack military satellite transponders to send SSTV pictures of their families on 255.560 MHz 22.4° West UFO F7 (USA 127).
Happysat writes that he found an active signal on that frequency most of the time. To receive the SSTV signal happysat used the free RX-SSTV software.
SSTV is an acronym for slow scan television and is a mode usually used on HF (0-30 MHz) frequencies by ham radio enthusiasts for sending out digital calling cards.
Recently a bunch of amateur radio nano-satellites known as ‘Kicksats‘ were launched on the latest SpaceX rocket. So far the Kicksat carrier has been successfully deployed, which is essentially the box containing the nano-satellites. On May 4, the nano-satellites known as ‘sprites’ are due to be deployed from the carrier.
Both the carrier and Kicksat sprites have telemetry signals which are receivable with the RTL-SDR. As the sprites transmit using only 10mW of power, a high gain Yagi antenna and an LNA are required to receive their signals.
Over on YouTube, Hak5 a electronics enthusiast channel has posted a video showing an interesting ADS-B project they undertook.
The Hak5 team took a quadcopter up on top of a high mountain, attached to it a WiFi Pineapple (a small WiFi equipped Linux computer), an RTL-SDR dongle and a coax collinear antenna and then flew it up high. They ran dump1090, a Linux based ADS-B decoder on the WiFi pineapple and then broadcast the decoded information back to a laptop on the ground.
Although the results were less than favourable, it is still an interesting project to explore. Their poor results may be due to a nearby RF broadcast tower which could have been overloading the dongle, or EMF from the quadcopter motors.
Tracking Aircraft over 300 miles away! Mountain + Drone + SDR, Hak5 1609
At the beginning of March we posted about Tom Zicarelli who had created a Max/MSP wrapper for the RTL-SDR. Back then he said he was also working on a wrapper for PureData (PD). Now Tom has written the wrapper and uploaded a video showing a demonstration of the RTL-SDR working in PD. He has also uploaded a new Max/MSP wrapper video. Tom plans to make the wrapper available in the next few months.
Max/MSP and Pure Data are graphical programming tools for creating music, sound, video and interactive graphics applications.
The Ettus USRP B210 is an advanced $1,100 software defined radio that is capable of both transmit and receive. Balint, one of the researchers at Ettus, has posted a video showing how he was able to play a light hearted prank on some of his colleagues using the B210.
In Boulder, Colorado (and possibly other US cities) there is a radio based weather monitoring system known as ‘Urban Drainage and Flood Control’. This is a system that monitors rainfall and other weather information and transmits data using the ALERT protocol.
Using his RTL-SDR and GQRX, he made a recording of some of the weather station packets on that frequency. Next he used a command line utility called minimodem to convert the recorded packets into binary data. After looking up the protocol online, he was then able to understand the binary string and extract the station ID information from it. Cparker then went on to write code that would plot the received stations on a map by cross referencing the station ID with a website containing location information about these sensors. Finally, he managed to get the whole system running live on a Raspberry Pi.
Now an rtl-sdr.com reader has written in to let us know that this concept has also been used before to create a 1 – 250 MHz FM transmitter using the Raspberry Pi and a program called PiFM. It uses the same concept of connecting a wire antenna to one of the GPIO pins but modulates the frequency using hardware on the Rpi meant to generate spread spectrum clock signals. It is claimed that it can transmit up to 50m away.
Below we show an example YouTube video of the Raspberry Pi FM radio transmitting to an RTL-SDR running HDSDR.
This software along with a supported USB software defined radio turns your Android device to a portable weather radio.
* Listen to weather radio in the US/Canada.
* Decode EAS Alerts US/Canada
* Selectable Pre-defined Frequencies
* Alert Notifications
* Widget to display alerts
* Option to unmute audio when alert recieved
* FIPS and CLC Location Code Databases
* Event Code Database
* No internet connection required
Possible future features
* Switch to using rtl_tcp_andro
* Option to only show alerts if you are currently in the affected region
* Affected region map
Michele from Michele’s GNSS blog has posted his results with using a modified R820T RTL-SDR with Temperature Controlled Oscillator (TCXO) for GPS reception and decoding. The RTL-SDR is capable of tracking GPS even without TCXO but improved performance can be expected with a more stable oscillator. He notes that the R820T with it’s 3.57 MHz IF is ideally suited for GPS reception when combined with an active GPS antenna. Using this setup he was able to track GPS satellites and the Galileo E1B/C GNSS satellites as well.
Michele modified his R820T RTL-SDR with a 28.8 MHz TCXO he obtained from a friend. It is however possible to purchase modified TCXO R820T dongles directly from the 1090mhz webstore.