Category: Applications

Receiving Mexican Pirate SSTV on Military Satellite Frequencies with the RTL-SDR

Happysat, a reader of 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.

More information about pirate SSTV can be found here.

Edit: From our Facebook page comments, it seems these signals are actually from Mexican pirates. More info here

Milsat Pirate SSTV
Milsat Pirate SSTV in SDR#
SSTV Image
Received SSTV Image 1
SSTV Image
Received SSTV Image 2

K2NCC’s Guide to AIS Reporting for the RTL-SDR

AIS enthusiast K2NCC has posted in our forum a link to a PDF document he has created showing how to use SDR#, AISMon and AIS Dispatcher to report AIS data to and and are websites which aggregate AIS data from various contributors around the world.

AIS is an acronym for Automatic Identification System and is a type of modern GPS based radar system similar to ADS-B used by mariners to help avoid collisions at sea.

Map from
Map from

Receiving Kicksat Telemetry with the RTL-SDR

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 his blog, Dolske has been trying to receive and record the Kicksat carrier using his RTL-SDR. He was able to capture a telemetry packet at 437.505 MHz using SDR#. He then tried to use QTMM AFSK1200 to decode the packet, but has been unsuccessful so far probably due to the weak signal he received.

Kicksat 'nano' satellite sprite.
Kicksat ‘nano’ satellite sprite.

Hak5: ADS-B on a Quadcopter carrying a Wifi Enabled Linux Computer, RTL-SDR and Coaxial Collinear Antenna

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

RTL-SDR on PureData and Max/MSP

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.

rtlsdr FM radio in Pd

rtlsdr FM radio in Max

Pranking Colleagues with the USRP B210 Software Defined Radio

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.

Earlier in the year we posted about how Oona Raisanen was able to use her RTL-SDR to receive and decode restaurant pagers (the wireless devices given out at some restaurants to notify you when your food is ready).

Balint used his USRP210 controlled by a mobile phone app to transmit a fake signal to his colleague’s pager, causing it to activate before his food was ready.

You Can Page Me Anytime – USRP B210 + GNU Radio (teaser)

Receiving Urban Drainage And Flood Control Weather Sensors

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.

Over at, blogger cparker has posted how he was able to receive and decode the RF signals sent by these stations using an RTL-SDR. Using cparker was able to determine that these stations transmit at 169.5 MHz using frequency shift keying (FSK).

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.

Urban Drainage and Flood Control
Urban Drainage and Flood Control Sensor Station

Raspberry PiRate Radio FM Transmitter

In November last year we posted a story showing how a Raspberry Pi could be used to transmit a digital AFSK signal to an RTL-SDR or other radio simply by connecting a wire to a GPIO pin.

Now an 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.

PiFm & R820T & HDSDR

New RTL-SDR Android App: SDRWeather

A new RTL-SDR Android app called SDRWeather has appeared on the Google Play Market. The new app allows you to listen to weather radio and decode EAS (Emergency Alert System) alerts. The app will only work in the US and Canada. More information about the app and its open source code can be found at

This software along with a supported USB software defined radio turns your Android device to a portable weather radio.

Current Features:
* 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

Screenshot of the Android RTL-SDR App SDRWeather
Screenshot of the Android RTL-SDR App SDRWeather

GPS Tracking with a modified TCXO RTL-SDR

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.

Modified TCXO R820T RTL-SDR used for GPS reception.
Modified TCXO R820T RTL-SDR used for GPS reception.