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.
The Tiangong-1 station transmits a signal at 2232.15 MHz. To get this signal into a range receivable by the RTL-SDR gat3way used a LNB (Low Noise Block) to downconvert the frequency into one that the RTL-SDR can receive. Using this setup he was able to get a decent signal copy.
Blogger Dolske has recently posted about how he was able to receive and decode signals coming from inside his body. The signals originated from a Bravo Ph Esophageal monitor which is a small wireless sensor that is attached inside your body by a doctor. It is used to monitor pH levels within the body to help diagnose esophageal problems such as acid reflux. The monitor remains in the body for a number of days continually sending data to an external monitoring device which records and logs the pH data.
Using his RTL-SDR, Dolse was able to capture the wireless monitors signal using information he found about the monitor online. He found that the monitor used amplitude-shift keying and transmitted at 433.92 MHz. After capturing some signals with the RTL-SDR, he looked at the captured waveform in Audacity and was able to decode a few packets by hand. Finally, he went even further and wrote a Firefox browser based decoder which decodes and displays the pH data on screen.
Over on YouTube user Orlando Lima shows reception of the SO-50 Saudisat 1C satellite. Saudisat is an amateur radio satellite with an FM radio repeater. Orlando listened to the downlink frequency at 436.795 MHz using an RTL-SDR, Yagi antenna and Orbitron software to track the downlink frequency in SDR#.
Over on YouTube user k2nccvids has posted two videos showing how he was able to decode High Frequency Data Link (HFDL) packets using the RTL-SDR, Ham-it-up upconverter, MultiPSK and HFDL Display. HFDL is a service similar to ACARS but sent over HF frequencies. It is used to sent short messages to and from aircraft and ground stations.
In the first video k2nccvids uses MultiPSK with the RTL-SDR directly and also uses the add on software HFDL Display to more clearly view received HFDL packets. In the second video he uses SDR-CONSOLEv2 to monitor three HFDL frequencies simultaneously, with MultiPSK and HFDL Display still being used for decoding and display.
Over on YouTube user k2nccvids has posted a short video showing the Logic Trunked Radio (LTR) Analyzer software working with SDR# and the RTL-SDR. Logic Trunked Radio is a type of radio trunking system that uses distributed control channels modulated into the analogue voice channel instead of using just one signal control channel.