YouTube user mutezone has uploaded a video showing a comparison between several portable shortwave radios and the RTL-SDR. His results show that the portable radios performed better than the RTL-SDR dongle at shortwave-dxing, however we are unsure of what method he used (direct sampling or upconverter) to get access to the shortwave bands on the RTL-SDR.
Update: KN0CKs products are now available at http://www.kn0ck.com/HF_SDR/.
Previously on this blog we’ve seen KN0CK release his custom modified RTL-SDR tuners which have built in upconverters for accessing the HF bands. Revision 5 of the KN0CK receiver is now almost ready for sale, and will be sold over at KF7LZE’s webstore Easy-Kits.com.
Revision 5 promises to be lower priced as it will run using the direct sampling mod instead of using an upconverter which would require more components. It will also use a Mini-Circuits MAR 8 wideband amplifier to improve weak signal performance.
Amateur radio hobbyist LA3ZA shows an image on his blog showing how busy the 70cm ISM band can be in his area in Norway. He uses a roof mounted 1.7 m long vertical antenna with 7.2dBi gain in the 70 cm band. Each signal burst may come from a remote car key, weather monitor, electricity monitor, or other telemetry device. Some of these signals may be decodeable with rtl_433.
YouTube user Drvarnick has uploaded a video showing how he receives Orbcomm satellite data with the RTL-SDR. To do this he uses a a homemade 1/4 wave antenna, SDR# and the Orbcomm-Plotter software by COAA.
COAA describes Orbcomm satellites as
a satellite communication system (www.orbcomm.com) providing two-way data and positioning service to small, portable user terminals in the VHF frequency bands. You can use a simple VHF radio receiver (scanner) tuned to the band between 137 and 138 MHz to pick up the strong signals from these satellites. With OrbcommPlotter you can decode the telemetry and find out the positions of the satellites, their operational status and their uplink and downlink channels. Unlike most satellite signals, there are so many Orbcomm satellites that there is likely to be one within range of almost any spot on Earth at any time of the day or night.
YouTube user mutezone has uploaded a video showing some data communication packets from the International Space Station (ISS) being received with the RTL-SDR. To receive the packets he used SDRSharp, and piped the audio using a virtual audio cable to the Qtmm AFSK1200 Decoder.
I tried to get the ISS (International Space Station) data comms on 145.825 MHz while the satellite was in orbit close to my location & it worked, even though it can go off frequency due to atmospherics & such. On this day, I caught it when it orbited twice around my location in the space of almost three hours. The data comms was decoded on the 2nd attempt. The antenna I used was an omni placed outdoors, & also using a TV + radio signal booster.
For anyone interested in getting the ISS, you have to wait until it orbits close to your location, & I fully recommend a decent aerial that should be placed externally. You can check the ISS tracker websites to see live updates of when & where it will orbit. Here is a link to one website…List of frequencies link…
Back in November we posted about Oona’s work with decoding radio controlled bus stop display signs using her RTL-SDR. Oona has given a talk at the Chaos Communication Congress about her work on decoding FM-RDS and the bus stop displays. The talk is now available on YouTube.
How I discovered mysterious hidden signals on a public radio channel and eventually found out their meaning through hardware hacking, reverse engineering and little cryptanalysis.
A story about my experiences with FM-RDS (Radio Data System), a digital subcarrier embedded in FM broadcast transmissions, and also cryptanalysis of the weakly encrypted TMC traffic messages contained therein. I originally found about the existence of such transmissions in a roundabout way, by using a spectrum analyzer program to examine intermodulation distortion in my radioâs Line Out audio. As it turned out, the inaudibly quiet distortion, probably caused by the radioâs stereo demuxer circuitry, contained all the information needed to decode all RDS data present in the transmission. I will demonstrate the journey I took and give a short introduction to how the data is actually encoded. Live acquisition of local RDS data depending on signal conditions in the premises.
As a bonus, I’m introducing yet another little-known FM subcarrier called DARC, and my recent reverse engineering of the bus stop display radio protocol used in Helsinki.
Andrew Reiter a researcher at Veracode has given a talk at the Chaos Communication Congress about building a distributed RF scanner array using cheap RTL-SDR dongles. This talk has been uploaded to YouTube.
Software-Defined Radio (SDR) has increased in popularity in recent years due to the decrease in hardware costs and increase in processing power. One example of such a class of devices is the RTL-SDR USB dongles based on the Realtek RTL2832U demodulator. This talk will discuss my experience in building a distributed RF scanner array for monitoring and spectrum mapping using such cheap SDR devices. The goal is to help the audience understand the what, why, and how of building their own RF monitoring array so that they will be able to do it themselves. In this era of increasingly being “watched”, we must be prepared to do our own “watching”.
Software-Defined Radio (SDR) has increased in popularity in recent years due to the decrease in hardware costs and increase in processing power.One example of such a class of devices is the RTL-SDR USB dongles based on the Realtek RTL2832U demodulator. This work investigates building and running an RF scanner array for monitoring and spectrum mapping using cheap SDR devices. The array allows for both RF sampling and power analysis to be split over multiple systems in order to increase capture and spectrum analysis capabilities. The system allows for “strong signal capture” as well as, simply, signal modeling with “strong signal alerting”. Also discussed will be using the array versus USRPs and the issue of antennae for all of the devices. I will explain the mistakes I made in building the array and what I did to attempt toovercome such pitfalls. The code for running the array will be introduced and released for public consumption. In addition, while we target the RTL-SDR devices, we will discuss the feasibility of including non-traditional SDR hardware in the array, including non-Realtek tuner cards and inclusion of HackRF devices.
Back in July we posted about Travis Goodspeed’s project on setting up a satellite dish that automatically tracks satellites in low earth orbit, where he uses an RTL-SDR for the radio. Travis gave a talk on this project at the Chaos Communication Congress conference, and the video has now been uploaded to YouTube.
Satellites in Low Earth Orbit have tons of nifty signals, but they move quickly though the sky and are difficult to track with fine accuracy. This lecture describes a remotely operable satellite tracking system that the author built from a Navy-surplus Inmarsat dish in Southern Appalachia.
The entire system is controlled through a Postgres database, fed by various daemons spread across multiple machines. So when I click on a satellite on my laptop or cellphone, it runs “UPDATE target SET name=’Voyager 1′;” and the motor daemon then begins to track the new target while the prediction daemon maintains accurate estimates of its position in the sky. Additional daemons take spectral prints or software-defined radio recordings of the targeted object for later review.
