Over on his YouTube channel user Gareth has uploaded a video that shows a full tutorial on quickly decoding an On Off Keyed (OOK) signal with a HackRF (or RTL-SDR) and the Inspectrum software. Once decoded he then shows how to use a Yardstick One to duplicate the signal.
Inspectrum is a Linux based program that allows you to easily determine various parameters of a digital modulated signal by positioning an overlay over the waveform of a signal recorded with an SDR. Basically Gareth’s process is to first extract signal level values using Inspectrum, then secondly use a simple Python program to turn these values into binary bits, which gives him the data packet. He is then finally able to write another quick Python program to interface with the Yardstick One and retransmit the string.
The Yardstick One is a multipurpose radio (not a SDR) for transmitting modulated signals like OOK.
My quickest and easiest method for OOK signal decoding & replication in 2016
Over on his blog Michael Carden has produced a tutorial showing us how to use SDR-J on the Raspberry Pi 3 for receiving Digital Audio Broadcast (DAB) radio. DAB is a type of digital broadcast radio used in several countries outside of the USA for general broadcast radio programs. It usually provides clearer digital audio compared to FM broadcast.
His post starts from scratch, showing how to create a Raspberry Pi image file and configure the Pi, then shows how to install and use SDR-J.
SDR-J is also available for Windows and is compatible with the RTL-SDR and other radios such as the Airspy and SDRplay.
Akos from the RTLSDR4Everyone blog has recently posted three new articles. The first article reviews the Janilab LNA Preamp which has a frequency range of 1 MHz to 3 GHz and an adjustable gain. In the review he compares reception with and without the preamp at shortwave frequencies and at ADS-B frequencies. Finally he also compares it against the LNA4ALL and LNA4HF, and notes that they generally have better specs than the Janilab preamp, but the disadvantage is needing two to cover HF + VHF/UHF, meaning an increase in costs.
In his third post Akos does a review on small ADS-B antennas. These are small whip type antennas that are tuned for 1090 MHz. In his testing he found that a telescopic antenna gave significantly better results that the ADS-B whip, but recognizes that these are designed for pilots and light aircraft owners who need a small sturdy antenna.
One handy thing about using our bias tee enabled RTL-SDR dongles is that you can easily power a remote LNA, such as Adam’s LNA4ALL. The bias tee sends DC power down the coax cable eliminating the need for a remote power supply. However, in our current iteration of the dongle the bias tee must be soldered on via a jumper, and once soldered it is permanently providing DC power down the coax cable. This is fine if you are always using a LNA, but if you want to one day remove the LNA and use a shorted antenna, you cannot. A shorted antenna is an antenna designed with the center and shield of the coax connected together creating a DC short (e.g. J-pole and QFH antennas). If you connected a dongle with the bias tee on to a DC shorted antenna you would short circuit the 5V bias tee.
Over on his blog Adam shows that a solution is to create a simple DC block component. A DC block component is nothing more than a series capacitor. However Adam points out some important tips including the need to use a small 0603 sized SMD capacitor with 100pF of capacitance in order to ensure operation over the entire frequency range that the RTL-SDR covers.
A commercial DC block component (TOP) vs. Adams home made DC block component (BOTTOM)
AmaateurRadio.com and NooElec are currently running a big competition to give away 50 of their new SMA RTL-SDR dongles (branded as NooElec SMArt). To enter simply go to the competition post on amateurradio.com and comment on theirpost (not ours!). The compeition closes on August 7 at 20:00 UTC.
They are giving away a total of 50 units: two bundles that come with their SMA RTL-SDR and Ham-It-Up Upconverter, one bundle with a Raspberry Pi and RTL-SDR dongle, three double pack RTL-SDR + antenna bundles, ten double packs of RTL-SDR dongles, ten RTL-SDR + antenna sets, and ten sets of just the RTL-SDR dongle itself.
The NooElec SMART is NooElec’s latest RTL-SDR variant which like ours comes with an SMA coax plug and metal enclosure.
Over on YouTube user Crazy Danish Hacker has been working on uploading an entire series on GSM Sniffing with an RTL-SDR. His series is explained in a slow and clear presenting style, and it starts at the very beginning from installing the RTL-SDR. The tutorial series is not yet complete, however he is uploading a new video almost daily. Presumably the series will end with showing you how to receive text messages and voice calls originating from your own cellphone.
So far he has shown how to install the RTL-SDR, identify GSM downlinks, install and use GQRX and kalibrate, locate nearby cell towers, install and use GR-GSM and how to extract the TMSI & KC keys from your cell phone. To obtain the TMSI & KC keys he shows us how to use an Android tool called usbswitcher which forces the phone to use its USB modem interface, from which the keys can be obtained.
The video below shows his teaser video on the series. Check out his GSM playlist to view the full series.
GSM Sniffing Teaser - Software Defined Radio Series!
Valo is a software service for real time big data streaming analytics of data from many sensors. On their website they explain their service as follows.
Valo is a single platform for streaming (real time) and batch (historical) data analysis. Valo provides multi-paradigm big data storage for both semi-structured and numerical data. Valo contains a powerful analytics engine for processing all of this data. Finally Valo is super simple – a single tool that can be up and running in minutes.
Rémi writes that what he’s done is simply a proof of concept that shows the power of Valo. He writes that one such interesting future development could be using Valo to detect FBI/CIA surveillance aircraft. Previously we posted about how an RTL-SDR user discovered these surveillance aircraft by their odd circular flight paths. The analytics engine of Valo could be used to automatically detect odd flight patterns such as from these surveillance aircraft.
Plotting the history of aircraft coming into land at HK airport
Network transparency. Process the data remotely and send to the client only waterfall pixels and filtered narrowband channels instead of the entire SDR baseband. With this, you can use the SDR remotely over WAN.
Multiple demodulators running at once. How the hell can this be missing?
History browsing. It happens to me all the time: I see a new station scrolling on the waterfall. Before I manage to tune to it, it disappears (or at least the callsign is over). I have 8 GB of RAM, so why can’t I store the last minute of the entire SDR baseband for future reference?
Pluggable demodulators. Why is it so much pain to add GSM, Tetra, Tetrapol and other modes to existing software? I just want to provide a binary and have the data piped to stdin.
Squelch sucks. The squelch should not care about absolute signal level, but about level relative to surrounding channels. Additionally, it should have hysteresis and a small buffer, so when it triggers, it correctly replays the beginning of the conversation. Oh, and when recording, the squelch should timestamp the parts of conversation.
Histogram. It is difficult to see clipping on the FFT output. Why don’t we have histogram of samples?
Autotune/AFC. Obvious.
Scanner. Both for automatic demodulating all peaks in the spectrum and for retuning the SDR and finding stations. Even the crappiest rtl-sdr has 2 MHz bandwidth and can retune in 50 ms. This means 1600 channels per second. Compare this with commercial scanners.
At the moment one interesting plugin for Kukuruku is the TETRA plugin. The plugin appears to use tetra-listener and TERAPOL-kit as the demodulators, and simply passes the signal data to them for decoding and audio output.
The installation instructions can be found on the user guide. So far we unfortunately haven’t been able to install and test the software due to several compilation errors occurring, so if anyone tries this out and gets it to work, please post any installation tips in the comments.
Kukuruku running and demodulating TETRA audio with a plugin.
