Over on YouTube user BSoD Badgers has uploaded a video showing reception of Hellschreiber on HF at 20m. To receive the HF frequencies he used a ham-it-up upconverter. He used SDR# to receive the signal and the Fldigi decoding software to decode the signal.
Hellschreiber is a fax-like communications mode used by amateur radio hobbyists.
Earlier this month we posted about a new port of the HackRF software defined radio Linux library for Android. Now the author of the Android port has created a new app called RF Analyzer. The app is basically a real time spectrum viewer that includes a waterfall display. The app can be downloaded from Github at https://github.com/demantz/RFAnalyzer.
The app currently supports the following features.
- Browse the spectrum by scrolling horizontally
- Zoom in and out, both horizontally and vertically
- Adjust the sample rate and center frequency to match the current view of the screen by double tapping
- Auto scale the vertical axis
- Jump directly to a frequency
- Adjust the gain settings of the HackRF
- Select a pre-recorded file as source instead of a real HackRF
- Change the FFT size
- Setting the frame rate either to a fixed value or to automatic control
- Activate logging and showing the log file
In the future the author intends to support the RTL-SDR and implement demodulation for basic modes such as AM, FM and SSB.
To use the app you’ll need an USB OTG (on-the-go) cable to connect your Android device to the HackRF.
Recently we posted about a tutorial showing how to receive LRPT weather satellite images from the new Russian Meteor M2 satellite. Now over on YouTube user Tom Mladenov has uploaded a tutorial video showing all the tutorial steps.
The reception process is to essentially record an IQ file of an LRPT transmission using SDR#, reduce the sample rate of the IQ file using audacity and then decode the file using LRPTrx.exe. Then finally the decoded data can be imported into LRPTofflineDecoder to produce an image.
Micheal Ossmann’s HackRF Linux library has recently been ported to Android by programmer Dennis Mantz. Dennis has also made a blog post showing how to use the library. In addition he’s uploaded a YouTube video showing off the library using an example app. The app is capable of recording an RF signal and replaying it via the HackRF’s TX capabilities. In the video Dennis shows the example app recording a broadcast FM station and then retransmitting the recording to his car radio.
A reader of our blog has recently written in to let us know about a lab sheet from the University of Colorado College of Engineering and Applied Science which clearly explains software defined radio theory with the aide of an RTL-SDR dongle.
The lab sheet starts off by showing how the RTL-SDR works at a high level, then goes on to explain the function of the R820T tuner chip and RTL2832U chip. The lab then shows a behavioural level model of the RTL-SDR which becomes useful for mathematical analysis. Finally, the lab also explains demodulation theory for FM and FSK signals and sets several lab exercises that involve writing FM and FSK demodulators in MATLAB or Python.
The zip files mentioned in the lab sheet can be downloaded from http://www.eas.uccs.edu/wickert/ece4670/lecture_notes/.
Recently we posted about a new US based source for modded TCXO RTL-SDR dongles. Now Nooelec, one of the most popular sellers of standard RTL-SDR dongles have started selling their own version of TCXO modded dongles as well. Their dongles come with a 0.5 ppm TCXO oscillator as well as an external aluminium casing for interference shielding.
A TCXO is a temperature controlled oscillator. Its advantage over a standard oscillator like the one used in a normal RTL-SDR is that its frequency will not drift as the temperature of the dongle changes.
Nooelec are also selling the aluminium casing by itself in silver and in blue for use in shielding dongles that you already have.
On this episode of Hak5, a popular YouTube technology channel, Shannon shows two Android based ADS-B RTL-SDR apps that we have mentioned on this blog previously. One is “ADS-B on USB SDR RTL” and the other is Avare ADS-B. Both are ADS-B apps that will display real time airplane positions on a map.
To run these apps you need a RTL-SDR dongle, a USB OTG cable and an Android phone.
Over on Reddit user JorgeGT has posted an animated 3D visualization of his local ADS-B air traffic data using a MATLAB script he wrote. The script collects data from a dump1090 server. If you have a copy of MATLAB, his code can be downloaded from Github here. To run the code JorgeGT writes that you’ll need to do the following.
