Over on YouTube channel TheSmokinApe has uploaded a video about using RF filters with an RTL-SDR. In the video he first explains why FM bandstop and AM high pass filters might be required when using a software defined radio in order to avoid overloading the SDR with very strong signals. He goes on to test and review our RTL-SDR Blog FM Bandstop and AM Highpass filters, by testing them on a spectrum analyzer.
Thank you to Marco for submitting news about the release of his Linux based RTL-SDR FM and DAB tuner software package named Guglielmo. The code is based on the Qt-dab and sdr-j-fm packages, with some bug fixes, a new GUI and new audio features implemented. Marco writes:
Guglielmo implements a simple FM and DAB receiver based on Qt and the Qt-dab and sdr-j-fm packages.
The primary reason it is being developed is there is a lack of media centre quality Open Source Software Defined Radios: most of the packages out there focus more on hobbyist features, such as signal and content monitoring, leaving out media features like a volume slider or MPRIS control.
Yes, I have blown the ribbon tweeter fuses on my maggies because my previous go to SDR DAB receiver started at full blast, and I run my media centre headless: I don't really want to scramble for a VNC session when I want to stop the music, when I could simply use KDE connect on my phone.
There is also a distinct lack of FM SDR receivers, which is disappointing, since, at least in the UK, for reasons of cost, most stations transmit at a fairly poor bitRate, if not downright in mono, and FM stations seem to still be a better proposition in terms of sound quality.
If you're interested in trying it compilation instructions are available on the GitHub, and there is also a ready to use AppImage on the GitHub releases page too.
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 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.
The popular YouTube technology show Hak5 has recently been posting videos related to software defined radio and more specifically RTL-SDR. Two of their recent videos are about an easy to follow GNU Radio tutorial for complete beginners. In the first tutorial they show how to add an RTL2832U source in GNU Radio and output it to a FFT Sink. In the second tutorial they go further and show how to build an FM Receiver.