Article about the Frequency Xlating FIR Filter block in GNU Radio
I’ve written an article on a GNU Radio Companion block, and published here:
BPSK31 and 3D waterfall diagram in OpenWebRX
Today I’m happy to announce a new version of OpenWebRX with a BPSK31 demodulator built-in. On the video below, I’m using OpenWebRX with a HackRF to monitor the 20m band and demodulate a BPSK31 QSO:
OpenWebRX now also has a 3D waterfall diagram, featured in the video below, which in addition also shows how the secondary waterfall diagram of the BPSK31 demodulator can be zoomed by moving the filter edges around:
I’m also happy to say I’ve just graduated from university, earning a Master’s degree in electronic engineering. I’m now looking for new opportunities related to Software Defined Radio. I am also thinking about continuing my studies in this field for PhD degree.
My Master’s thesis about “Integrating digital demodulators into OpenWebRX” can be downloaded here. It covers:
- how CSDR can be used to demodulate BPSK31, BPSK63 and RTTY from the command line, and also to derive new digital modes from existing ones by changing the commands,
- how CSDR can be used as a general purpose FSK/PSK demodulator, demonstrated with decoding FSK signals sent by a YARD Stick One.
On 15 July, I’m going to have a talk about these topics at SDRA-2017, a conference organized at HAMRADIO Friedrichshafen.
I also have good news about SDR.hu: the server has been moved to a DigitalOcean VPS for better reliability.
I’d like to say thanks to everyone who uses OpenWebRX and CSDR, and also everyone who helped me with this project:
- Starting from last February, a lot of people donated to support OpenWebRX development.
- Mike Ossmann from Great Scott Gadgets donated a HackRF and a YARD Stick One that I used for development and testing while implementing digital mode support.
- My supervisor, Dr. Péter Horváth taught me a lot about digital signal processing, and he always knew where should I look after the hard to understand topics that I encountered.
Thank you everyone for your support!
If setting CFLAGS to cmake from command-line does not work
What happens if you really try to add some CFLAGS to cmake from command-line…
Talk at SDRA-2016
I was invited to talk at Software Defined Radio Academy 2016 at HAM RADIO, Friedrichshafen. I had a talk about my work on OpenWebRX and csdr carried out during the last year.
Some HTML5 3D effects
While things like this are not the most important in an SDR application, the OpenWebRX UI has been improved with some 3D animations:
hpsdrtool
I’ve created a python script that can read the I/Q samples from a HPSDR Atlas + Metis + Mercury receiver, and write them to the standard output. The code is available on GitHub:
Agreement on KiwiSDR
After writing my previous blog post, John has changed his mind, and he contacted me about resolving the situation. He made a Memorandum of Understanding about Valent F(x) giving a part of the profit of KiwiSDR to me and Andrew Holme (the author of the GPS receiver code used in KiwiSDR).
I would like to say a big thanks to a lot of people, for your amazing support! It was not possible without you!
John Seamons and ValentF(x) are selling their reputation on Kickstarter
After writing this article, John has changed his mind, and he contacted me about resolving the situation. He made a Memorandum of Understanding about Valent F(x) giving a part of the profit of KiwiSDR to me and Andrew Holme (the author of the GPS receiver code used in KiwiSDR).
During the last month, I’ve got a lot of mails from a lot of people. Thanks everyone for your amazing support! It was not possible without you!
FastDDC and GPGPU: progress toward a full HF web receiver for everyone
While developing OpenWebRX, I always wanted to make it available to hams who have various hardware, instead of supporting a specific board that you have to buy in order to use the software. The idea of a full HF receiver is very good, and I imagined if anyone could have one, not just those who buy a specific board of a specific manufacturer.
fork() and stdin behaviour
I’ve stumbled upon this: if we fork() a process, its standard input and output file descriptors remain the same for both processes. It means that the forked process can read() from stdin, and then the read data is taken away, and the original process can’t read it.
Notes on using rpitx with GNU Radio and csdr
You can find my article on Github.
Playing audio with gr-ha5kfu if Audio Sink fails
I’ve got continuous underruns and overruns, clicks with Audio Sink in GNU Radio, so I used the Execute External Process Sink in gr-ha5kfu, with csdr, and the mplayer command line tools.
Windows binaries for eagle2fritzing
One of my friends needed this for doing his work, so I compiled it for him:
Installing WSPR on Linux Mint 17
GNU Radio on the Raspberry Pi 2
rtl_sdr in VirtualBox
The screenshot was made of a VirtualBox VM running Ubuntu 14.04 on a Linux MINT 17 host.
rtl_sdr tool works inside the guest OS, after sharing the USB dongle with the guest under the Devices, USB Devices menu.
Quick setup instructions for OpenWebRX on Ubuntu
This is an absolute quick guide to install OpenWebRX, an SDR receiver software with a web UI. If you need more information or have a problem, please look at the GitHub page of the project.
Headless first boot with Odroid-C1
It was quite easy, but I’d like to highlight some information:
Debian package for 32-bit GitHub Atom text editor
I’ve recently had difficulty installing GitHub Atom on my PC as only an amd64 package was available on the official site. Here I’ll provide an i386 build:
Calculating CPU usage with python on Linux
This small script prints overall CPU usage in a Linux system. You can use the get_cpu() function to get the CPU usage between 0.0 and 1.0 (all CPU cores were taken into consideration, so the maximal value is also 1.0 on a multi-core system).
Returning structs in emscripten
Based on the discussion over here, I’ve created a simple code sample.
LUT based frequency translation in libcsdr
I’ve just written a shift_table_cc function for libcsdr.
OpenCL on Linux Mint 17 and NVIDIA Quadro 1000M
You will need to do something like this (note that I have xorg-edgers and you may have to replace 346 with the actual version number):
Some notes on ShinySDR
ShinySDR is a bit similar to my OpenWebRX project.
I could not find any good screenshots on the Internet about ShinySDR, so here is one:
OpenWebRX performance tests
OpenWebRX serving 10 clients simultaneously (and also running the browser windows on the same machine), without audio underruns.
Rational Resampler problems
If you have zero signal coming out of the Rational Resampler block in GNU Radio, or such strange signal as on the top right:
"Bundle" utility class in python
I liked this python recipe and I’ve extended it a bit, to make this class also iterable.
Read-only root filesystem on Raspbian
While running Raspbian on my Raspberry Pi (Model B), the SD card repeatedly got corrupted when I removed the +5V power without properly halting the system.
How to use GNU Radio gr-osmosdr block on a VM
First question: why would anyone want to set up GNU Radio on a virtual machine?
Because you can connect to an rtl_tcp server to get I/Q samples from there, and do actual processing on the VM.
Use of Message Sink in GNU Radio Companion
I’ve implemented a power spectrum display to demonstrate a way to postprocess the data gathered from GNU Radio in python.
Possible use of RTL-SDR for amateur radiolocation
Having watched Balint Seeber’s SDRDF presentation, I and HA1OP had some interesting ideas.
LabVIEW and RTL-SDR interface
I’ve made an interface between the popular RTL-SDR compatible hardware and NI LabVIEW. It’s not complete, but just got it working. It’s a set of SubVIs that can be used to connect to an rtl_tcp server. I’ve also implemented a WFM demodulator, so I could listen to some FM broadcast in LabVIEW.
Checking out Raspberry Pi network speed
I’ve just installed a tool called iperf, that can actually determine the real available network bandwith between two nodes in your network. The result listed below might not be the most accurate, as I was connected to the Pi with a Linksys 8 port switch in between.
Weak Signal Propagation Reporter tests
I’ve recently made some experiments with the great WSPR software, which can dig out and process so weak signals that you can’t even hear. Along with the software, there’s a great web interface on which you can see the contacts on a map.