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…

export CFLAGS="-Werror"
export CXXFLAGS="-Werror"
cmake ..
make VERBOSE=1

…but it does not do anything at all?

If you encounter this problem, it is likely that you overwrite CFLAGS somewehere in your CMakeLists.txt files.

For example, replace this:

set(CMAKE_C_FLAGS "-std=c99")

…with the correct one that appends the new flags instead of overwriting them:

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")

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.

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.

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).

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.