Project Logs

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• Sensing the RF

  piranha32 • 08/21/2014 at 02:18 • 0 comments

  In my project I have to detect presence of short pulses sent by the transmitter. The detector must be robust, must be able to automatically adjust to changing signal and noise levels, and provide a mechanism for recording geographic coordinates of the location where the signal was detected. After quick scan of available GnuRadio modules I decided to implement the detection myself, because none of the existing modules was able to do the job.

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• Architecture of the box

  piranha32 • 08/21/2014 at 01:16 • 0 comments

  My goal in building The Box was to have a universal and portable platform for experiments with software radio. The other goal was to only use components that I had at home. These two conditions shaped the overall hardware architecture of the system.

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• How to convince gpsd to talk to your GPS

  piranha32 • 08/18/2014 at 06:09 • 0 comments

  gpsd is a wonderful tool. It allows many programs to talk to one GPS device, without problems with resource allocation conflicts. The library linked to user apps takes care of parsing all the information and outputs easy to digest numbers.

  As awesome as the software is, it has several disadvantages. The most annoying of them is how the program handles detection of  speed on serial port. The authors insist on not allowing to inform the daemon about bit rate and auto-detection not always works as it is supposed to work.

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• Using VirtualBox to install OS for an embedded system

  piranha32 • 08/17/2014 at 23:19 • 0 comments

  Embedded systems are fun to play with, but installation of the OS can be a real pain. In my case the OS was not a big problem (I'm using a plain, old, boring PC hardware, after all), but as usual, the devil lurks in the details. In my case none of the monitors I have at home was able to display the video signal from the board (23" Dell LCD went just blank, while 17" LCD at least showed a message about unsupported video mode.) The only device that worked properly was a projector. Being a lazy brat as I am, I decided to not to stand at the projector holding the keyboard in one hand and the board in the other, and hack the entire process without touching the target board at all. Enter VirtualBox, a full PC system in a small window on the monitor.

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• Installation of WiFi antenna next to GPS antenna is a bad idea

  piranha32 • 08/16/2014 at 19:01 • 0 comments

  First real test came. Battery charged, receiver antenna connected to bladeRF, application started, waiting for a GPS fix.

  5 minutes passed, still waiting for GPS fix.

  10 minutes passed, still waiting for GPS fix.

  What about unlugging the WiFi dongle?

  1 minute passed - GPS' got the fix!

  WiFi antenna has to be moved from top of the box to another spot, further away form the GPS.

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