Capture 0.0.5

05.10.2012 18:21

There's a new version of the capture code available from the am433 distribution. This version allows you to disable modulation auto-detection using the -M command-line argument and has a more robust detection of plain binary encoded packets.

In case you don't know what I'm talking about: capture tool is a part of my am433 project. It takes a low-frequency digital signal (say, with a 48000 Hz sampling rate or there-about), chops it into individual packets and applies some heuristics to determine the packet modulation type. You can think of it as a box that takes a continuous stream on one end and returns decoded packets and some meta-data on the other end. Optionally you can plug it into libpcap and your favorite packet dissector.

Screenshot of capture and Audacity

It was originally meant to decode the digitalized baseband data from my simple 433 MHz AM receiver. However it turned out quite useful for other applications as well. For example, it can be used with GNU Radio to decode transmissions on various frequency bands and modulations, as long as we are talking about devices that communicate infrequently with small packets (EnergyCount 3000 is one such case). With a proper receiver hardware it can even be used to decode infrared transmissions.

It can currently get data from an ALSA device or a file. You can also point it to a named pipe, which is currently the easiest way of using it from GNU Radio. It would be great though if someone would wrap it in a proper GNU Radio block.

Posted by Tomaž | Categories: Code

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