While playing around with the newly installed Gqrx SDR receiver, I have accidentally found a strong signal peaked at 399.964MHz and 399.966MHz. From the spectrum analyzer, I could not see much details about this signal so marked it as interesting beacon. The first thing to understand this of course is throw it at Google and see what came up. Surprise, less than 10k results! In fact, there were less than 170 results returned and were almost uniformly about patents on certain type of drugs. At a glance, they’ve all mentioned 1H NMR (399.964MHz) and a quick check on Wiki told me that this is the proton NMR spectrum! You can listen to the audio recording Here.

Interestingly, tuning into 399.966MHz gave a slightly different signal which has some texture in it. Here is the audio recording of this frequency.


Have absolutely no idea why they are here…

Gqrx is a SDR (software defined radio) receiver available on many platforms. It uses the GNU Radio SDR framework and the Qt graphic toolkit.


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