On 25/09/11 08:29 AM, Patrik Tast wrote: > Most interesting, > > Tell us more how you did it. > - antenna used? > - daugherboard? > - etc > > Many SDR users in Northern Scandinavia are up day and night > listening on submarine traffic on VLF. > > I use a square-loop antenna, roughly 1.5M in diameter. I have roughly 80M of 22ga wire wound onto it. This feeds a Behringer Mini-Mic 800 microphone preamplifier, which is then fed into a 96KHz sound card--no USRP required.
The software I wrote for this I call SIDsuite. It's available via GitHub: https://github.com/patchvonbraun/SIDSuite It works by measuring the received signal stength for various VLF transmitters--most of them are indeed submarine communications systems. The signal strength follows a diurnal pattern involving solar radiation and the D and E layers of the ionosphere. When there are strong solar X-ray events, that pattern is disturbed--sometimes spectacularly. -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org
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