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... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
I have a small update on the above mentioned signal. Previously, I had been capturing the 24khz signal by sampling at 48khz; this unfortunately meant that the top half of the signal was chopped off, probably explaining my inability to decode it with a fsk or psk demodulator.
Recently, I was able to purchase an external USB soundcard (an Edirol UA-1EX) that can sample at up to 96khz, allowing me to neatly sample the entire 24khz signal. This time, my msk demodulator locked on nicely and spit out the raw data. Another pass with a fsk demodulator turned up similar data, albeit at a somewhat higher error rate, since msk is not identical to fsk.
The signal is indeed from the Naval facility at Cutler, Maine. The mode is 200 baud msk data, though the character encoding is unknown, probably not knowable. The data itself is encrypted and is certainly not breakable at home.
Here is a screencap from Spectrum Lab, showing the width of the signal.
]1159377311_1_FT6580_msk_200_baud.mp3[/
file]
This is an mp3 file of the clip pictured above, and decoded below.
This is the result of two passes with an msk demodulator. Notice that slightly different results were produced each time, but that overall, the two are in good agreement.
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Can anyone identify this data mode?
