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... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
Attached is a short audio clip of what I assume is a data transmission. Can anyone identify the mode? It sounds like some sort of FSK, but I am not sure. ]1144101671_1_FT0_signal.mp3[/file]
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
It is possible, but is seems a little off... FSK is what your modem uses, here is a sample of what a 1200baud one (I don't think they go slower than that...) sounds like.
It almost sounds just like a fm signal, like a signal channel being fed into vco...
... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
I dunno, if you've ever heard 300 baud HF packet, it's similar. The pitch, of course, is arbitrary for my above sample. I just adjusted the pitch so it would be nice and audible. I've no idea what the "correct" pitch is.
Here's a sample of 300 baud packet, just for reference. Similar, but not quite right. ]1144104234_1_FT6580_paket300.wav[/file]
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
It sounds like some sort of FSK with a wider than usual shift. And, it doesn't come in short bursts like packet, nor does it have a scratch scratch rhythm like fax. I'm going to guess it's one of the fancy new digital modes that didn't exist the last time I was on the radio, like G-TOR or CLOVER.
Either that or it's a gang of leprechauns farting in the bath.
... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
Possibly something similar, Steve. I should note that the reason this signal piqued my interest is that it appears at 24kHz, and at my location, its signal strength is enormous. 10dB higher than even the 60Hz background hum. Further research indicates that this is probably a signal from a US Naval facility in Cutler, Maine, destined for nuclear submarines operating in the Atlantic Ocean. This signal is transmitted into a huge antenna, with an effective radiated power of one megawatt. The fact that the signal is so huge, and the fact that the only time the signal went missing was today, precisely when Cutler's VLF transmitter was scheduled to undergo maintenance, almost conclusively proves that this is a signal from Cutler.
At any rate, while I won't be able to decrypt the transmissions, I would still at least like to identify the mode, and possibly capture some of the raw, encrypted data (and see if there's anything being transmitted in plain text).
The shift does sound awfully wide for a band in which bandwidth is so scarce. I'll see if I can filter it a bit better later tonight.
Registered Member #61
Joined: Thu Feb 09 2006, 05:50AM
Location: Mountain View, CA
Posts: 43
Chris Russell wrote ...
I dunno, if you've ever heard 300 baud HF packet, it's similar. The pitch, of course, is arbitrary for my above sample. I just adjusted the pitch so it would be nice and audible. I've no idea what the "correct" pitch is.
Here's a sample of 300 baud packet, just for reference. Similar, but not quite right.
... not Russel! Registered Member #1
Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052
After some more research, it looks like this is probably MSK, minimum shift keying. After reading up on the protocol, it should be possible to decode with in either FSK or PSK mode, but I'm not having any success. I assume this is because the data is encrypted -- it's supposed to look like jibberish even when decoded. I guess I was hoping to see something like:
KWNCU PWICN WMQNX QPC8E etc.
And what I'm getting out is junk like:
s e¥sisietesis edLie0otiesbt es eAioisd yotesieeiui yte to s e4Ntisee¦siioit eoiLtd ie£4 esLs¯iio Lºo e-ed~ibssio euPi0su cyo s
Clearly not random, clearly not anything meaningful either.
Vigilatny Registered Member #17
Joined: Thu Feb 02 2006, 02:47PM
Location: NL
Posts: 158
0024.0:NAA:US NAVY NCTS Cutler, Maine, USA:MSK ACTIVE 00024.0 kHz is currently the only frequency in use by NAA Cutler. NISBS capable ( Nato Interoperable Submarine Broadcast System )
00024.0:NPM/NBA/NSS/NLK:US Navy various sites,USA:MSK NOT ACTIVE NBA/NSS are both shut down NPM is currently only active at; 00021.4 kHz ( see this ) NLK is currently only active at; 00024.8 kHz ( see this )
The Naval Computer and Telecommunications Station in Cutler, Maine, was a communication center used to provide contact with U.S submarines in the North Atlantic Mediterranean and Arctic seas. Naval Computer and Telecommunications Station Cutler, commisioned in 1961, maintains and operates a very low-freguency (VLF) transmitter. With an output of 2 million watts, 20 times that of major radio stations, it is the most powerful in the world. The Navy shore VLF/LF transmitter facilities transmit a 50 baud submarine command and control broadcast which is the backbone of the submarine broadcast system. The VLF/LF radio broadcast provides robustness (i.e., improved performance in atmospheric noise), availability, global coverage, and has seawater penetrating properties. The submarine VLF/LF broadcasts operates in a frequency range from 14 to 60 kHz.
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Can anyone identify this data mode?
