signal around 25khz
 

http://www.lazygranch.com/sound/25khz_snip.wav
I recorded this a bit north of San Francisco. I didn't log the mode,
but I'm sure I was in sideband (unknown which).

ID????

wrote:

http://www.lazygranch.com/sound/25khz_snip.wav
I recorded this a bit north of San Francisco. I didn't log the mode,
but I'm sure I was in sideband (unknown which).

ID????


25 khz or 25 Mhz? I doubt there's anything except a few data signals
around 25 khz, I know WWVB operates at 60 khz. 25 Mhz, on the other
hand, is on the upper end of the HF spectrum, around the CB band. I
believe some CB freebanders may hang out in that area.


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25Khz, not 25Mhz.

You have time interval signals and other strange things down in the VLF
range. I am not sure what this one is. Sometimes, there are narrow shift
data transmissions down there.

Pete

wrote in message
oups.com...
25Khz, not 25Mhz.

wrote in news:1110418417.048294.322430
@g14g2000cwa.googlegroups.com:

http://www.lazygranch.com/sound/25khz_snip.wav
I recorded this a bit north of San Francisco. I didn't log the mode,
but I'm sure I was in sideband (unknown which).

ID????


Submarine attack orders?

wrote:

25Khz, not 25Mhz.

Thats' very low for good reception on a typical shortwave antenna. What
kind of antenna were you using? What receiver? I would suspect some kind
of local signal (noise?) getting into the radio on such a low frequency
before assuming it is coming from long distance propagation but maybe
you are close to the transmitter.

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It's on a Wellbrook ala 100. The signal is real. If you listen to the
signal, it sounds like FSK, but a software decoder (skysweep) I tried
won't lock on it. The radio is a AR7030, so the low frequency reception
is pretty good. I have no trouble getting the 100khz loran, and 60khz
time signal.I've even demoded DGPS.

That was my guess, the the vlf.it website says all that stuff is around
8khz. I was probably within 20 miles of a coast guard antenna farm when
I recorded the signal.

So for who are these signals intended?

The signal was quite strong, so you are probably correct. When you
don't know exactly how to monitor a signal, it is tough to nail the
frequency exactly. Do you know the mark/space frequencies?

In article .com,
wrote:
So for who are these signals intended?

Most of my books are 15-20 years old, so they may be a bit out of date.

In _Nuclear Battlefields_ by Arkin and Fieldhouse, a book on the
infrastructures for nuclear war from 1985, they say that they're used
for communications with submarines. That book says there are four
transmitter sites in the Pacific, (Northwest Cape, Australia,
Yosami, Japan, Jim Creek, Washington, and Wahiawa, Hawaii).

The signal was quite strong, so you are probably correct. When you
don't know exactly how to monitor a signal, it is tough to nail the
frequency exactly.

I cheated. That is out of a Grove book, their _Shortwave Directory_
dated 1988, out of a longwave logging list credited to the LWCA
(Long Wave Club of America?). They also list stations in Maine and
Puerto Rico. But if you know your BFO offset, you can get a good idea
if you zero beat, or otherwise measure the frequency, like with a 0'scope.

Do you know the mark/space frequencies?

It's MSK, Minimal Shift Keying(?). It's a very narrow shift, related
to the baud rate. Even then, they have to switch the antenna tuner in
sync with the modulation, according to some ham friends who got a tour
of the place many years ago. (They date from the 1950's or eary 1960's).


Mark Zenier Washington State resident