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Old December 28th 05, 09:26 AM posted to rec.radio.shortwave
 
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Default unusual data signal at 15937.5 kHz

I found the file. I see what you means about multiple FSK, though I
think there are 8.
800
960
1120
1310 (wider that the other)
1460
1640
1790
1970



Ron Baker, Pluralitas! wrote:
wrote in message
ups.com...
Nothing heard in the SF Bay area on that frequency. 23 pst



Yeah, I'm not picking it up right now. I have been receiving
it regularly. I've specifically logged it:
2005/12/18 1156 pst
2005/12/21 2026 pst
2005/12/22 0945 pst
2005/12/23 1036 pst

I've put a .wav of it in alt.binaries.alt.




Ron Baker, Pluralitas! wrote:
I regularly pick up an unusual data signal
at 15937.5 kHz (USB). It is 7 fsk signals stacked
in frequency. They are 170 Hz shift and there
is 170 Hz between them. The Baud rate is 75.
All seven channels send the same bit stream
but offset in time by as much as 6.66 seconds.
The bits show a flat autocorrelation.
Anybody know what this is/ who is sending
it?

--
rb




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Old December 28th 05, 06:19 PM posted to rec.radio.shortwave
Ron Baker, Pluralitas!
 
Posts: n/a
Default unusual data signal at 15937.5 kHz

8 would make more sense, being a power of 2, but
it looks like 7 to me. I've posted the spectrogram
to alt.binaries.alt.

And I still am not hearing it now. My logs are
from before Christmas. Maybe it was Santa and
his elves and now that the season is past they
have no traffic.
Well, I'll keep checking for it.

--
rb

wrote in message
ups.com...
I found the file. I see what you means about multiple FSK, though I
think there are 8.
800
960
1120
1310 (wider that the other)
1460
1640
1790
1970



Ron Baker, Pluralitas! wrote:
wrote in message
ups.com...
Nothing heard in the SF Bay area on that frequency. 23 pst



Yeah, I'm not picking it up right now. I have been receiving
it regularly. I've specifically logged it:
2005/12/18 1156 pst
2005/12/21 2026 pst
2005/12/22 0945 pst
2005/12/23 1036 pst

I've put a .wav of it in alt.binaries.alt.




Ron Baker, Pluralitas! wrote:
I regularly pick up an unusual data signal
at 15937.5 kHz (USB). It is 7 fsk signals stacked
in frequency. They are 170 Hz shift and there
is 170 Hz between them. The Baud rate is 75.
All seven channels send the same bit stream
but offset in time by as much as 6.66 seconds.
The bits show a flat autocorrelation.
Anybody know what this is/ who is sending
it?

--
rb




  #3   Report Post  
Old December 29th 05, 05:25 AM posted to rec.radio.shortwave
Ron Baker, Pluralitas!
 
Posts: n/a
Default unusual data signal at 15937.5 kHz


wrote in message
oups.com...
http://www.lazygranch.com/images/temp/7fsk.gif

When I just displayed the power spectrum, it looked like 8, but in the
spectrogram, it does look like 7.


Interesting. What program did you use to produced that spectrogram?
I use Digipan for live monitoring and Matlab for analysis.
I use gram sometimes too. It has some nice features but
also some peculiarities.

Does it let you adjust the FFT size.
A shorter FFT gives better time resolution at the
expense of frequency resolution.
A longer FFT gives better frequency resolution at
the expense of time resolution.
But you probably knew that already.

--
rb


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Old December 29th 05, 08:16 AM posted to rec.radio.shortwave
 
Posts: n/a
Default unusual data signal at 15937.5 kHz

I hadn't realized it, but soundforge rev 6 has a spectrogram feature.
I'm pretty sure that rev 6 is old, but the good news is Sony bought the
company the software is considerably cheaper.

I don't believe there is anyway to change the size of the FFT.
However, I changed the scale and color scheme to do a decent job on the
data.

http://www.sonymediasoftware.com/pro...orgefamily.asp

According to the list, you need to get the full version for spectral
analysis. At this point in time, it's probably not worth it unless you
can find an old rev. There is plenty of open source audio software.


Ron Baker, Pluralitas! wrote:
wrote in message
oups.com...
http://www.lazygranch.com/images/temp/7fsk.gif

When I just displayed the power spectrum, it looked like 8, but in the
spectrogram, it does look like 7.


Interesting. What program did you use to produced that spectrogram?
I use Digipan for live monitoring and Matlab for analysis.
I use gram sometimes too. It has some nice features but
also some peculiarities.

Does it let you adjust the FFT size.
A shorter FFT gives better time resolution at the
expense of frequency resolution.
A longer FFT gives better frequency resolution at
the expense of time resolution.
But you probably knew that already.

--
rb


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