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#1
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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 |
#2
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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
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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 |
#4
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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 |
#5
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unusual data signal at 15937.5 kHz
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