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Author Topic: Need help on multi-tone signal ID  (Read 258 times)

Offline caylorman

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Need help on multi-tone signal ID
« on: July 31, 2020, 0311 UTC »
Need some help identifying a digital transmission I'f found on 6.775 MHz, 7.68MHz, 10.267 MHz, all in USB.  Sometimes it's the short MFSK burst, sometimes its longer runs split up with  4, 6, and 8 carrier PSK streams.  It's pretty loud at my location (NE Indiana).

https://drive.google.com/file/d/1muzOtXHHL8aGDUZ130l6JgVCZPBg7LWX/view?usp=sharing


Thanks,
Caylorman
Generally recording from Northeast Indiana
Kenwood TS-570D, SDRPlay RSP2, 107' longwire @ 30'
QSL's appreciated, caylorman<at>gmail.com

Offline Strange Beacons

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Re: Need help on multi-tone signal ID
« Reply #1 on: July 31, 2020, 1940 UTC »
I tried decoding your sound file using several different modes in FLDIGI. The only mode that even attempted to decode it was MFSK128L. And as you suggested in your post, yes, I'm pretty sure that it is a type of MFSK.

So from what you have posted, you have heard this signal at the three frequencies you provided. Was this an intermittent signal, or did it run for many minutes at a time? Or hours at a time?

I just checked all three frequencies that you provided, using a KiwiSDR located in Edinburgh, Indiana. Nothing heard.

But this is definitely an interesting signal.

Curt | W9SPY | Strange Beacons

Offline caylorman

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Re: Need help on multi-tone signal ID
« Reply #2 on: August 04, 2020, 0349 UTC »
As an example, here's how often it was observed between 0354 and 1518 UTC on July 31, 2020:

7.680 MHZ, 0435 UTC: 10 repeats of the MFSK pattern over approximately 30 seconds, 30 second pause, 15 repeats of same pattern over 40 seconds, 22 second pause, 15 repeats of new longer pattern over 40 seconds.

7.861 MHz, 1158UTC: 21 repeats of MFSK pattern over approximately 1 minute.

7.860 MHz, 1205UTC: 15 repeats of MFSK pattern over approximately 45 seconds.

7.680 MHz, 1258UTC; Approximately 7 minutes of what sounds like two stations, one strong and one faint, in two way comms link using MFSK.  Here's a link to this recording: https://drive.google.com/file/d/1lDgLdziVpiHHnuWMxSoFj-Nghbj2kk9B/view?usp=sharing

Caylorman
Generally recording from Northeast Indiana
Kenwood TS-570D, SDRPlay RSP2, 107' longwire @ 30'
QSL's appreciated, caylorman<at>gmail.com

Offline CoolAM Radio

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Re: Need help on multi-tone signal ID
« Reply #3 on: August 04, 2020, 0619 UTC »
Have you already tried

https://www.rtl-sdr.com/shazam-style-automatic-signal-identification-via-the-sigidwiki-database/


André
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Offline caylorman

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Re: Need help on multi-tone signal ID
« Reply #4 on: August 04, 2020, 1822 UTC »
Yeah.  The closest thing I think it sounds like is Serdolik, but to my ear it still sounds off in its operation. 
Generally recording from Northeast Indiana
Kenwood TS-570D, SDRPlay RSP2, 107' longwire @ 30'
QSL's appreciated, caylorman<at>gmail.com