This
waveform is an MFSK-7 running at 200 baud, the seven tones are
400 Hz spaced. The ACF is 350 mSec then 70 bits long. Looking at its frame (pic. 3,4,5) it
seems that 7 bits transport something like data while the other 63 bits
have a constant sequence (Sync?).
It looks like a "selective
call" and the only think that I could find in the web is a reference to
the "AirCal": an MFSK 7 tone system by the old Racal (!?): http://www.scancat.com/rvw-faqc.html
Well, Racal was
taken over by Thomson-CSF and now it's Thales. Although Thales has
continued part of the former Racal product line, most products have
gradually disappeared along with the name 'Racal' itself.
The signal was caught by KarapuZ on 10150.0 KHz on USB, around 1540z on 15 July (present year): it's available on request for your further analysis: just email me.
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| pic.1 - speed |
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| pic.2 grid |
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| pic.3 ACF |
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| pic.4 frame structure |
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| pic.5 FSK demod |
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