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This FSK transmission was copied on 6330.8 (cf) at 1128z: shift is clearly 100Hz while some problems arise when measuring the speed. Indeed, the measurement of the speed based on FFT may fail in case of non-integer number of bits as in Baudot/ITA2 code where the stop bit lasts 1.5 bit: in this case SA assumes an integer number of bits, so it prints out a value of 53.47 Baud (Fig. 1)
This FSK transmission was copied on 6330.8 (cf) at 1128z: shift is clearly 100Hz while some problems arise when measuring the speed. Indeed, the measurement of the speed based on FFT may fail in case of non-integer number of bits as in Baudot/ITA2 code where the stop bit lasts 1.5 bit: in this case SA assumes an integer number of bits, so it prints out a value of 53.47 Baud (Fig. 1)
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| Fig. 1 |
In such cases the speed shall be measured using the "raster" tool of SA (Fig. 2): the structure of the frame is 7.5 bit (1 bit start, 5 bit of data and 1.5 stop bit) and the time line is 299.4 msec for 15 bit that makes a speed of 50 Baud.
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| Fig. 2 |
Baudod decoders work fine and print out the content of the message after the RYRY sequence, in this case: ZHGD DE N4O4 QRK ? The user is not identified, probably Russian Military.
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| Fig. 4 |
https://yadi.sk/d/K_eEO7cT3QFLLU