10 August 2015

SERDOLIK Selcall


This waveform provides a 31 frequency grid, 40 Hz spaced, and 40 Baud rate (pic. 1). The signals has MFSK insertions into the sync-marker sequence
The call shown in pic. 2 ends into a sync-marker sequence and since no data follows, this could be a sort of null call. 
In pic.3 a complete session, 105 secs lasting, with the call followed by data sent in MFSK-34 mode (CROWD-36): difficult to state if this 'traffic' corresponds to user-data or to link-setup informations with the actual traffic sent in another frequency and/or mode.
The recording in pic. 4 is a more complete example: the call and the sync timing, the sending of link-setup information through MFSK-34 and then the transmission of data through the OFDM 35-tone BSPK waveform. It's interesting to note that the both the call and the MFSK-34 two initial tones exhibit a shift that is the half of the usual.

Pic. 1
Pic. 2
Pic. 3

Pic. 4

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