Wavecom W74PC V8.7.0 - Manual (Page 265)

WAVECOM Decoder W74PC, W-PCI/e, W-CODE, W-CLOUD Manual V8.7.0 Transmission Modes
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Layer Constraints
Layer 2 Logical channels:
User plane, traffic channels:
 Circuit mode not supported
Control plane, control channels:
 All channels except Access Assignment Channel (AACH)
Protocol Data Units (PDU):
 Only downlink PDUs supported
Layer 3 At layer 3, control plane PDUs are user selectable
THROB and THROBX
THROB and THROBX are two MFSK modes, created by Lionel Sear, G3PPT. THROBX is an evolution of
THROB.
Parameter Value
Frequency range HF
Operation modes Simplex
Modulation MFSK
Symbol rate 1, 2 or 4 Bd
Receiver settings USB or LSB
Input format(s) AF, IF
Additional Info 9 or 11 tones are used
THROB uses 9 frequencies. 1 or 2 tones are sent at the same time. The frequencies are spaced 8 Hz at 1
and 2 baud, and 16 Hz at 4 baud. This allows for 45 characters. The THROB alphabet is slightly larger, so
some characters are encoded using a shift character first.
THROBX uses 11 frequencies, spaced 7.8125 Hz apart. 2 tones are sent at the same time, which allows for
55 characters. W-CODE also supports THROBX with 4 baud, which is a non-standard mode, but is sup-
ported in the FLDIGI software.
Tuning
Since the spacing between two tones is only about 8 Hz, the tuning of the mode must be very exact. Put
the middle tuning cursor to the center of the signal. The center of the MFSK signal can be measured by
turning on the “Peak Hold” setting in the FFT tuning window.