Rohde & Schwarz SMIQ02B - Coding; FSK Modulation; Table 2-7 Frequency Deviations for FSK Methods; Table 2-8 Possible Combination of Modulation Method and Coding

SMIQ Digital Modulation
1125.5555.03 E-92.89
2.10.1.3 FSK Modulation
For FSK modulation, frequency shifts are assigned to the modulation symbols. The modulation index h
of this digital frequency modulation is determined by
h
f
f
Symb
=⋅2 ∆ /
The symbol rate f
SYMB
can be freely set to a maximum of 2.5 Msymb/s for all FSK modulations. With
GMSK selected, the frequency deviation
∆
f
(FSK deviation) cannot be set since the modulation index is
fixed to a value of h = 0.5. The following table shows the assignment of modulation symbols and
frequency deviations for the different FSK methods.
Table 2-7 Frequency deviations for FSK methods
Mod. symbol 2FSK, GFSK MSK, GMSK 4FSK APCO
0
−∆
f
−∆
f
−∆
f
+∆
f
/3
1
+∆
f
+∆
f
−∆
f
/3 +∆
f
10 - -
+∆
f
/3 −∆
f
/3
11 - -
+∆
f
−∆
f
All FSK modulation methods can be combined with COS, SQR_COS, GAUSS and BESSEL baseband
filters. A combination with IS-95 filters is not permissible.
2.10.1.4 Coding
Modulation symbols are coded directly before an assignment of I and Q values or frequency shifts.
Coding is thus directly related with modulation methods which is the reason why codings are not freely
combinable with modulation methods. The following table shows which combinations are possible.
Table 2-8 Possible combination of modulation method and coding
Coding Selection CODING Combinable with MOD TYPE Example of use
Differential coding DIFF all except for 256QAM
Gray + differential
coding
GRAY+DIFF all except for 256QAM D8PSK for VDR
GSM differential coding GSM FSK, GFSK, GMSK Mobile radio standard GSM
π/4DQPSK differential
coding
NADC; PDC;..
π/4DQPSK
Mobile radio standards NADC,
PDC, PHS, APCO25, TFTS,
TETRA
Phase differential coding INMARSAT QPSK ISAT Satellite system INMARSAT-M
Phase differential coding PHASE DIFF 16 , 32 , 64 , 256 QAM DVB in line with ETS 300429
VDL coding VDL 8PSK VHF Digital Link
The effect of differential coding on π/4DQPSK has been described in section 'Modulation π/4DQPSK'.
Common coding types are listed in the following table.