Brief Description of Vector Signal Analysis
R&S
®
FSV-K70
34
Operating Manual 1176.7578.02 ─ 09
2.3.7 Minimum Shift Keying (MSK)
MSK modulation causes modulation-dependent phase shifts of +/- 90° which can be
shown in an Constellation I/Q diagram. As with PSK, demodulation is performed by
evaluation of the phase positions.
Table 2-14: MSK (NATURAL)
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB)
0
1
Phase shift
-90°
+90°
Table 2-15: MSK (GSM)
Logical symbol mapping
Modulation symbol (binary indication: MSB, LSB)
0
1
Phase shift
+90°
-90°
Figure 2-29: MSK (for GSM and NATURAL) and DMSK Constellation Diagram including the symbol
mapping
Similar to PSK, differential coding can also be used with MSK. In this case, too, the
information is represented by the transition of two consecutive symbols. The block dia-
gram of the coder is shown below.
Figure 2-30: DMSK: differential encoder in the transmitter
d
i
input symbol {0;1} of differential encoder
d
i-1
input symbol delayed by the symbol period Ts
Symbol Mapping
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