Digital Signal Processing Reference
In-Depth Information
Table 6.1
Spectral
lines
for
a
pulse-shaped
modulated
carrier
oscillation
Designation
Frequency
Amplitude
Carrier oscillation
f
CR
u
HF
·
(
1
−
m)
·
(T
−
τ)/T
1st spectral line
f
CR
±
1
/T
u
HF
·
m
·
sin
(π
·
τ/T)
2nd spectral line
f
CR
±
2
/T
u
HF
·
m
·
sin
(
2
π
·
τ/T)
3rd spectral line
f
CR
±
3
/T
u
HF
·
m
·
sin
(
3
π
·
τ/T)
n
th spectral line
f
CR
±
n/T
u
HF
·
m
·
sin
(nπ
·
τ/T)
Amplitude
Time
0
t
T
Figure 6.8
Representation of the period duration
T
and the bit duration
τ
of a binary
code signal
Amplitude
Digital
signal
f
2
Time
0
t
T
2FSK modulator
HF amplitude
f
1
HF
signal
Figure 6.9
The generation of 2 FSK modulation by switching between two frequencies
f
1
and
f
2
in time with a binary code signal
6.2.2 2 FSK
In
2 frequency shift keying
the frequency of a carrier oscillation is switched between
two frequencies
f
1
and
f
2
by a binary code signal (Figure 6.9).
The carrier frequency
f
CR
is defined as the arithmetic mean of the two charac-
teristic frequencies
f
1
and
f
2
. The difference between the carrier frequency and the
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