MSK (Minimum Shift Keying) CML Microcircuits, MSK (Minimum Shift Keying) Datasheet - Page 4

• Manufacturer Part Number: MSK (Minimum Shift Keying)
• Description: Minimum Shift Keying and its Application to Wireless Data Transmission
• Manufacturer: CML Microcircuits

MSK and its Application to Wireless Data Transmission
Where, nT
modulating signal (NRZ binary data) has no impulses, the modulated carrier e(t) will not have phase discontinuities. A
general representation for CPFSK modulator is shown in Figure 2.
modulation systems (e.g. FM) K is proportional to the peak frequency deviation of the VCO. For CPFSK, the modulation
m(t) is NRZ data and
Where, f
The term f
for , nT
For MSK, h = 0.5 so (14) can be written as
for , nT
Consequently, if S
When S
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Looking at the term K in equation (12)—referred to as a constant of proportionality earlier—for constant envelope
n
T = symbol or bit period
f
f
1
2
d
is -1 , the frequency of the carrier is shifted lower to
t < (n+1)T .
t < (n+1)T .
= logic zero ( S
= logic one ( S
d
=
T is commonly known as the modulation index h . Substituting 2 h for K in (12) yields
t < (n+1)T and
f
2
- f
1
n
is +1 , the frequency of the carrier is shifted higher to
n
n
=+1 ).
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=-1 )
n
is adjusted according to the phase of the previous symbol
DATA IN
BINARY
NRZ
e t
e t
( )
( )
Figure 2:CPFSK generation.
A
A
m(t)
K
C
C
f
f
1
2
n
n
2
f
f
cos[
cos[
C
C
f T
4
d
cos
2
4
2
VCO
4
1
1
.
T
T
f t
C
.
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.
f t
t)
C
hS
T
4
S
e(t)
T
n
n
t
t
OUTPUT
FSK
n
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]
n
]
n-1
. As a result, if the
Doc. # 20830084.001
(13)
(14)
(15)
(16)
(17)
APPLICATION