Demodulate using MSK method and the Viterbi algorithm
The comm.MSKDemodulator object demodulates a signal that was modulated using the minimum shift keying method. The object expects the input signal to be a baseband representation of a coherent modulated signal with no precoding. The initial phase offset property sets the initial phase of the modulated waveform.
To demodulate a signal that was modulated using minimum shift keying:
Define and set up your MSK demodulator object. See Construction.
Call step
to demodulate the signal
according to the properties of comm.MSKDemodulator
.
The behavior of step
is specific to each object in
the toolbox.
Note
Starting in R2016b, instead of using the step
method
to perform the operation defined by the System object™, you can
call the object with arguments, as if it were a function. For example, y
= step(obj,x)
and y = obj(x)
perform
equivalent operations.
H = comm.MSKDemodulator
creates a demodulator System object, H
.
This object demodulates the input minimum shift keying (MSK) modulated
data using the Viterbi algorithm.
H = comm.MSKDemodulator(
creates
an MSK demodulator object, Name
,Value
)H
, with each specified
property set to the specified value. You can specify additional namevalue
pair arguments in any order as (Name1
,Value1
,...,NameN
,ValueN
).

Output data as bits Specify whether the output consists of groups of bits or integer
values. The default is When you set this property to When you set the 

Initial phase offset Specify the initial phase offset of the input modulated waveform
in radians as a real, numeric scalar value. The default is 

Number of samples per input symbol Specify the expected number of samples per input symbol as a
positive, integer scalar value. The default is 

Traceback depth for Viterbi algorithm Specify the number of trellis branches that the Viterbi algorithm
uses to construct each traceback path as a positive, integer scalar
value. The default is 

Data type of output Specify the output data type as one of When you set the 
step  Demodulate using MSK method and the Viterbi algorithm 
This object implements the algorithm, inputs, and outputs described on the MSK Demodulator Baseband block reference page. The object properties correspond to the block parameters. For MSK the phase shift per symbol is π/2, which is a modulation index of 0.5.