comm.GMSKDemodulator
Demodulate GMSK-modulated signal using Viterbi algorithm
Description
The comm.GMSKDemodulator
System object™ uses a Viterbi algorithm to demodulate a signal that was modulated using the
Gaussian minimum shift keying (GMSK) method. The input is a baseband representation of the
modulated signal.
To demodulate a GMSK-modulated signal using the Viterbi algorithm:
Create the
comm.GMSKDemodulator
object and set its properties.Call the object with arguments, as if it were a function.
To learn more about how System objects work, see What Are System Objects?
Creation
Description
creates a demodulator System object that demodulates the input GMSK-modulated data by using the Viterbi
algorithm.gmskdemodulator
= comm.GMSKDemodulator
sets properties using one or more name-value pairs. For example,
gmskdemodulator
= comm.GMSKDemodulator(Name
,Value
)gmskdemodulator = comm.GMSKDemodulator('PulseLength',6)
specifies the
length of the Gaussian pulse shape as 6 symbol intervals.
Properties
Usage
Syntax
Description
Input Arguments
Output Arguments
Object Functions
To use an object function, specify the
System object as the first input argument. For
example, to release system resources of a System object named obj
, use
this syntax:
release(obj)
Examples
Algorithms
The BandwidthTimeProduct
property represents bandwidth multiplied by time. Use this property to reduce the bandwidth at
the expense of increased intersymbol interference. The PulseLength
property measures the
length of the Gaussian pulse shape in symbol intervals. These equations define the frequency
pulse shape. Bb represents the bandwidth of the
pulse and T is the symbol durations. Q(t) is the
complementary cumulative distribution function.
For this System object, an input symbol of 1 causes a phase shift of π/2 radians, which corresponds to a modulation index of 0.5.
References
[1] Anderson, John B., Tor Aulin, and Carl-Erik Sundberg. Digital Phase Modulation. New York: Plenum Press, 1986.
Extended Capabilities
Version History
Introduced in R2012a