Communications Blockset    
MSK Demodulator Baseband

Demodulate MSK-modulated data

Library

CPM, in Digital Baseband sublibrary of Modulation

Description

The MSK Demodulator Baseband block demodulates a signal that was modulated using the minimum shift keying method. The input is a baseband representation of the modulated signal. The Phase offset parameter is the initial phase of the modulated waveform.

Traceback Length and Output Delays

Internally, this block creates a trellis description of the modulation scheme and uses the Viterbi algorithm. The Traceback length parameter, D, in this block is the number of trellis branches used to construct each traceback path. D influences the output delay, which is the number of zero symbols that precede the first meaningful demodulated value in the output.

Inputs and Outputs

The input can be either a scalar or a frame-based column vector. If the Output type parameter is set to Integer, then the block produces values of 1 and -1. If the Output type parameter is set to Bit, then the block produces values of 0 and 1.

Processing an Upsampled Modulated Signal

The input signal can be an upsampled version of the modulated signal. The Samples per symbol parameter is the upsampling factor. It must be a positive integer. For more information, see Upsampled Signals and Rate Changes in Using the Communications Blockset.

Dialog Box

Output type
Determines whether the output consists of bipolar or binary values.
Phase offset (rad)
The initial phase of the modulated waveform.
Samples per symbol
The number of input samples that represent each modulated symbol.
Traceback length
The number of trellis branches that the Viterbi Decoder block uses to construct each traceback path.

Pair Block

MSK Modulator Baseband

See Also

CPM Demodulator Baseband, Viterbi Decoder

References

[1]  Anderson, John B., Tor Aulin, and Carl-Erik Sundberg. Digital Phase Modulation. New York: Plenum Press, 1986.


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