mskdemod

Minimum shift keying demodulation

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Syntax

Z = mskdemod(Y,nsamp)
Z = mskdemod(Y,nsamp,dataenc)
Z= mskdemod(Y,nsamp,dataenc,initphase)
Z= mskdemod(Y,nsamp,dataenc,initphase,initstate)
[Z,phaseout] = mskdemod(___)
[Z,phaseout,stateout] = mskdemod(___)

Description

Z = mskdemod(Y,nsamp) applies differentially encoded minimum shift keying (MSK) demodulation to the MSK modulated signal, Y, and returns the demodulated input signal.

Z = mskdemod(Y,nsamp,dataenc) specifies the data encoding method for MSK.

Z= mskdemod(Y,nsamp,dataenc,initphase) specifies the initial phase of the MSK demodulator.

Z= mskdemod(Y,nsamp,dataenc,initphase,initstate) specifies the initial state of the MSK demodulator.

[Z,phaseout] = mskdemod(___) returns the final phase of Y for any of the input argument combinations in the previous syntaxes.

[Z,phaseout,stateout] = mskdemod(___) returns the sample values corresponding to the last symbol of the previously received signal for any of the input argument combinations in the previous syntaxes.

example

Examples

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Open Live Script

Demodulate a noisy minimum shift keying (MSK) signal. Display the number of bit errors.

Set the number of samples per symbol for the MSK signal to 16.

nsamp = 16;

Initialize the simulation parameters.

numerrs = 0; 
modPhase = zeros(1,2);    
demodPhase = zeros(1,2);  
demodState = complex(zeros(nsamp,2));

The main processing loop includes these steps:

  1. Generate binary data.

  2. Apply MSK modulation to the data.

  3. Pass the signal through an additive white Gaussian noise channel.

  4. Demodulate the noisy MSK signal.

  5. Determine the number of bit errors.

for iRuns = 1:20
    txData = randi([0 1],100,2);
    [modSig,modPhase] = mskmod(txData,nsamp,[],modPhase);
    rxSig = awgn(modSig,20,'measured');
    [rxData,demodPhase,demodState] = mskdemod(rxSig,nsamp,[],demodPhase,demodState);
    numerrs = numerrs + biterr(txData,rxData);
end

Display the number of bit errors.

numerrs
numerrs = 
0

Input Arguments

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MSK modulated signal, specified as a vector or matrix. If Y is a matrix, the function processes the columns independently.

Data Types: single | double
Complex Number Support: Yes

Number of samples per MSK symbol, specified as a positive integer.

Data Types: single | double

Data encoding method, specified as one of these options.

  • "diff" — Use differentially encoded MSK.

  • "nondiff" — Use nondifferentially encoded MSK.

  • [] — Use to avoid overriding the default value.

Initial phase of the MSK demodulator in radians, specified as a scalar or row vector of integer multiples of pi/2. The length of initphase equals the number of channels in Y.

Data Types: single | double

Initial state of the demodulator, specified as an nsamp-by-1 column vector or nsamp-by-C matrix. C is the number of channels in Y. The initstate argument contains the last symbol of the previously received signal.

Data Types: single | double

Output Arguments

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Demodulated input signal, returned as a column vector or matrix of binary values.

Data Types: double | single

Final phase of the MSK modulated signal, returned as a scalar or row vector in which each value is 0, pi/2, pi, or 3*pi/2. The output argument phaseout has the same dimensions as the input argument initphase.

Data Types: single | double

Sample values corresponding to the last symbol of the previously received signal, returned as an nsamp-by-1 column vector or nsamp-by-C matrix. The output argument stateout has the same dimensions as the input argument initstate.

Data Types: single | double

References

[1] Pasupathy, S. “Minimum Shift Keying: A Spectrally Efficient Modulation.”IEEE® Communications Magazine (July, 1979): 14–22.

Extended Capabilities

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C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced before R2006a

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See Also

Functions

Objects

Blocks

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