pamdemod

Pulse amplitude demodulation

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Syntax

Z = pamdemod(Y,M)
Z = pamdemod(Y,M,initphase)
Z = pamdemod(Y,M,initphase,symorder)

Description

Z = pamdemod(Y,M) applies pulse amplitude demodulation to the pulse amplitude modulated signal, Y, of order M and returns the demodulated input signal.

example

Z = pamdemod(Y,M,initphase) specifies the initial phase of the modulated signal in radians.

Z = pamdemod(Y,M,initphase,symorder) specifies the symbol mapping order for the demodulation.

example

Examples

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Open Live Script

Demodulate a noiseless pulse amplitude modulated signal of order 8. Verify that the input data symbols match the demodulated symbols.

Generate random 8-ary data symbols.

M = 8;
dataIn = randi([0 M-1],100,1);

Apply pulse amplitude modulation (PAM) to the generated data.

modData = pammod(dataIn,M);

Apply pulse amplitude demodulation to the modulated data.

demodData = pamdemod(modData,M);

Compare the first five symbols.

[dataIn(1:5) demodData(1:5)]
ans = 5×2

     6     6
     7     7
     1     1
     7     7
     5     5

Determine the number of symbol errors in the demodulated data.

symErrors = symerr(dataIn,demodData)
symErrors = 
0
Open Live Script

Demodulate a noisy pulse amplitude modulated signal of order 8.

M = 8;
dataIn = randi([0 M-1],1000,1);

Apply pulse amplitude modulation (PAM) to the generated data. Employ a Gray-coded symbol mapping order for the modulation.

modData = pammod(dataIn,M,0,"gray");

Pass the modulated data through an additive white Gaussian noise channel. Set the signal-to-noise ratio to 8 dB. 

noisyData = awgn(modData,M);

Display the noisy PAM constellation.

scatterplot(noisyData)

Figure Scatter Plot contains an axes object. The axes object with title Scatter plot, xlabel In-Phase, ylabel Quadrature contains a line object which displays its values using only markers. This object represents Channel 1.

Apply pulse amplitude demodulation to the noisy modulated data.

demodData = pamdemod(noisyData,M,0,"gray");

Determine the number of symbol errors in the demodulated data.

symErrors = symerr(dataIn,demodData)
symErrors = 
1

Input Arguments

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

Data Types: single | double
Complex Number Support: Yes

Modulation order, specified as a positive integer power of two.

Data Types: single | double

Initial phase of the modulated signal in radians, specified as a scalar.

Data Types: single | double

Symbol mapping order for the demodulation, specified as one of these options.

  • "bin" — Use a binary-coded mapping order.

  • "gray" — Use a Gray-coded mapping order.

The symorder argument specifies how the function assigns binary vectors to corresponding integers.

Data Types: char | string

Output Arguments

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Demodulated input signal, returned as a scalar, vector, or matrix of integers in the range [0, M–1]. Z is of the same length as Y.

Data Types: double | single

Extended Capabilities

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

Version History

Introduced before R2006a

See Also

Functions

Blocks

Topics