pamdemod

Pulse amplitude demodulation

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.

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.

Examples

Demodulate Noiseless 8-PAM Signal

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

Demodulate Noisy 8-PAM Signal

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)

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

Y — Pulse amplitude modulated signal

scalar | vector | matrix

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

M — Modulation order

positive integer power of two

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

Data Types: single | double

initphase — Initial phase

0 (default) | scalar | []

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

Data Types: single | double

symorder — Symbol mapping order for demodulation

"bin" (default) | "gray"

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

Z — Demodulated input signal

scalar | vector | matrix

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

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

Version History

Introduced before R2006a