gen_cpfsk_sig.m

这是一个连续相位调制的程序

function [src_data, mod_sig] = gen_cpfsk_sig(info_sym_num, tail_sym_num, h, m, Ns)

% sqwang's source code, used for academic research, not commerce.
% [src_data, mod_sig] = gen_cpfsk_sig(info_sym_num, tail_sym_num, h, m, Ns)
% h: Modulation index
% m: Size of modulation alphabet set
% Ns: the number of sample per symbol

sym_num_per_slot = info_sym_num + tail_sym_num;
coded_sym = zeros(sym_num_per_slot, 1);
output_sampl_num = 1 + sym_num_per_slot * Ns;          % Increment 1 for initial modulation phase

src_data = randint(info_sym_num, 1, m);

coded_sym(1 : info_sym_num) = src_data;
coded_sym(end) = mod(m - mod(sum(2 * src_data - m + mod(info_sym_num - 1, 2)) - m, 2 * m)/2, m);

% CPFSK modulation
acc_phas = zeros(output_sampl_num, 1);
for i = 2 : output_sampl_num
    acc_phas(i) = acc_phas(i - 1) + (2 * coded_sym(fix((i + Ns - 2)/Ns)) - m + 1)/Ns;
end
mod_sig = exp(j * pi * h * acc_phas);

% Get rid of initial modulation phase signal
mod_sig(1) = [];