双音多频拨号 matlab

双音多频拨号（DTMF）是一种电话拨号系统，它使用两个音频信号以不同频率组合来表示数字、字母和符号。在 MATLAB 中，可以使用以下代码生成 DTMF 信号：

Fs = 8000; % 采样率为8000Hz
durations = [0.15, 0.15]; % 每个数字的持续时间为0.15秒
keys = ['1', '2', '3', '4', '5', '6', '7', '8', '9', '*', '0', '#']; % DTMF键
freqs = [697, 770, 852, 941, 1209, 1336, 1477]; % DTMF频率
DTMF = zeros(1, Fs*sum(durations)); % 初始化DTMF信号

for i = 1:length(keys)
    % 计算当前键的频率
    if keys(i) == '1'
        freq1 = freqs(1);
        freq2 = freqs(5);
    elseif keys(i) == '2'
        freq1 = freqs(1);
        freq2 = freqs(6);
    elseif keys(i) == '3'
        freq1 = freqs(1);
        freq2 = freqs(7);
    elseif keys(i) == '4'
        freq1 = freqs(2);
        freq2 = freqs(5);
    elseif keys(i) == '5'
        freq1 = freqs(2);
        freq2 = freqs(6);
    elseif keys(i) == '6'
        freq1 = freqs(2);
        freq2 = freqs(7);
    elseif keys(i) == '7'
        freq1 = freqs(3);
        freq2 = freqs(5);
    elseif keys(i) == '8'
        freq1 = freqs(3);
        freq2 = freqs(6);
    elseif keys(i) == '9'
        freq1 = freqs(3);
        freq2 = freqs(7);
    elseif keys(i) == '*'
        freq1 = freqs(4);
        freq2 = freqs(5);
    elseif keys(i) == '0'
        freq1 = freqs(4);
        freq2 = freqs(6);
    elseif keys(i) == '#'
        freq1 = freqs(4);
        freq2 = freqs(7);
    end
    
    % 生成当前键的DTMF信号
    t = linspace(0, durations(1), durations(1)*Fs);
    s1 = sin(2*pi*freq1*t);
    s2 = sin(2*pi*freq2*t);
    signal = s1 + s2;
    DTMF(1, (i-1)*Fs*durations(1)+1:i*Fs*durations(1)) = signal;
    
    % 暂停一段时间
    pause(durations(2));
end

% 播放DTMF信号
soundsc(DTMF, Fs);

上述代码首先定义了采样率和每个数字的持续时间。然后，定义了 DTMF 键和相应的频率。使用循环生成每个键的 DTMF 信号，其中根据键的类型选择相应的频率。最后，将所有 DTMF 信号连接在一起并播放。