function signal_out = awgn_alpha_d_channel(signal_in, options)
%AWGN_ALPHA_D_CHANNEL Apply a 1 + alpha*D FIR channel followed by AWGN.

    arguments
        signal_in
        options.alpha (1,1) double = 0
        options.delay_samples (1,1) double {mustBeInteger, mustBePositive} = 1
        options.snr_dB (1,1) double = 20
        options.randkey = []
    end

    signal_out = signal_in;

    taps = zeros(1, options.delay_samples + 1);
    taps(1) = 1;
    taps(end) = options.alpha;

    signal_out.signal = filter(taps, 1, signal_in.signal, [], 1);

    if isa(signal_out, 'Signal')
        desc = sprintf('1 + alpha*D channel with alpha %.4f and delay %d samples', ...
            options.alpha, options.delay_samples);
        meta = struct( ...
            'alpha', options.alpha, ...
            'delay_samples', options.delay_samples);
        signal_out = signal_out.logbookentry(desc, meta);
    end

    signal_out = awgn_channel(signal_out, ...
        "snr_dB", options.snr_dB, ...
        "randkey", options.randkey);
end