test/test_utils/mix_chirp.m

function  test = mix_chirp(test)

%%
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% Author: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>
%

%% Adjust tone length to integer number of samples
test.nt = round(test.cl*test.fs); % Make number of samples per tone
test.tl = test.nt/test.fs;        % an integer by adjusting tl.

%% Test start and end marker tones
[h1, mark_start] = sync_chirp(test.fs, 'up');
[h2, mark_end] = sync_chirp(test.fs, 'down');
test.mark_t = mark_start.t;
test.mark_a = mark_start.a;
test.mark_a_db = mark_start.a_db;
test.ts = mark_start.t;

%% Idle time to start and end
test.idle_t = 0.5;
n_idle = round(test.fs*test.idle_t);
t_idle = n_idle/test.fs;
x = zeros(test.nt + mark_start.n + mark_end.n +2*n_idle, test.nch, 'int32');

%% Add markers
idx1 = n_idle+1;
idx2 = length(x)-n_idle-mark_end.n;
for ch=test.ch
        x(idx1:idx1+mark_start.n-1, ch) = dither_and_quantize(h1, test.bits_in);
        x(idx2:idx2+mark_end.n-1, ch) = dither_and_quantize(h2, test.bits_in);
end

%% Dither also idle parts
x(1:n_idle) = dither_and_quantize(zeros(n_idle,1), test.bits_in);
x(end-n_idle+1:end) = dither_and_quantize(zeros(n_idle,1), test.bits_in);

%% Add Chirp
i1 = n_idle+mark_start.n+1;
i2 = i1+test.nt-1;
fprintf('Mixing %.1f dBFS chirp ...\n', test.a_db);
tc = ((1:round(test.cl*test.fs))-1)/test.fs;
s = test.a * chirp(tc, test.f_min, test.tl, test.f_max, 'linear', 90);
sign = 1;
for ch=test.ch
        x(i1:i2, ch) = dither_and_quantize(sign * s, test.bits_in);
	sign = -sign;
end

test.signal = x;

%% Output
fprintf('Writing output data file %s...\n', test.fn_in);
write_test_data(x, test.fn_in, test.bits_in, test.fmt);
fprintf('Done.\n')

end