| function [y, mark]= sync_chirp(fs, direction) |
| |
| %% [y, mark]= sync_chirp(fs, direction) |
| % |
| % Returns a chirp signal that can be used to mark end and beginning of audio |
| % tests to syncronize input and captured output accurately. |
| % |
| % Input |
| % fs - sample rate |
| % direction - direction of frequency sweep 'up' or 'down' |
| % |
| % Output |
| % y - windowed chirp signal |
| % mark - struct with parameters for chirp |
| % |
| |
| %% |
| % Copyright (c) 2017, Intel Corporation |
| % All rights reserved. |
| % |
| % Redistribution and use in source and binary forms, with or without |
| % modification, are permitted provided that the following conditions are met: |
| % * Redistributions of source code must retain the above copyright |
| % notice, this list of conditions and the following disclaimer. |
| % * Redistributions in binary form must reproduce the above copyright |
| % notice, this list of conditions and the following disclaimer in the |
| % documentation and/or other materials provided with the distribution. |
| % * Neither the name of the Intel Corporation nor the |
| % names of its contributors may be used to endorse or promote products |
| % derived from this software without specific prior written permission. |
| % |
| % THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| % AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| % IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| % ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
| % LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| % CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| % SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| % INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| % CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| % ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| % POSSIBILITY OF SUCH DAMAGE. |
| % |
| % Author: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com> |
| % |
| |
| mark.a_db = -10; |
| mark.a = 10^(mark.a_db/20); |
| mark.fs = fs; |
| mark.t = 0.2; % Short, to not consume much test time |
| switch lower(direction) |
| case 'up' |
| mark.f0 = 200; % Should work with any speaker |
| mark.f1 = 3500; % Should work with any speaker |
| case 'down' |
| mark.f1 = 200; % Should work with any speaker |
| mark.f0 = 3500; % Should work with any speaker |
| otherwise |
| error('Parameter direction must be ''up'' or ''down'''); |
| end |
| |
| mark.n = round(mark.t*fs); |
| t_vec = (0:mark.n-1)/fs; |
| w = hanning(mark.n); |
| x = chirp(t_vec, mark.f0, mark.t, mark.f1, 'linear')'; |
| y = x .* w * mark.a; |
| |
| end |