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Appendix for Audio Localization Project
Summary: This section contains a few important links, the code that we used for the project, and the project executable files.
Matlab Code
- new_sim2:
function new_sim2(theta_true) % Values, Vectors, and a Matrix %theta_true = pi./2; degree = 32; c = 346.287; % speed of sound in air N = 150; % length of the sample buffer Fs = 48000; % sampling frequency f = 500; % frequency of sine wave M = 2; % number of microphones dist = .1; t = [0:N-1]./Fs; % time axis m = (M-1)./2; % array center x = dist.*[-m:m]; % microphone location on the x axis omega = 2*pi*f; % commonly used value theta_test = [1:2:2*degree-1]*pi/(2*degree); % test vector of theta values %theta_test = pi./2; divisor = degree/8; % region divisor length_t = length(theta_test); % length of the delay vector A = zeros(1,length_t); % initialize A vector delay_true = x.*cos(theta_true)./c; % actual delay delay_test = x'*cos(theta_test)./c; % test matrix of delay values samples = round(2.*delay_test*Fs)./2; % number of samples to shift in testing index = samples - ones(M,1)*min(samples) + 1; % Signal Simulation for j = 1:M y(j,:) = sin(omega*(t-delay_true(j))); end % Region Approximation for i = [1:length_t] for j = [1:M] y_delay(j,:) = y(j,[index(j,i)+50:index(j,i)+100]); %delay y1 by the 1,i value using index end z = sum(y_delay); A(i) = sum(z.^2); end aa = find(A == max(A)); region = floor(aa(1)./divisor) theta_range = [region-1 region]*pi/8; if(0) figure plot(theta_test/pi,A) end - sim_input3:
function [region,theta_range] = sim_input3(theta_true,degree) % Values, Vectors, and a Matrix c = 346.287; % speed of sound in air N = 150; % length of the sample buffer Fs = 44100; % sampling frequency f = 500; % frequency of sine wave M = 2; % number of microphones %dist = .32; % distance between microphones dist = .5; t = [0:N-1]./Fs; % time axis m = (M-1)./2; % array center x = dist.*[-m:m]; % microphone location on the x axis cutoff = 50; % cutoff frequency of filter omega = 2*pi*f; % commonly used value theta_test = [1:2:2*degree-1]*pi/(2*degree); % test vector of theta values divisor = degree/8; % region divisor length_t = length(theta_test); % length of the delay vector A = zeros(1,length_t); % initialize A vector B = fir1(40,cutoff/Fs,'low'); % lowpass filter delay_true = x.*cos(theta_true)./c; % actual delay delay_test = x'*cos(theta_test)./c; % test matrix of delay values samples = round(2.*delay_test*Fs)./2; % number of samples to shift in testing index = samples - ones(M,1)*min(samples) + 1; cos_base = cos(omega*t(1:N)); sin_base = sin(omega*t(1:N)); SNR = 1000; noise1 = randn(1,N)/SNR; noise2 = randn(1,N)/SNR; % Signal Simulation y1 = sin(omega*(t-delay_true(1))) + noise1; y2 = sin(omega*(t-delay_true(2))) + noise2; % Region Approximation for i = [1:length_t] y1_sample = y1(index(1,i):index(1,i)+40); %delay y1 by the 1,i value using index y2_sample = y2(index(2,i):index(2,i)+40); z = y1_sample + y2_sample; z_cos = z.*cos_base(1:41); z_sin = z.*sin_base(1:41); z_cos_filter = sum(fliplr(z_cos).*B); z_sin_filter = sum(fliplr(z_sin).*B); A(i) = z_sin_filter^2 + z_cos_filter^2; end % figure % plot(theta_test,A); % title(theta_true) aa = find(A == max(A)); region = floor(aa(1)./divisor); if(0) theta_range = [region-1 region]*pi/8; figure plot(theta_test/pi,A) end
C Code
- index.h:
short index[2][32] = { {0x0001, 0x0001, 0x0001,0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0002, 0x0003, 0x0004, 0x0005, 0x0006, 0x0008, 0x0009, 0x000A, 0x000A, 0x000B, 0x000C, 0x000D, 0x000D, 0x000D, 0x000E, 0x000E}, {0x000E, 0x000E, 0x000D,0x000D, 0x000D, 0x000C, 0x000B, 0x000A, 0x000A, 0x0009, 0x0008, 0x0006, 0x0005, 0x0004, 0x0003, 0x0002, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001, 0x0001} }; - loop_intr_pcm2.c:
#include "index.h" #define N 100 //sample buffer length #define N2 128 //averaging buffer length #define DEGREE 32 //number of theta test values to try #define SUMSAMP 70 //number of theta test values to try float Fs = 16000.0; //irrelevant since jumper in 3-4 int* lights = (int*)0x90080000; short buffer1[N] = {0}; short buffer2[N] = {0}; int buffer3[N2] = {0}; int buf_full = 0; int buf_index = 0; interrupt void c_int12() //McBSP1 receive ISR { int sample = input_leftright_sample(); buffer1[buf_index] = (short)(sample >> 16); buffer2[buf_index] = (short)sample; buf_index++; if(buf_index == N) { buf_index = 0; buf_full = 1; } return; //return from interrupt } void main() { int i; int j; int k = 0; int z, test_amp; int region; int out; int sum = 0; int max_theta_index = 0; int max_amplitude = -1; for(k=0;k<N2;k++) buffer3[k] = 0; k = 0; comm_intr(); //init DSK, codec, McBSP while(1) { if(buf_full) { buf_full = 0; max_amplitude = -1; for(i=0; i<DEGREE; i++) { test_amp = 0; for(j=0; j<SUMSAMP; j++) { z = buffer1[index[0][i]+j] + buffer2[index[1][i]+j]; test_amp += (z * z) >> 15; } if(test_amp > max_amplitude) { max_amplitude = test_amp; max_theta_index = i; } } region = max_theta_index >> 2; sum -= buffer3[k]; buffer3[k++] = region; sum += region; if(k == N2) { k = 0; out = sum >> 7; /*if(out > 3) out = 0; else out = 7;*/ *lights = out << 24; } } } } - vectors_11.asm:
*Vectors_11.asm Vector file for interrupt-driven program .ref _c_int12 ;ISR used in C program .ref _c_int00 ;entry address .sect "vectors" ;section for vectors RESET_RST: mvkl .S2 _c_int00,B0 ;lower 16 bits --> B0 mvkh .S2 _c_int00,B0 ;upper 16 bits --> B0 B .S2 B0 ;branch to entry address NOP ;NOPs for remainder of FP NOP ;to fill 0x20 Bytes NOP NOP NOP NMI_RST: .loop 8 NOP ;fill with 8 NOPs .endloop RESV1: .loop 8 NOP .endloop RESV2: .loop 8 NOP .endloop INT4: .loop 8 NOP .endloop INT5: .loop 8 NOP .endloop INT6: .loop 8 NOP .endloop INT7: .loop 8 NOP .endloop INT8: .loop 8 NOP .endloop INT9: .loop 8 NOP .endloop INT10: .loop 8 NOP .endloop INT11: .loop 8 NOP .endloop INT12: b _c_int12 ;branch to ISR .loop 7 NOP .endloop INT13: .loop 8 NOP .endloop INT14: .loop 8 NOP .endloop INT15: .loop 8 NOP .endloop
Project Executable Files
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This work is licensed by Elizabeth Gregory and Joseph Cole under a Creative Commons Attribution License (CC-BY 1.0).
Last edited by Elizabeth Gregory on Dec 15, 2004 4:34 pm US/Central.