1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
|
function [y, h] = resample( x, p, q, h )
//This function resamples in the input sequence x supplied by a factor of p/q.
//Calling Sequence
//y = resample(x, p, q)
//y = resample(x, p, q, h)
//[y, h] = resample(...)
//Parameters
//x: scalar, vector or matrix of real or complex numbers
//p: positive integer value
//q: positive integer value
//h: scalar, vector or matrix of real or complex numbers
//Description
//This is an Octave function.
//This function resamples in the input sequence x supplied by a factor of p/q. If x is a matrix, then every column is resampled.hange the sample rate of x by a factor of p/q.
//This is performed using a polyphase algorithm. The impulse response h, given as parameter 4, of the antialiasing filter is either specified or designed with a Kaiser-windowed sinecard.
//Examples
//resample(1,2,3)
//ans = 0.66667
funcprot(0);
rhs = argn(2)
lhs = argn(1)
if(rhs<3 | rhs>4)
error("Wrong number of input arguments.")
end
select(rhs)
case 3 then
if(lhs==1)
y = callOctave("resample",x,p,q)
elseif(lhs==2)
[y,h] = callOctave("resample",x,p,q)
end
case 4 then
if(lhs==1)
y = callOctave("resample",x,p,q,h)
elseif(lhs==2)
[y,h] = callOctave("resample",x,p,q,h)
end
end
endfunction
//**************************************************************************************************
//Tried to impement without callOctave but fot this it requires ufirdn function which implemented in .cc file in octave, simple implementation of upfirdn doesn't work for resample function
//**************************************************************************************************
//function [y, h] = resample( x, p, q, h )
// nargin = argn(2);
//
// [rows, columns] = size(x) ;
//
// if nargin < 3 | nargin > 4
// error("resample.sci : invalid number of inputs");
// elseif or([p q]<=0) | or([p q]~=floor([p q])),
// error("resample.sci: p and q must be positive integers");
// end
//
//// ## simplify decimation and interpolation factors
//
// great_common_divisor=gcd([p,q]);
// if (great_common_divisor>1)
// p = double(p) / double (great_common_divisor);
// q = double(q) / double (great_common_divisor);
// else
// p = double(p);
// q = double(q);
// end
//
//// ## filter design if required
//
// if (nargin < 4)
//
//// ## properties of the antialiasing filter
//
// log10_rejection = -3.0;
// stopband_cutoff_f = 1 / (2 * max (p, q));
// roll_off_width = stopband_cutoff_f / 10.0;
//
//// ## determine filter length
//// ## use empirical formula from [2] Chap 7, Eq. (7.63) p 476
//
// rejection_dB = -20.0*log10_rejection;
// L = ceil((rejection_dB-8.0) / (28.714 * roll_off_width));
//
//// ## ideal sinc filter
//
// t=(-L:L)';
// ideal_filter=2*p*stopband_cutoff_f*sinc(2*stopband_cutoff_f*t);
//
//// ## determine parameter of Kaiser window
//// ## use empirical formula from [2] Chap 7, Eq. (7.62) p 474
//
// if ((rejection_dB>=21) & (rejection_dB<=50))
// beta = 0.5842 * (rejection_dB-21.0)^0.4 + 0.07886 * (rejection_dB-21.0);
// elseif (rejection_dB>50)
// beta = 0.1102 * (rejection_dB-8.7);
// else
// beta = 0.0;
// end
//
//// ## apodize ideal filter response
//
// h=kaiser(2*L+1,beta).*ideal_filter;
//
// end
//
//// ## check if input is a row vector
// isrowvector=%F;
// if ((rows==1) & (columns>1))
// x=x(:);
// isrowvector=%T;
// end
//
//// ## check if filter is a vector
// if ~isvector(h)
// error("resample.sci: the filter h should be a vector");
// end
//
// Lx = rows;
// Lh = length(h);
// L = ( Lh - 1 )/2.0;
// Ly = ceil(Lx*p/q);
//
//// ## pre and postpad filter response
//
// nz_pre = floor(q-pmodulo(L,q));
//// hpad = prepad(h,Lh+nz_pre);
// hpad = h ;
// for i = 1:Lh+nz_pre-length(h)
// hpad = [0;hpad];
// end
//
// offset = floor((L+nz_pre)/q);
// nz_post = 0;
// while ceil( ( (Lx-1)*p + nz_pre + Lh + nz_post )/q ) - offset < Ly
// nz_post = nz_post + 1;
// end
//
// //hpad = postpad(hpad,Lh + nz_pre + nz_post);
// for i = 1:Lh + nz_pre + nz_post-length(hpad)
// hpad = [hpad;0];
// end
//
//// ## filtering
// xfilt = upfirdn(x,hpad,p,q);
// y = xfilt(offset+1:offset+Ly,:);
//
// if isrowvector,
// y=y.';
// end
//
//endfunctio
|
