1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_hft248d_f64.c
4 * Description: Floating-point (f64) Hft248d window
5 *
6 * $Date: 14 December 2022
7 * $Revision: v1.15.0
8 *
9 * Target Processor: Cortex-M and Cortex-A cores
10 * -------------------------------------------------------------------- */
11 /*
12 * Copyright (C) 2010-2022 ARM Limited or its affiliates. All rights reserved.
13 *
14 * SPDX-License-Identifier: Apache-2.0
15 *
16 * Licensed under the Apache License, Version 2.0 (the License); you may
17 * not use this file except in compliance with the License.
18 * You may obtain a copy of the License at
19 *
20 * www.apache.org/licenses/LICENSE-2.0
21 *
22 * Unless required by applicable law or agreed to in writing, software
23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
25 * See the License for the specific language governing permissions and
26 * limitations under the License.
27 */
28
29 #include "dsp/window_functions.h"
30 #include "dsp/fast_math_functions.h"
31 #include <math.h>
32 /**
33 @ingroup groupWindow
34 */
35
36
37
38
39 /**
40 @addtogroup WindowFlat
41 @{
42 */
43
44
45 /**
46 @ingroup WindowHFT248D
47 */
48
49 /**
50 @brief Hft248d window generating function (f64).
51 @param[out] pDst points to the output generated window
52 @param[in] blockSize number of samples in the window
53 @return none
54
55 @par Parameters of the window
56
57 | Parameter | Value |
58 | ------------------------------------: | -----------------: |
59 | Peak sidelobe level | 248.4 dB |
60 | Normalized equivalent noise bandwidth | 5.6512 bins |
61 | 3 dB bandwidth | 5.5567 bins |
62 | Flatness | 0.0009 dB |
63 | Recommended overlap | 84.1 % |
64
65 Included in CMSIS-DSP with authorization from professor
66 Gerhard Heinzel.
67
68 @par Original article:
69 Spectrum and spectral density estimation by the Discrete Fourier
70 transform (DFT), including a comprehensive list of window
71 functions and some new
72 flat-top windows.
73
74 @par Authors:
75 G. Heinzel, A. Rudiger and R. Schilling,
76 Max-Planck-Institut fur Gravitationsphysik
77 (Albert-Einstein-Institut)
78 Teilinstitut Hannover
79 */
80
81
82
arm_hft248d_f64(float64_t * pDst,uint32_t blockSize)83 void arm_hft248d_f64(
84 float64_t * pDst,
85 uint32_t blockSize)
86 {
87 float64_t k = 2. / ((float64_t) blockSize);
88 float64_t w;
89
90 for(uint32_t i=0;i<blockSize;i++)
91 {
92 w = PI_F64 * (i * k);
93 w =
94 (1.0 -
95 1.985844164102 * cos (w) +
96 1.791176438506 * cos (2. * w) -
97 1.282075284005 * cos (3. * w) +
98 0.667777530266 * cos (4. * w) -
99 0.240160796576 * cos (5. * w) +
100 0.056656381764 * cos (6. * w) -
101 0.008134974479 * cos (7. * w) +
102 0.000624544650 * cos (8. * w) -
103 0.000019808998 * cos (9. * w) +
104 0.000000132974 * cos (10. * w));
105 pDst[i] = w;
106 }
107 }
108
109 /**
110 @} end of WindowFlat group
111 */
112
113