1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_hft248d_f32.c
4 * Description: Floating-point (f32) 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 @defgroup WindowHFT248D Hft248d window function (248.4 dB)
46
47 */
48
49 /**
50 @ingroup WindowHFT248D
51 */
52
53 /**
54 @brief Hft248d window generating function (f32).
55 @param[out] pDst points to the output generated window
56 @param[in] blockSize number of samples in the window
57 @return none
58
59 @par Parameters of the window
60
61 | Parameter | Value |
62 | ------------------------------------: | -----------------: |
63 | Peak sidelobe level | 248.4 dB |
64 | Normalized equivalent noise bandwidth | 5.6512 bins |
65 | 3 dB bandwidth | 5.5567 bins |
66 | Flatness | 0.0009 dB |
67 | Recommended overlap | 84.1 % |
68
69 Included in CMSIS-DSP with authorization from professor
70 Gerhard Heinzel.
71
72 @par Original article:
73 Spectrum and spectral density estimation by the Discrete Fourier
74 transform (DFT), including a comprehensive list of window
75 functions and some new
76 flat-top windows.
77
78 @par Authors:
79 G. Heinzel, A. Rudiger and R. Schilling,
80 Max-Planck-Institut fur Gravitationsphysik
81 (Albert-Einstein-Institut)
82 Teilinstitut Hannover
83 */
84
85
86
arm_hft248d_f32(float32_t * pDst,uint32_t blockSize)87 void arm_hft248d_f32(
88 float32_t * pDst,
89 uint32_t blockSize)
90 {
91 float32_t k = 2.0f / ((float32_t) blockSize);
92 float32_t w;
93
94 for(uint32_t i=0;i<blockSize;i++)
95 {
96 w = PI * (i * k);
97 w =
98 (1.0f -
99 1.985844164102f * cosf (w) +
100 1.791176438506f * cosf (2.f * w) -
101 1.282075284005f * cosf (3.f * w) +
102 0.667777530266f * cosf (4.f * w) -
103 0.240160796576f * cosf (5.f * w) +
104 0.056656381764f * cosf (6.f * w) -
105 0.008134974479f * cosf (7.f * w) +
106 0.000624544650f * cosf (8.f * w) -
107 0.000019808998f * cosf (9.f * w) +
108 0.000000132974f * cosf (10.f * w));
109 pDst[i] = w;
110 }
111 }
112
113 /**
114 @} end of WindowFlat group
115 */
116
117