1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_nuttall4a_f32.c
4 * Description: Floating-point (f32) Nuttall4a 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 /**
34 @ingroup groupWindow
35 */
36
37
38
39
40 /**
41 @addtogroup WindowNormal
42 @{
43 */
44
45 /**
46 @defgroup WindowNUTTALL4A Nuttall4a window function (82.6 dB)
47
48 */
49
50 /**
51 @ingroup WindowNUTTALL4A
52 */
53
54 /**
55 @brief Nuttall4a window generating function (f32).
56 @param[out] pDst points to the output generated window
57 @param[in] blockSize number of samples in the window
58
59 @par Parameters of the window
60
61 | Parameter | Value |
62 | ------------------------------------: | -----------------: |
63 | Peak sidelobe level | 82.6 dB |
64 | Normalized equivalent noise bandwidth | 2.1253 bins |
65 | 3 dB bandwidth | 2.0123 bins |
66 | Flatness | -0.7321 dB |
67 | Recommended overlap | 68.0 % |
68
69 */
70
71
72
arm_nuttall4a_f32(float32_t * pDst,uint32_t blockSize)73 void arm_nuttall4a_f32(
74 float32_t * pDst,
75 uint32_t blockSize)
76 {
77 float32_t k = 2.0f / ((float32_t) blockSize);
78 float32_t w;
79
80 for(uint32_t i=0;i<blockSize;i++)
81 {
82 w = PI * i * k;
83 w = 0.338946f - 0.481973f * cosf (w) +
84 0.161054f * cosf (2.f * w) - 0.018027f * cosf (3.f * w);
85
86 pDst[i] = w;
87 }
88 }
89
90 /**
91 @} end of WindowNormal group
92 */
93
94
