1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_welch_f32.c
4 * Description: Floating-point (f32) Welch 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
31 /**
32 @ingroup groupWindow
33 */
34
35
36
37
38 /**
39 @addtogroup WindowNormal
40 @{
41 */
42
43 /**
44 @defgroup WindowWELCH Welch window function (21.3 dB)
45
46 */
47
48 /**
49 @ingroup WindowWELCH
50 */
51
52 /**
53 @brief Welch window generating function (f32).
54 @param[out] pDst points to the output generated window
55 @param[in] blockSize number of samples in the window
56
57 @par Parameters of the window
58
59 | Parameter | Value |
60 | ------------------------------------: | -----------------: |
61 | Peak sidelobe level | 21.3 dB |
62 | Normalized equivalent noise bandwidth | 1.2 bins |
63 | 3 dB bandwidth | 1.1535 bins |
64 | Flatness | -2.2248 dB |
65 | Recommended overlap | 29.3 % |
66
67 */
68
69
70
arm_welch_f32(float32_t * pDst,uint32_t blockSize)71 ARM_DSP_ATTRIBUTE void arm_welch_f32(
72 float32_t * pDst,
73 uint32_t blockSize)
74 {
75 float32_t k = 2.0f / ((float32_t) blockSize);
76 float32_t w;
77
78 for(uint32_t i=0;i<blockSize;i++)
79 {
80 w = i * k - 1.0f;
81 w = 1.0f - w * w;
82 pDst[i] = w;
83 }
84 }
85
86 /**
87 @} end of WindowNormal group
88 */
89
90
