1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_hft90d_f32.c
4 * Description: Floating-point (f32) Hft90d 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 WindowFlat
42 @{
43 */
44
45 /**
46 @defgroup WindowHFT90D Hft90d window function (90.2 dB)
47
48 */
49
50 /**
51 @ingroup WindowHFT90D
52 */
53
54 /**
55 @brief Hft90d 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 | 90.2 dB |
64 | Normalized equivalent noise bandwidth | 3.8832 bins |
65 | 3 dB bandwidth | 3.8320 bins |
66 | Flatness | -0.0039 dB |
67 | Recommended overlap | 76.0 % |
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_hft90d_f32(float32_t * pDst,uint32_t blockSize)87 ARM_DSP_ATTRIBUTE void arm_hft90d_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 1.942604f * cosf (w) +
100 1.340318f * cosf (2.f * w) -
101 0.440811f * cosf (3.f * w) + 0.043097f * cosf (4.f * w);
102
103 pDst[i] = w;
104 }
105 }
106
107 /**
108 @} end of WindowFlat group
109 */
110
111
