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 @return none
59
60 @par Parameters of the window
61
62 | Parameter | Value |
63 | ------------------------------------: | -----------------: |
64 | Peak sidelobe level | 90.2 dB |
65 | Normalized equivalent noise bandwidth | 3.8832 bins |
66 | 3 dB bandwidth | 3.8320 bins |
67 | Flatness | -0.0039 dB |
68 | Recommended overlap | 76.0 % |
69
70 Included in CMSIS-DSP with authorization from professor
71 Gerhard Heinzel.
72
73 @par Original article:
74 Spectrum and spectral density estimation by the Discrete Fourier
75 transform (DFT), including a comprehensive list of window
76 functions and some new
77 flat-top windows.
78
79 @par Authors:
80 G. Heinzel, A. Rudiger and R. Schilling,
81 Max-Planck-Institut fur Gravitationsphysik
82 (Albert-Einstein-Institut)
83 Teilinstitut Hannover
84 */
85
86
87
arm_hft90d_f32(float32_t * pDst,uint32_t blockSize)88 void arm_hft90d_f32(
89 float32_t * pDst,
90 uint32_t blockSize)
91 {
92 float32_t k = 2.0f / ((float32_t) blockSize);
93 float32_t w;
94
95 for(uint32_t i=0;i<blockSize;i++)
96 {
97 w = PI * (i * k);
98 w =
99 1.0f -
100 1.942604f * cosf (w) +
101 1.340318f * cosf (2.f * w) -
102 0.440811f * cosf (3.f * w) + 0.043097f * cosf (4.f * w);
103
104 pDst[i] = w;
105 }
106 }
107
108 /**
109 @} end of WindowFlat group
110 */
111
112