1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_hft144d_f32.c
4 * Description: Floating-point (f32) Hft144d 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 WindowHFT144D Hft144d window function (144.1 dB)
46
47 */
48
49 /**
50 @ingroup WindowHFT144D
51 */
52
53 /**
54 @brief Hft144d 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
58 @par Parameters of the window
59
60 | Parameter | Value |
61 | ------------------------------------: | -----------------: |
62 | Peak sidelobe level | 144.1 dB |
63 | Normalized equivalent noise bandwidth | 4.5386 bins |
64 | 3 dB bandwidth | 4.4697 bins |
65 | Flatness | 0.0021 dB |
66 | Recommended overlap | 79.9 % |
67
68 Included in CMSIS-DSP with authorization from professor
69 Gerhard Heinzel.
70
71 @par Original article:
72 Spectrum and spectral density estimation by the Discrete Fourier
73 transform (DFT), including a comprehensive list of window
74 functions and some new
75 flat-top windows.
76
77 @par Authors:
78 G. Heinzel, A. Rudiger and R. Schilling,
79 Max-Planck-Institut fur Gravitationsphysik
80 (Albert-Einstein-Institut)
81 Teilinstitut Hannover
82 */
83
84
85
arm_hft144d_f32(float32_t * pDst,uint32_t blockSize)86 ARM_DSP_ATTRIBUTE void arm_hft144d_f32(
87 float32_t * pDst,
88 uint32_t blockSize)
89 {
90 float32_t k = 2.0f / ((float32_t) blockSize);
91 float32_t w;
92
93 for(uint32_t i=0;i<blockSize;i++)
94 {
95 w = PI * (i * k);
96 w =
97 (1.0f -
98 1.96760033f * cosf (w) +
99 1.57983607f * cosf (2.f * w) -
100 0.81123644f * cosf (3.f * w) +
101 0.22583558f * cosf (4.f * w) -
102 0.02773848f * cosf (5.f * w) + 0.00090360f * cosf (6.f * w));
103
104 pDst[i] = w;
105 }
106 }
107
108 /**
109 @} end of WindowFlat group
110 */
111
112
