1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_hft90d_f64.c
4 * Description: Floating-point (f64) 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 @defgroup WindowFlat Flat-top window functions
41
42 Use those windows when you need to estimate the
43 amplitude of a tone.
44
45 If just just need to detect a tone or estimate the
46 noise, you can use the regular windows.
47
48 */
49
50
51 /**
52 @addtogroup WindowFlat
53 @{
54 */
55
56
57 /**
58 @ingroup WindowHFT90D
59 */
60
61 /**
62 @brief Hft90d window generating function (f64).
63 @param[out] pDst points to the output generated window
64 @param[in] blockSize number of samples in the window
65
66 @par Parameters of the window
67
68 | Parameter | Value |
69 | ------------------------------------: | -----------------: |
70 | Peak sidelobe level | 90.2 dB |
71 | Normalized equivalent noise bandwidth | 3.8832 bins |
72 | 3 dB bandwidth | 3.8320 bins |
73 | Flatness | -0.0039 dB |
74 | Recommended overlap | 76.0 % |
75
76 Included in CMSIS-DSP with authorization from professor
77 Gerhard Heinzel.
78
79 @par Original article:
80 Spectrum and spectral density estimation by the Discrete Fourier
81 transform (DFT), including a comprehensive list of window
82 functions and some new
83 flat-top windows.
84
85 @par Authors:
86 G. Heinzel, A. Rudiger and R. Schilling,
87 Max-Planck-Institut fur Gravitationsphysik
88 (Albert-Einstein-Institut)
89 Teilinstitut Hannover
90 */
91
92
93
arm_hft90d_f64(float64_t * pDst,uint32_t blockSize)94 ARM_DSP_ATTRIBUTE void arm_hft90d_f64(
95 float64_t * pDst,
96 uint32_t blockSize)
97 {
98 float64_t k = 2. / ((float64_t) blockSize);
99 float64_t w;
100
101 for(uint32_t i=0;i<blockSize;i++)
102 {
103 w = PI_F64 * (i * k);
104 w =
105 1.0 -
106 1.942604 * cos (w) +
107 1.340318 * cos (2 * w) -
108 0.440811 * cos (3 * w) + 0.043097 * cos (4 * w);
109
110 pDst[i] = w;
111 }
112 }
113
114 /**
115 @} end of WindowFlat group
116 */
117
118
