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/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_hft248d_f32.c
* Description: Floating-point (f32) Hft248d window
*
* $Date: 14 December 2022
* $Revision: v1.15.0
*
* Target Processor: Cortex-M and Cortex-A cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2022 ARM Limited or its affiliates. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "arm_compiler_specific.h"
#include "dsp/window_functions.h"
#include "dsp/fast_math_functions.h"
#include <math.h>
/**
@ingroup groupWindow
*/
/**
@addtogroup WindowFlat
@{
*/
/**
@defgroup WindowHFT248D Hft248d window function (248.4 dB)
*/
/**
@ingroup WindowHFT248D
*/
/**
@brief Hft248d window generating function (f32).
@param[out] pDst points to the output generated window
@param[in] blockSize number of samples in the window
@par Parameters of the window
| Parameter | Value |
| ------------------------------------: | -----------------: |
| Peak sidelobe level | 248.4 dB |
| Normalized equivalent noise bandwidth | 5.6512 bins |
| 3 dB bandwidth | 5.5567 bins |
| Flatness | 0.0009 dB |
| Recommended overlap | 84.1 % |
Included in CMSIS-DSP with authorization from professor
Gerhard Heinzel.
@par Original article:
Spectrum and spectral density estimation by the Discrete Fourier
transform (DFT), including a comprehensive list of window
functions and some new
flat-top windows.
@par Authors:
G. Heinzel, A. Rudiger and R. Schilling,
Max-Planck-Institut fur Gravitationsphysik
(Albert-Einstein-Institut)
Teilinstitut Hannover
*/
ARM_DSP_ATTRIBUTE void arm_hft248d_f32(
float32_t * pDst,
uint32_t blockSize)
{
float32_t k = 2.0f / ((float32_t) blockSize);
float32_t w;
for(uint32_t i=0;i<blockSize;i++)
{
w = PI * (i * k);
w =
(1.0f -
1.985844164102f * cosf (w) +
1.791176438506f * cosf (2.f * w) -
1.282075284005f * cosf (3.f * w) +
0.667777530266f * cosf (4.f * w) -
0.240160796576f * cosf (5.f * w) +
0.056656381764f * cosf (6.f * w) -
0.008134974479f * cosf (7.f * w) +
0.000624544650f * cosf (8.f * w) -
0.000019808998f * cosf (9.f * w) +
0.000000132974f * cosf (10.f * w));
pDst[i] = w;
}
}
/**
@} end of WindowFlat group
*/
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