CN103001606A - digital filter - Google Patents

Abstract

Translated fromChinese

本发明公开了一种数字滤波器，属于数字信号处理领域。该数字滤波器包括滤波程序运行模块、滤波器类型选择模块和截止频率设置模块，滤波器类型选择模块和截止频率设置模块分别与滤波程序运行模块连接。该装置结构简单、使用方便、滤波效果好。

The invention discloses a digital filter, which belongs to the field of digital signal processing. The digital filter includes a filter program running module, a filter type selection module and a cutoff frequency setting module, and the filter type selection module and the cutoff frequency setting module are respectively connected with the filter program running module. The device has the advantages of simple structure, convenient use and good filtering effect.

Description

Translated fromChinese

数字滤波器digital filter

技术领域technical field

本发明涉及一种数字滤波器，属于数字信号处理领域。The invention relates to a digital filter and belongs to the field of digital signal processing.

背景技术Background technique

目前，在数字信号处理领域，对于有用信号与噪声频带分离的情况，人们一般采用经典滤波，即FIR数字滤波器或者IIR数字滤波器，而这两种滤波器的幅频响应都只是逼近理想滤波器的幅频响应。之所以要用FIR或者IIR滤波器来逼近理想滤波器，是因为理想滤波器的冲击响应是无限长的，在物理上不能实现。实际应用当中的滤波器也都是基于硬件实现的。At present, in the field of digital signal processing, for the separation of useful signal and noise frequency bands, people generally use classical filtering, that is, FIR digital filter or IIR digital filter, and the amplitude-frequency response of these two filters is only close to the ideal filter. frequency response of the device. The reason why the FIR or IIR filter is used to approximate the ideal filter is because the impulse response of the ideal filter is infinitely long, which cannot be realized physically. The filters in practical applications are also implemented based on hardware.

 发明内容Contents of the invention

本发明提出了一种数字滤波器，使用简单方便，滤波效果好。The invention provides a digital filter, which is simple and convenient to use and has good filtering effect.

本发明为解决其技术问题采用如下技术方案：The present invention adopts following technical scheme for solving its technical problem:

一种数字滤波器，包括滤波程序运行模块、滤波器类型选择模块和截止频率设置模块，滤波器类型选择模块和截止频率设置模块分别与滤波程序运行模块连接。A digital filter includes a filter program running module, a filter type selection module and a cutoff frequency setting module, and the filter type selection module and the cutoff frequency setting module are respectively connected with the filter program running module.

本发明的有益效果如下：The beneficial effects of the present invention are as follows:

1、结构简单，FIR滤波器和IIR滤波器通常需要知道通带截止频率、阻带截止频率、通带衰减、阻带衰减等参数，而本装置只需要知道截止频率。1. The structure is simple. FIR filters and IIR filters usually need to know the passband cutoff frequency, stopband cutoff frequency, passband attenuation, stopband attenuation and other parameters, but this device only needs to know the cutoff frequency.

2、滤波效果好，通带内的信号无损失的通过，阻带内的信号零通过。2. The filtering effect is good, the signal in the passband passes through without loss, and the signal in the stopband passes through zero.

3、使用灵活方便，不用针对不同的待处理信号修改程序，只需要通过滤波类型选择模块和截止频率设置模块进行设置就可以了。3. It is flexible and convenient to use. It is not necessary to modify the program for different signals to be processed. It only needs to be set through the filter type selection module and the cutoff frequency setting module.

附图说明Description of drawings

图1数字滤波器结构框图。Fig. 1 block diagram of digital filter structure.

图2滤波程序流程图。Figure 2 Flowchart of the filtering program.

具体实施方式Detailed ways

下面结合附图对本发明创造做进一步详细说明。The invention will be described in further detail below in conjunction with the accompanying drawings.

图1所示为数字滤波器的结构框图，该装置包括滤波程序运行模块、滤波器类型选择模块和截止频率设置模块，滤波器类型选择模块和截止频率设置模块分别与滤波程序运行模块连接。滤波器类型选择模块由分别代表四种滤波器类型（低通、高通、带通、带阻）的按键组成；截止频率设置模块由数字键盘组成。滤波器类型和截止频率设置好后，数字滤波器将按照设置对输入信号进行滤波。Figure 1 shows a block diagram of a digital filter. The device includes a filter program running module, a filter type selection module and a cutoff frequency setting module. The filter type selection module and the cutoff frequency setting module are respectively connected to the filter program running module. The filter type selection module is composed of keys representing four filter types (low pass, high pass, band pass, and band stop); the cutoff frequency setting module is composed of a numeric keyboard. After the filter type and cutoff frequency are set, the digital filter will filter the input signal according to the settings.

图2为图1框图中滤波程序运行模块所运行程序的流程图，如果待处理信号是模拟信号，可以对其进行采样，然后进行处理。Fig. 2 is a flow chart of the program run by the filtering program running module in the block diagram of Fig. 1. If the signal to be processed is an analog signal, it can be sampled and then processed.

假设待处理的输入信号为x(n)，先对其进行傅里叶变换得到x(n)的频域信号                                                。如果滤波器类型模块选择的是低通，要进行低通滤波，且低通滤波的截止频率为

，则通带设置模块输入的是，即希望输入信号x(n)中部分通过，

部分滤除，其中

为待处理信号x(n)的频率。对x(n)的频域信号进行如下处理得到

， Assuming that the input signal to be processed is x(n), first perform Fourier transform on it to obtain the frequency domain signal of x(n) . If the filter type module selects low-pass, low-pass filtering needs to be performed, and the cut-off frequency of low-pass filtering is

, then the input of the passband setting module is , that is, it is hoped that the input signal x(n) in partially passed,

partially filtered out, where

is the frequency of the signal x(n) to be processed. frequency domain signal for x(n) Do the following to get

,

               （1） (1)

式中：

指x(n)的归一化角频率，

指与对应的归一化角频率，

为对x(n)进行滤波处理后的频域信号。In the formula:

refers to the normalized angular frequency of x(n),

point to The corresponding normalized angular frequency,

is the frequency domain signal after filtering x(n).

令

为采样频率，则

和

之间满足以下关系      make

is the sampling frequency, then

and

satisfy the following relationship between

                              （2） (2)

同理，对于高通、带通和带阻的情况，分别如式（3）、（4）和（5）所示。Similarly, for high-pass, band-pass and band-stop cases, They are shown in formulas (3), (4) and (5) respectively.

                （3） (3)

        （4）

(4)

          （5）

(5)

式中：对于式（4）和

分别是带通滤波器通带的截止角频率，对于式（5）

和

分别是带阻滤波器阻带的截止角频率。 In the formula: for formula (4) and

are the cut-off angular frequencies of the pass band of the band-pass filter, for formula (5)

and

are the cut-off angular frequencies of the stopband of the bandstop filter, respectively.

得到

后，再对其进行傅里叶反变换即得到滤波后的输出信号y(n)。get

After that, inverse Fourier transform is performed on it to obtain the filtered output signal y(n).

Claims (1)

1. a digital filter is characterized in that comprising that filter operation module, filter type selection module and cut-off frequency arrange module, and filter type selection module is connected module and is connected with filter operation module respectively with cut-off frequency.

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