# 二次均衡器设计
相关文档： [_数字信号系统_](filters.html)
用Traits.UI和Chaco制作的二次均衡器的设计工具，用户可以任意添加二次滤波器，并且调整其中心频率、增益和Q值，并即时查看组合之后的最终频率响应。
```
# -*- coding: utf-8 -*-
import math
from enthought.traits.api import Float, HasTraits, List, Array, on_trait_change, Instance, Range, Button
from enthought.traits.ui.api import View, TableEditor, Item, Group, HGroup, VGroup, HSplit, ScrubberEditor, EnumEditor
from enthought.traits.ui.table_column import ObjectColumn
from enthought.chaco.api import Plot, AbstractPlotData, ArrayPlotData, VPlotContainer
from enthought.chaco.tools.api import PanTool, ZoomTool
from enthought.enable.api import Component, ComponentEditor
from enthought.pyface.api import FileDialog, OK
import pickle
import numpy as np
SAMPLING_RATE = 44100.0 # 取样频率
WORN = 1000 # 频率响应曲线的点数
# 对数圆频率数组
W = np.logspace(np.log10(10/SAMPLING_RATE*np.pi), np.log10(np.pi), WORN)
# 对数频率数组
FREQS = W / 2 / np.pi * SAMPLING_RATE
# 候选频率
EQ_FREQS = [20.0,25.2,31.7,40.0,50.4,63.5,80.0,100.8,
127.0,160.0,201.6,254.0,320.0,403.2,508.0,640.0,
806.3,1015.9,1280.0,1612.7,2031.9,2560.0,3225.4,
4063.7, 5120.0, 6450.8, 8127.5, 10240.0,12901.6,
16255.0,20480.0,]
def scrubber(inc):
'''创建不同增量的ScrubberEditor'''
return ScrubberEditor(
hover_color = 0xFFFFFF,
active_color = 0xA0CD9E,
border_color = 0x808080,
increment = inc
)
def myfreqz(b, a, w):
'''计算滤波器在w个点的频率响应'''
zm1 = np.exp(-1j*w)
h = np.polyval(b[::-1], zm1) / np.polyval(a[::-1], zm1)
return h
def design_equalizer(freq, Q, gain, Fs):
'''设计二次均衡滤波器的系数'''
A = 10**(gain/40.0)
w0 = 2*math.pi*freq/Fs
alpha = math.sin(w0) / 2 / Q
b0 = 1 + alpha * A
b1 = -2*math.cos(w0)
b2 = 1 - alpha * A
a0 = 1 + alpha / A
a1 = -2*math.cos(w0)
a2 = 1 - alpha / A
return [b0/a0,b1/a0,b2/a0], [1.0, a1/a0, a2/a0]
class Equalizer(HasTraits):
freq = Range(10.0, SAMPLING_RATE/2, 1000)
Q = Range(0.1, 10.0, 1.0)
gain = Range(-24.0, 24.0, 0)
a = List(Float, [1.0,0.0,0.0])
b = List(Float, [1.0,0.0,0.0])
h = Array(dtype=np.complex, transient = True)
def __init__(self):
super(Equalizer, self).__init__()
self.design_parameter()
@on_trait_change("freq,Q,gain")
def design_parameter(self):
'''设计系数并计算频率响应'''
try:
self.b, self.a = design_equalizer(self.freq, self.Q, self.gain, SAMPLING_RATE)
except:
self.b, self.a = [1.0,0.0,0.0], [1.0,0.0,0.0]
self.h = myfreqz(self.b, self.a, W)
def export_parameters(self, f):
'''输出滤波器系数为C语言数组'''
tmp = self.b[0], self.b[1], self.b[2], self.a[1], self.a[2], self.freq, self.Q, self.gain
f.write("{%s,%s,%s,%s,%s}, // %s,%s,%s\n" % tmp)
class Equalizers(HasTraits):
eqs = List(Equalizer, [Equalizer()])
h = Array(dtype=np.complex, transient = True)
# Equalizer列表eqs的编辑器定义
table_editor = TableEditor(
columns = [
ObjectColumn(name="freq", width=0.4, style="readonly"),
ObjectColumn(name="Q", width=0.3, style="readonly"),
ObjectColumn(name="gain", width=0.3, style="readonly"),
],
deletable = True,
sortable = True,
auto_size = False,
show_toolbar = True,
edit_on_first_click = False,
orientation = 'vertical',
edit_view = View(
Group(
Item("freq", editor=EnumEditor(values=EQ_FREQS)),
Item("freq", editor=scrubber(1.0)),
Item("Q", editor=scrubber(0.01)),
Item("gain", editor=scrubber(0.1)),
show_border=True,
),
resizable = True
),
row_factory = Equalizer
)
view = View(
Item("eqs", show_label=False, editor=table_editor),
width = 0.25,
height = 0.5,
resizable = True
)
@on_trait_change("eqs.h")
def recalculate_h(self):
'''计算多组均衡器级联时的频率响应'''
try:
tmp = np.array([eq.h for eq in self.eqs if eq.h != None and len(eq.h) == len(W)])
self.h = np.prod(tmp, axis=0)
except:
pass
def export(self, path):
'''将均衡器的系数输出为C语言文件'''
f = file(path, "w")
f.write("double EQ_PARS[][5] = {\n")
f.write("//b0,b1,b2,a0,a1 // frequency, Q, gain\n")
for eq in self.eqs:
eq.export_parameters(f)
f.write("};\n")
f.close()
class EqualizerDesigner(HasTraits):
'''均衡器设计器的主界面'''
equalizers = Instance(Equalizers)
# 保存绘图数据的对象
plot_data = Instance(AbstractPlotData)
# 绘制波形图的容器
container = Instance(Component)
plot_gain = Instance(Component)
plot_phase = Instance(Component)
save_button = Button("Save")
load_button = Button("Load")
export_button = Button("Export")
view = View(
VGroup(
HGroup(
Item("load_button"),
Item("save_button"),
Item("export_button"),
show_labels = False
),
HSplit(
VGroup(
Item("equalizers", style="custom", show_label=False),
show_border=True,
),
Item("container", editor=ComponentEditor(size=(800, 300)), show_label=False),
)
),
resizable = True,
width = 800,
height = 500,
title = u"Equalizer Designer"
)
def _create_plot(self, data, name, type="line"):
p = Plot(self.plot_data)
p.plot(data, name=name, title=name, type=type)
p.tools.append(PanTool(p))
zoom = ZoomTool(component=p, tool_mode="box", always_on=False)
p.overlays.append(zoom)
p.title = name
p.index_scale = "log"
return p
def __init__(self):
super(EqualizerDesigner, self).__init__()
self.plot_data = ArrayPlotData(f=FREQS, gain=[], phase=[])
self.plot_gain = self._create_plot(("f", "gain"), "Gain(dB)")
self.plot_phase = self._create_plot(("f", "phase"), "Phase(degree)")
self.container = VPlotContainer()
self.container.add( self.plot_phase )
self.container.add( self.plot_gain )
self.plot_gain.padding_bottom = 20
self.plot_phase.padding_top = 20
def _equalizers_default(self):
return Equalizers()
@on_trait_change("equalizers.h")
def redraw(self):
gain = 20*np.log10(np.abs(self.equalizers.h))
phase = np.angle(self.equalizers.h, deg=1)
self.plot_data.set_data("gain", gain)
self.plot_data.set_data("phase", phase)
def _save_button_fired(self):
dialog = FileDialog(action="save as", wildcard='EQ files (*.eq)|*.eq')
result = dialog.open()
if result == OK:
f = file(dialog.path, "wb")
pickle.dump( self.equalizers , f)
f.close()
def _load_button_fired(self):
dialog = FileDialog(action="open", wildcard='EQ files (*.eq)|*.eq')
result = dialog.open()
if result == OK:
f = file(dialog.path, "rb")
self.equalizers = pickle.load(f)
f.close()
def _export_button_fired(self):
dialog = FileDialog(action="save as", wildcard='c files (*.c)|*.c')
result = dialog.open()
if result == OK:
self.equalizers.export(dialog.path)
win = EqualizerDesigner()
win.configure_traits()
```
- 用Python做科学计算
- 软件包的安装和介绍
- NumPy-快速处理数据
- SciPy-数值计算库
- matplotlib-绘制精美的图表
- Traits-为Python添加类型定义
- TraitsUI-轻松制作用户界面
- Chaco-交互式图表
- TVTK-三维可视化数据
- Mayavi-更方便的可视化
- Visual-制作3D演示动画
- OpenCV-图像处理和计算机视觉
- Traits使用手册
- 定义Traits
- Trait事件处理
- 设计自己的Trait编辑器
- Visual使用手册
- 场景窗口
- 声音的输入输出
- 数字信号系统
- FFT演示程序
- 频域信号处理
- Ctypes和NumPy
- 自适应滤波器和NLMS模拟
- 单摆和双摆模拟
- 分形与混沌
- 关于本书的编写
- 最近更新
- 源程序集
- 三角波的FFT演示
- 在traitsUI中使用的matplotlib控件
- CSV文件数据图形化工具
- NLMS算法的模拟测试
- 三维标量场观察器
- 频谱泄漏和hann窗
- FFT卷积的速度比较
- 二次均衡器设计
- 单摆摆动周期的计算
- 双摆系统的动画模拟
- 绘制Mandelbrot集合
- 迭代函数系统的分形
- 绘制L-System的分形图