Python中的频移键控

问题描述

我正在寻找一个数字信号，并使用python将数字0和1调制为模拟信号。我遇到的问题是，波浪移动时，波浪似乎朝错误的方向前进。到目前为止，这是我的代码，我知道它并不漂亮。

import numpy as np
import math

import matplotlib.pyplot as plot

def plotPoint():
    current = 0
    amplitude = 1
    frequency = 2000
    X = []
    Y1 = []
    Y2 = []
    signal= [1,1,0]


    while current < 10000:
        if current < 1000 and signal[0] == 1:
            Y2.append(1)
        elif current < 2000 and current >= 1000 and signal[1] == 1:
            Y2.append(1)
        elif current < 3000 and current >= 2000 and signal[2] == 1:
            Y2.append(1)
        elif current < 4000 and current >= 3000 and signal[3] == 1:
            Y2.append(1)
        elif current < 5000 and current >= 4000 and signal[4] == 1:
            Y2.append(1)
        elif current < 6000 and current >= 5000 and signal[5] == 1:
            Y2.append(1)
        elif current < 7000 and current >= 6000 and signal[6] == 1:
            Y2.append(1)
        elif current < 8000 and current >= 7000 and signal[7] == 1:
            Y2.append(1)
        elif current < 9000 and current >= 8000 and signal[8] == 1:
            Y2.append(1)
        elif current < 10000 and current >= 9000 and signal[9] == 1:
            Y2.append(1)
        else:
            Y2.append(0)
    
    
        
        if Y2[-1] == 1:
            point2 = amplitude*math.sin((2*np.pi/frequency)*current)
        else:
            point2 = amplitude*math.sin((2*np.pi/(frequency/2)*current)
    
        X.append(current)
        Y1.append(point2)
   
    
        current += 1

    plot.plot(X,Y1)
    plot.plot(X,Y2)


    plot.title('Digital Signal')
    plot.xlabel('Time')
    plot.ylabel('Amplitude')
    plot.grid(True,which='both')
    #plot.axhline(y=0,color='k')

    plot.show()


plotPoint()

您可以看到同时显示了数字和模拟信号。我使用2kHz的频率作为载波，您可以在这张图片中看到它的偏移情况

怎么了？我该如何补救？

解决方法

根据每位大叔的建议，这需要对您的代码进行小幅修正：

if Y2[-1] == 1:
    point2 = amplitude*math.sin((2*np.pi/(frequency/2))*current)
else:
    point2 = amplitude*math.sin((2*np.pi/(frequency/4)*current))

这是您要寻找的吗？

,

此代码适用于频率和间隔的任意组合：

amplitude = 1
frequencies = [1200,4000]
X = []
Y1 = []
Y2 = []
signal= [1,1,0]
interval = 1000
phase = 0

for s in signal:
    frequency = frequencies[s]
    for t in range (interval):
        phase += frequency/1000000 * math.pi * 2
        Y2.append(s)
        Y1.append(math.sin(phase) * amplitude)

X = range(len(signal)*interval)
ax,fig = plot.subplots(figsize=(16,2))
plot.plot(X,Y1)
plot.plot(X,Y2)

plot.title('Digital Signal')
plot.xlabel('Time')
plot.ylabel('Amplitude')
plot.grid(True,which='both')