英语翻译当今社会已经步入信息时代,在各种信息技术中,信息的传输及通信起着支撑作用,人们对通信的要求也越来越高.如何建立更稳定更高效的调制方式是我们需要不断研究和改进的,也是

英语翻译当今社会已经步入信息时代,在各种信息技术中,信息的传输及通信起着支撑作用,人们对通信的要求也越来越高.如何建立更稳定更高效的调制方式是我们需要不断研究和改进的,也是
英语翻译
当今社会已经步入信息时代,在各种信息技术中,信息的传输及通信起着支撑作用,人们对通信的要求也越来越高.如何建立更稳定更高效的调制方式是我们需要不断研究和改进的,也是我们追求的主要目标.
四相相移键控(QPSK)方式在数字调制技术中已占有越来越重要的地位,该调制方式广泛应用于卫星通信、电缆调制解调、视频会议系统、蜂窝电话和其他数字通信等领域.它具有较高的频谱利用率、较强的抗干扰性、很低的比特错误率,在电路上实现也较为简单,对其进行模拟可以不限环境使用这种调制方式,从而可以节省成本费用,进而对其性能进行评估,有利于进一步研究和应用QPSK通信系统.
四相相移调制是利用载波的四种不同相位差来表征输入的数字信息,是四进制移相键控.QPSK是M=4时的调相技术,它规定了四种载波相位,分别为45°,135°,225°,275°,调制器输入的数据是二进制数字序列,为了能和四进制的载波相位配合起来,则需要把二进制数据变换为四进制数据,这就是说需要把二进制数字序列中每两个比特分成一组,共有四种组合,即00,01,10,11,其中每一组称为双比特码元.每一个双比特码元是由两位二进制信息比特组成,它们分别代表四进制四个符号中的一个符号.QPSK中每次调制可传输2个信息比特,这些信息比特是通过载波的四种相位来传递的.解调器根据星座图及接收到的载波信号的相位来判断发送端发送的信息比特.
在调制部分,将输入的串行二进制信息序列经串－并变换,变成m=log2M个并行数据流,每一路的数据率是R/m,R是串行输入码的数据率.I/Q信号发生器将每一个m比特的字节转换成一对（pn,qn）数字,分成两路速率减半的序列,电平发生器分别产生双极性二电平信号I(t)和Q(t),然后对coswct和sinwct进行调制,相加后即得到QPSK信号.
在解调部分,则对QPSK信号的分离,经过低通滤波,抽样判决、将并行信号转换成串行信号的任务,拟将QPSK信号恢复成二进制信息,实现接收端与发送端信息的一致性

英语翻译当今社会已经步入信息时代,在各种信息技术中,信息的传输及通信起着支撑作用,人们对通信的要求也越来越高.如何建立更稳定更高效的调制方式是我们需要不断研究和改进的,也是
Today's society has entered the information age,in a variety of information technology,information transmission and communication plays a supporting role,people demand more and more communication.How to create a more stable and more efficient modulation that we need to continue to study and improve,and it is our main objectives pursued.
Quadrature phase shift keying (QPSK) digital modulation methods have been in possession of more and more important position,the modulation is widely used in satellite communication,cable modem,video conferencing systems,cellular phones and other digital communications and other fields .It has high spectrum efficiency,a strong anti-interference,low bit error rate,the circuit is relatively simple to achieve its simulation environment can be limited to use of this modulation,which can save costs and then evaluate its performance,is conducive to further research and application of QPSK communication system.
Quadrature phase shift carrier modulation is used to represent the four different phase inputs of digital information,is quaternary phase shift keying.Is M = 4 QPSK modulation when the technology,it provides four carrier phase,respectively,45 °,135 °,225 °,275 °,the modulator input data is a binary number sequences,and four hexadecimal order carrier phase together,you need to make binary data is transformed into four binary data,which means that the need to sequence each of the two binary digits into a set of bits,a total of four combinations,namely,00,01,10,11,each of which a group called the two-bit symbol.Two-bit code for each element is composed by two binary bits of information,they represent the four symbols in the quaternary symbol.QPSK modulation can be transmitted each time two bits of information,the information bits through the carrier to pass the four phases.Demodulator and the received constellation phase of the carrier signal to determine the sender to send bits of information.
In the modulation section,the input sequence by the serial string of binary information - and transform into m = log2M parallel data streams,each path data rate is R / m,R is the serial data rate of input code.I / Q signal generator that each of the m-bit bytes into one pair (pn,qn) figures,is divided into two half rate of the sequence,the level generator produces bipolar II were level signal I (t) and Q (t),then coswct and sinwct modulated QPSK signal obtained after adding.
In the demodulation part,the separation of the QPSK signal,after low-pass filter,sample sentence,the parallel signals into serial signal task,intends to resume QPSK signal into a binary information receiver and transmitter to achieve the consistency of information