根据PCM／FM信号的特点，提出一种基于离散短时傅里叶变换（discrete short time Fourier transform，DSTFT）的软件化解调方法：首先利用DST-FT计算PCM／FM信号的0、1频点的频谱能量，然后通过比较2个频点频谱能量的大小实现信号的判...根据PCM／FM信号的特点，提出一种基于离散短时傅里叶变换（discrete short time Fourier transform，DSTFT）的软件化解调方法：首先利用DST-FT计算PCM／FM信号的0、1频点的频谱能量，然后通过比较2个频点频谱能量的大小实现信号的判决；详细论述此种解调方法的基本原理和实现过程，提出采用小数形式的频点来提高解调精度；利用C＋＋语言编程实现了该解调方法，并用从实装设备采集的PCM／FM信号对解调软件进行测试。测试结果表明：该方法对PCM／FM信号具有较好的解调性能，且实现原理简洁，运行效率较高，具有一定的工程应用价值。展开更多
针对短波突发FSK信号解调中存在突发检测和同步判决的问题,提出了一种基于谱熵检测和短时傅里叶变换(Discrete short time Fourier transform,DSTFT)判决的突发信号解调方法。根据信号和噪声在频段内功率谱熵分布的不同,利用谱熵可有效...针对短波突发FSK信号解调中存在突发检测和同步判决的问题,提出了一种基于谱熵检测和短时傅里叶变换(Discrete short time Fourier transform,DSTFT)判决的突发信号解调方法。根据信号和噪声在频段内功率谱熵分布的不同,利用谱熵可有效区分信号段和噪声段,为信号解调提供连续有用信息。在FSK解调中提出了具有抗噪声性能的载频附近功率累积量的码元判决方法,同时采用具有抗频偏的载频附近峰值比的码元同步方法。仿真结果表明:基于谱熵的检测方法可有效满足突发信号检测,本文解调方法在低信噪比下具有更低的解调误码率,结合谱熵检测可有效满足突发信号的精确识别和解调。展开更多
提出了一种基于离散短时傅里叶变换的逐码滑动差分四相相移键控（differential quadrature phase-shift keying，DQPSK）信号解调算法：首先利用数字测频完成位同步；再利用离散短时傅里叶变换（discrete short time Fourier transform...提出了一种基于离散短时傅里叶变换的逐码滑动差分四相相移键控（differential quadrature phase-shift keying，DQPSK）信号解调算法：首先利用数字测频完成位同步；再利用离散短时傅里叶变换（discrete short time Fourier transform，DSTFT）后的频域相位信息，完成对信号的差分解调。详细阐述了算法的解调原理和过程，分析了对遥测信号解调的适用情况，给出了对比仿真结果。该算法解调性能良好，运行效率高，便于软件化实时处理。展开更多
As the fractional Fourier transform has attracted a considerable amount of attention in the area of optics and signal processing, the discretization of the fractional Fourier transform becomes vital for the applicatio...As the fractional Fourier transform has attracted a considerable amount of attention in the area of optics and signal processing, the discretization of the fractional Fourier transform becomes vital for the application of the fractional Fourier transform. Since the discretization of the fractional Fourier transform cannot be obtained by directly sampling in time domain and the fractional Fourier domain, the discretization of the fractional Fourier transform has been investigated recently. A summary of discretizations of the fractional Fourier transform developed in the last nearly two decades is presented in this paper. The discretizations include sampling in the fractional Fourier domain, discrete-time fractional Fourier transform, fractional Fourier series, discrete fractional Fourier transform （including 3 main types： linear combination-type; sampling-type; and eigen decomposition-type）, and other discrete fractional signal transform. It is hoped to offer a doorstep for the readers who are interested in the fractional Fourier transform.展开更多
文摘根据PCM／FM信号的特点，提出一种基于离散短时傅里叶变换（discrete short time Fourier transform，DSTFT）的软件化解调方法：首先利用DST-FT计算PCM／FM信号的0、1频点的频谱能量，然后通过比较2个频点频谱能量的大小实现信号的判决；详细论述此种解调方法的基本原理和实现过程，提出采用小数形式的频点来提高解调精度；利用C＋＋语言编程实现了该解调方法，并用从实装设备采集的PCM／FM信号对解调软件进行测试。测试结果表明：该方法对PCM／FM信号具有较好的解调性能，且实现原理简洁，运行效率较高，具有一定的工程应用价值。
文摘针对短波突发FSK信号解调中存在突发检测和同步判决的问题,提出了一种基于谱熵检测和短时傅里叶变换(Discrete short time Fourier transform,DSTFT)判决的突发信号解调方法。根据信号和噪声在频段内功率谱熵分布的不同,利用谱熵可有效区分信号段和噪声段,为信号解调提供连续有用信息。在FSK解调中提出了具有抗噪声性能的载频附近功率累积量的码元判决方法,同时采用具有抗频偏的载频附近峰值比的码元同步方法。仿真结果表明:基于谱熵的检测方法可有效满足突发信号检测,本文解调方法在低信噪比下具有更低的解调误码率,结合谱熵检测可有效满足突发信号的精确识别和解调。
文摘提出了一种基于离散短时傅里叶变换的逐码滑动差分四相相移键控（differential quadrature phase-shift keying，DQPSK）信号解调算法：首先利用数字测频完成位同步；再利用离散短时傅里叶变换（discrete short time Fourier transform，DSTFT）后的频域相位信息，完成对信号的差分解调。详细阐述了算法的解调原理和过程，分析了对遥测信号解调的适用情况，给出了对比仿真结果。该算法解调性能良好，运行效率高，便于软件化实时处理。
基金the National Natural Science Foundation of China (Grant Nos.60232010 and 60572094)the National Natural Science Founda-tion of China for Distinguished Young Scholars (Grant No.60625104)
文摘As the fractional Fourier transform has attracted a considerable amount of attention in the area of optics and signal processing, the discretization of the fractional Fourier transform becomes vital for the application of the fractional Fourier transform. Since the discretization of the fractional Fourier transform cannot be obtained by directly sampling in time domain and the fractional Fourier domain, the discretization of the fractional Fourier transform has been investigated recently. A summary of discretizations of the fractional Fourier transform developed in the last nearly two decades is presented in this paper. The discretizations include sampling in the fractional Fourier domain, discrete-time fractional Fourier transform, fractional Fourier series, discrete fractional Fourier transform （including 3 main types： linear combination-type; sampling-type; and eigen decomposition-type）, and other discrete fractional signal transform. It is hoped to offer a doorstep for the readers who are interested in the fractional Fourier transform.
