基于查找表的单基FFT原址倒序算法

单基快速Fourier变换(FFT)进行原址运算前需要对输入数据进行倒序,为了提高传统倒序算法的速度,在4个有关单基倒序定理的基础上,提出了基于查找表的单基快速Fourier变换原址倒序算法.该算法通过访问查找表,减少循环次数,简化倒序值的计算过程,从而提高速度.该算法所需查找表的规模不随点数增加而变大.仿真结果表明: 该算法在计算基2倒序时,性能超过了现有算法,在计算非基2倒序时,比传统算法至少快80%, 比现有的查找表算法最多慢15%.     

Performance Analysis of Data Hiding in MPEG-4 AAC Audio

A high capacity data hiding technique was developed for compressed digital audio. As perceptual audio coding has become the accepted technology for storage and transmission of audio signals, compressed audio information hiding enables robust, imperceptible transmission of data within audio signals, thus allowing valuable information to be attached to the content, such as the song title, lyrics, composer’s name, and artist or property rights related data. This paper describes simultaneous low bitrate encodin...     

MEPG-4 AAC 中信息隐藏的研究

为了方便存储和传输,基于心理模型的音频压缩格式得到了广泛的应用.音频信息隐藏技术能够在不降低音质的情况下在音频文件或音频流中传送与音乐相关的内容如歌词、作曲、歌唱家信息或者版权信息等.提出了一种在低码率AAC音频流中隐藏信息的算法,该算法基于人的听觉心理模型的基础上,在量化过程中进行信息的嵌入,并在MPEG-2/4 AAC编码器上进行了实验,结果证明该算法具有较好的鲁棒性,安全性高,并且隐藏容量可以灵活调整.     

Low-Voltage Transconductor with Wide Input Range and Large Tuning Capability

A CMOS triode transconductor was developed with common mode feedback suitable for operating in low-voltage and low-power applications.The design is based on a body-driven input stage with feedback loops to extend both the signal input range and the tuning capability.The effective transconductance of the body-driven triode stage is increased using a partial positive feedback technique which also partially solves the problem introduced by the small transconductance.This design uses the UMC 0.18 μm CMOS process.Simulations show the transconductor operated with 1 V supply voltage has less than 55 dB total harmonic distortions (THD) in the complete tuning range (0 V≤Vcont≤0.43V) for a 1 MHz 0.8 Vp-p differential input.The power consumption is 70 μW for a 0.43 V control voltage.     

MEPG-4 AAC中信息隐藏的研究

为了方便存储和传输，基于心理模型的音频压缩格式得到了广泛的应用，音频信息隐藏技术能够在不降低音质的情况下在音频文件或音频流中传送与音乐相关的内容如歌词、作曲、歌唱家信息或者版权信息等，提出了一种在低码率AAC音频流中隐藏信息的算法，该算法基于人的听觉心里模型的基础上，在量化过程中进行信息的嵌入，并在MPEG-2／4 AAC编码器上进行了实验，结果证明该算法具有较好的鲁棒性，安全性高，并且隐藏容量可以灵活调整。