The 4.0 kbit/s speech codec described in this paper is based on a Frequency Domain Interpolative (FDI) coding technique, which belongs to the class of prototype waveform Interpolation (PWI) coding techniques. The codec also has an integrated voice activity detector (VAD) and a noise reduction capability. The input signal is subjected to LPC analysis and the prediction residual is separated into a slowly evolving waveform (SEW) and a rapidly evolving waveform (REW) components. The SEW magnitude component is quantized using a hierarchical predictive vector quantization approach. The REW magnitude is quantized using a gain and a sub-band based shape. SEW and REW phases are derived at the decoder using a phase model, based on a transmitted measure of voice periodicity. The spectral (LSP) parameters are quantized using a combination of scalar and vector quantizers. The 4.0 kbits/s coder has an algorithmic delay of 60 ms and an estimated floating point complexity of 21.5 MIPS. The performance of this coder has been evaluated using in-house MOS tests under various conditions such as background noise. channel errors, self-tandem. and DTX mode of operation, and has been shown to be statistically equivalent to ITU-T (3.729 8 kbps codec across all conditions tested.
标签： frequency-domain interpolation performance Design kbit_s speech coder based and of
上传时间： 2018-04-08
上传用户：kilohorse
在包 hugeinteger 中创建功能类 HugeInteger，该类用来存放和操作一个不超过 40 位的大整数。 (1) 定义一个构造函数，用来对大整数进行初始化。参数为一个字符串。 (2) 定义 input 成员函数，实现大整数的重新赋值。参数为一个字符串，无返回 值。 (3) 定义 output 成员函数，将大整数输出到屏幕上。无参数无返回值。 (4) 定义 add 成员函数，实现两个大整数的加法。参数为一个 HugeInteger 对 象，无返回值，例如： HugeInteger A = new HugeInteger("12345"); HugeInteger B = new HugeInteger("1234"); A.add(B); 此时，A 为 13579，B 为 1234。 (5) 定义 sub 成员函数，实现两个大整数的减法。参数和返回值同 add 函数。 (6) 定义若干大整数关系运算的成员函数，包括 isEqualTo（等于，=）、 isNotEqualTo（不等于，≠）、isGreaterThan（大于，>）、isLessThan（小 于，<）、isGreaterThanOrEqualTo（大于等于，≥）和 isLessThanOrEqualTo （小于等于，≤）。这些函数的参数为一个 HugeInteger 对象，返回值为一个 布尔类型，表示关系运算的结果，例如： HugeInteger A = new HugeInteger("12345"); HugeInteger B = new HugeInteger("1234"); 那么此时 A.isGreaterThan(B)的结果应当为 True，表示 12345>1234。
上传时间： 2019-06-01
上传用户：idealist
Sub 大小写修正与符号去除()
上传时间： 2019-07-09
上传用户：tkhahah
1．据估计，地球上的绿色植物通过光合作用每年能结合来自CO2中的碳1500亿吨和来自水中 的氢250亿吨，并释放4000亿吨氧气。光合作用的过程一般可用下式表示： CO2 + H2O + 微量元素(P、N等) (蛋白质、碳水化台物、脂肪等)+O2 SHAPE \* MERGEFORMAT 光能 叶绿素 下列说法不正确的是 A．某些无机物通过光合作用可转化为有机物 B．碳水化合物就是碳和水组成的化合物
上传时间： 2019-09-11
上传用户：hnjhnjhnj
MATLAB数字通信系统仿真， 1) 通过仿真观察占空比为50%、75%以及100%的单、双极性归零码波形以及其功率谱，分析不同占空比对仿真结果的影响。 通过仿真产生一随机消息码序列，将其分别转换为AMI码和HDB3码，观察它们的波形及其功率谱密度。
上传时间： 2020-05-20
上传用户：sdf543
Two important microwave remote sensors are the radar and the radiometer. There have been a number of books written on various aspects of radar, but there have been only a few written on microwave radiometers, especially on sub- jects of how to design and build radiometer systems. This book, which is the second edition of a book originally published in 1989, attempts to fill this void.
标签： Radiometer Microwave Systems
上传时间： 2020-05-23
上传用户：shancjb
Two important microwave remote sensors are the radar and the radiometer. There have been a number of books written on various aspects of radar, but there have been only a few written on microwave radiometers, especially on sub- jects of how to design and build radiometer systems. This book, which is the second edition of a book originally published in 1989, attempts to fill this void.
标签： Radiometer Microwave Analysis Systems Design
上传时间： 2020-05-26
上传用户：shancjb
Traditional modulation methods adopted by space agencies for transmit- ting telecommand and telemetry data have incorporated subcarriers as a sim- ple means of separating different data types as well ensuring no overlap between the radio frequency (RF) carrier and the modulated data’s frequency spectra.
标签： Bandwidth-Efficient Modulation Digital
上传时间： 2020-05-26
上传用户：shancjb
LTE-Advanced becomes a truly global standard for 4G cellular communications. Relay, as one of the key technologies of LTE-Advanced, can significantly extend the coverage, and improve the system throughput. LTE-A standards and tech- nologies were described in several recent books where the limited pages for relay feature prevent the detailed explanations of the technology. In this book, we tried to provide an in-depth description of LTE-A relay development. More specifically, significant portions are spent on relay channel modeling and potential technologies during the study item phase of the development, although some of those tech- nologies, such as Type 2 cooperative relay, multi-hop relay, relay with backhaul of carrier aggregation, were not standardized in Release 10 LTE.
标签： LTE-Advanced Technology Relay
上传时间： 2020-05-27
上传用户：shancjb
Before delving into the details of orthogonal frequency division multiplexing (OFDM), relevant background material must be presented first. The purpose of this chapter is to provide the necessary building blocks for the development of OFDM principles. Included in this chapter are reviews of stochastic and random process, discrete-time signals and systems, and the Discrete Fourier Transform (DFT). Tooled with the necessary mathematical foundation, we proceed with an overview of digital communication systems and OFDM communication systems. We conclude the chapter with summaries of the OFDM wireless LAN standards currently in existence and a high-level comparison of single carrier systems versus OFDM.
上传时间： 2020-05-31
上传用户：shancjb
