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.
標簽： frequency-domain interpolation performance Design kbit_s speech coder based and of
上傳時間： 2018-04-08
上傳用戶：kilohorse
在包 hugeinteger 中創建功能類 HugeInteger，該類用來存放和操作一個不超過 40 位的大整數。 (1) 定義一個構造函數，用來對大整數進行初始化。參數為一個字符串。 (2) 定義 input 成員函數，實現大整數的重新賦值。參數為一個字符串，無返回 值。 (3) 定義 output 成員函數，將大整數輸出到屏幕上。無參數無返回值。 (4) 定義 add 成員函數，實現兩個大整數的加法。參數為一個 HugeInteger 對 象，無返回值，例如： HugeInteger A = new HugeInteger("12345"); HugeInteger B = new HugeInteger("1234"); A.add(B); 此時，A 為 13579，B 為 1234。 (5) 定義 sub 成員函數，實現兩個大整數的減法。參數和返回值同 add 函數。 (6) 定義若干大整數關系運算的成員函數，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，≤）。這些函數的參數為一個 HugeInteger 對象，返回值為一個 布爾類型，表示關系運算的結果，例如： HugeInteger A = new HugeInteger("12345"); HugeInteger B = new HugeInteger("1234"); 那么此時 A.isGreaterThan(B)的結果應當為 True，表示 12345>1234。
上傳時間： 2019-06-01
上傳用戶：idealist
Sub 大小寫修正與符號去除()
上傳時間： 2019-07-09
上傳用戶：tkhahah
1．據估計，地球上的綠色植物通過光合作用每年能結合來自CO2中的碳1500億噸和來自水中 的氫250億噸，并釋放4000億噸氧氣。光合作用的過程一般可用下式表示： CO2 + H2O + 微量元素(P、N等) (蛋白質、碳水化臺物、脂肪等)+O2 SHAPE \* MERGEFORMAT 光能 葉綠素 下列說法不正確的是 A．某些無機物通過光合作用可轉化為有機物 B．碳水化合物就是碳和水組成的化合物
上傳時間： 2019-09-11
上傳用戶：hnjhnjhnj
MATLAB數字通信系統仿真， 1) 通過仿真觀察占空比為50%、75%以及100%的單、雙極性歸零碼波形以及其功率譜，分析不同占空比對仿真結果的影響。 通過仿真產生一隨機消息碼序列，將其分別轉換為AMI碼和HDB3碼，觀察它們的波形及其功率譜密度。
上傳時間： 2020-05-20
上傳用戶：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.
標簽： Radiometer Microwave Systems
上傳時間： 2020-05-23
上傳用戶：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.
標簽： Radiometer Microwave Analysis Systems Design
上傳時間： 2020-05-26
上傳用戶：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.
標簽： Bandwidth-Efficient Modulation Digital
上傳時間： 2020-05-26
上傳用戶：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.
標簽： LTE-Advanced Technology Relay
上傳時間： 2020-05-27
上傳用戶：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.
上傳時間： 2020-05-31
上傳用戶：shancjb
