It has been suggested1 that an appropriate figure of merit for a low probability of intercept and detection (LPI/D) Waveform is the quantity “Range x Bandwidth / Joule”. That is, the further the range, the wider the bandwidth and the less amount of energy used to achieve these values, the more covert is the resultant communications system.
標簽： appropriate probability suggested1 intercept
上傳時間： 2017-01-03
上傳用戶：kr770906
A large body of computer-aided techniques has been developed in recent years to assist in the process of modeling, analyzing, and designing communication systems . These computer-aided techniques fall into two categories: formula-based approaches, where the computer is used to evaluate complex formulas, and simulation-based approaches, where the computer is used to simulate the Waveforms or signals that flow through the system. The second approach, which involves “Waveform”-level simulation (and often incorporates analytical techniques), is the subject of this book. Since performance evaluation and trade off studies are the central issues in the analysis and design of communication systems, we will focus on the use of simulation for evaluating the performance of analog and digital communication systems with the emphasis on digitalcommunication systems.
標簽： computer-aided techniques developed assist
上傳時間： 2014-01-01
上傳用戶：541657925
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
The focus of this book is on developing computational algorithms for transmit wave- form design in active sensing applications, such as radar, sonar, communications and medical imaging. Waveforms are designed to achieve certain desired properties, which are divided into three categories corresponding to the three main parts in the book, namely good aperiodic correlations, good periodic correlations and beampattern match- ing.
上傳時間： 2020-06-01
上傳用戶：shancjb
為設計高效率、低損耗的PFC電路,本文基于UCC28019進行電路設計。以UCC28019輸出的PWM波形來控制Boost升壓斬波為核心電路,使電路中的電容交替地充放電、電感交替的儲存和釋放能量,最后實現在輸入AC20V~24V電壓情況下穩定輸出DC38V。測試結果表明,系統實現效率為95%左右,電壓調整率小于1%,電源功率因數0.99。交流輸入電壓為19.0-25.8 V時,輸出直流電壓穩定性較好,電感無明顯嘯叫且紋波小,具有一定的帶負載能力和實用性。In order to design the PFC circuit with high efficiency and low loss,this paper designs the circuit based on UCC28019.The PWM Waveform output by UCC28019 is used to control boost chopper as the core circuit,which alternately charges and discharges capacitors,stores and releases energy by inductors,and finally achieves stable output of DC38 V under the input voltage of AC20 V~24 V.The test results show that the system achieves about 95% efficiency,the voltage adjustment rate is less than 1%,the power factor is 0.99,and the AC input voltage is 19.0-25.8 V.The output DC voltage stability is good,the inductance has no obvious whistle and the ripple is small,so it has certain load capacity and practicability.
上傳時間： 2022-04-03
上傳用戶：
摘要：本系統以ICL8038集成塊為核心器件，制作一種函數信號發生器，制作成本較低。適合學生學習電子技術測量使用。ICL8038是一種具有多種波形輸出的精密振蕩集成電路，只需要個別的外部元件就能產生從0.001Hz~30KlHz的低失真正弦波、三角波、矩形波等脈沖信號。輸出波形的頻率和占空比還可以由電流或電阻控制。另外由于該芯片具有調制信號輸入端，所以可以用來對低頻信號進行頻率調制。關鍵詞：函數信號發生器頻率調制Abstract：The system ICL8038 integrated block as the core device，producing a kind of function signal generator，producing low cost.Suitable for students to learn the use of electronic technology measurement.ICL8038 is a kind of multi-precision oscillator Waveform output integrated circuits，a separate external components only need to be able to generate from the 0.001Hz ~30KHz low-distortion sine wave，triangle wave，square wave pulse signal，etc..Output Waveform of the frequency and duty cycle can also be controlled by a currentor resistance.In addition，as the chip has a modulated signal input terminal，it can be used to low-frequency signal is frequency modulation.
上傳時間： 2022-07-04
上傳用戶：zhanglei193
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