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.
标签： appropriate probability suggested1 intercept
上传时间： 2017-01-03
上传用户：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.
标签： computer-aided techniques developed assist
上传时间： 2013-12-31
上传用户：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.
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
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.
上传时间： 2020-06-01
上传用户：shancjb
为设计高效率、低损耗的PFC电路,本文基于UCC28019进行电路设计。以UCC28019输出的PWM波形来控制Boost升压斩波为核心电路,使电路中的电容交替地充放电、电感交替的储存和释放能量,最后实现在输入AC20V~24V电压情况下稳定输出DC38V。测试结果表明,系统实现效率为95%左右,电压调整率小于1%,电源功率因数0.99。交流输入电压为19.0-25.8 V时,输出直流电压稳定性较好,电感无明显啸叫且纹波小,具有一定的带负载能力和实用性。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.
上传时间： 2022-04-03
上传用户：ddk
摘要：本系统以ICL8038集成块为核心器件，制作一种函数信号发生器，制作成本较低。适合学生学习电子技术测量使用。ICL8038是一种具有多种波形输出的精密振荡集成电路，只需要个别的外部元件就能产生从0.001Hz~30KlHz的低失真正弦波、三角波、矩形波等脉冲信号。输出波形的频率和占空比还可以由电流或电阻控制。另外由于该芯片具有调制信号输入端，所以可以用来对低频信号进行频率调制。关键词：函数信号发生器频率调制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.
上传时间： 2022-07-03
上传用户：zhanglei193
