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LED 一般是恒流操作的，如何改变 LED 的亮度呢？答案就是 PWM 控制。在一定的 频率的方波中，调整高电平和低电平的占空比，即可实现。比如我们用低电平点亮一个 LED 灯，我们假设把一个频率周期分为 10 个时间等份，如果方波中的高低电平占空比是 9：1， 这是就是一个比较暗的亮度，如果方波中高低电平占空比是 10：0，这时 ...

贴片铝电解电容封装库 SMD Aluminum Electrolytic Capacitors VE Features ‧ 3 ~ 16φ, 85℃, 2,000 hours assured ‧ Chip type large capacitance capacitors ‧ Designed for surface mounting on high density PC board. ‧ RoHS Compliance

In this paper, we consider the channel estimation problem in Millimeter wave (mmWave) wireless systems with large antenna arrays. By exploiting the inherent sparse nature of the mmWave channel, we develop a novel rate-adaptive channel estimation (RACE) algorithm, which can adaptively adjust the numb ...

This book examines the technologies underlying the compression and trans- mission of digital video sequences over networking platforms. The incorporated study covers a large spectrum of topics related to compressed video communica- tions. It presents to readers a comprehensive and structured analysi ...

Cellular communications is one of the fastest growing and most challenging telecom- munication applications ever. Today, it represents a large and continuously increasing percentage of all new telephone subscribers around the world. In the long term, cellular digital technology may become the univer ...

The wireless market has experienced a phenomenal growth since the first second- generation (2G) digital cellular networks, based on global system for mobile communications (GSM) technology, were introduced in the early 1990s. Since then, GSM has become the dominant global 2G radio access standard. A ...

In this paper we revisit hybrid analog-digital precoding systems with emphasis on their modelling and radio-frequency (RF) losses, to realistically evaluate their benefits in 5G system implementations. For this, we decompose the analog beamforming networks (ABFN) as a bank of commonly used RF compon ...

When we started thinking about writing the first edition of this book a few years ago, we had been working together for more than five years on the borderline between propagation and signal processing. Therefore, it is not surprising that this book deals with propagation models and design tools for ...

When we started thinking about writing this book, we had been working together for more than five years on the borderline between propagation and signal processing.Therefore, it is not surprising that this book deals with propagation models and design tools for MIMO wirelesscommunications.Yet, thisb ...

Mobile wireless communications are in constant evolution due to the continu- ously increasing requirements and expectations of both users and operators. Mass multimedia* services have been for a long time expected to generate a large amount of data traffic in future wireless networks [1]. Mass multi ...