入门指南：无线电系统工程与SystemVue仿真实践

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《Radio Systems Engineering：A Tutorial Approach》是一本于2015年由Springer出版社发行的详尽介绍无线通信系统工程的教程书籍。作者Héctor J. De Los Santos、Christian Sturm和Juan Pontes共同编撰，旨在通过实践案例和深入浅出的方式，引导读者理解和掌握无线通信系统的各个方面。本书分为九个主要章节，每个章节都围绕着关键的主题展开： 1. **Introduction to Radio Systems**：这一章首先介绍了无线通信系统的概述，包括基本概念和技术背景，让读者对整个领域有一个全面的认识。 2. **Modulation and Detection**：这部分着重讲解调制技术，如幅度调制、频率调制和相位调制等，以及信号检测原理，这是无线传输中至关重要的内容，因为它们决定了数据的编码和解码过程。 3. **Typical System Performance Parameters**：这里详细讨论了无线通信系统的关键性能指标，如信噪比（SNR）、带宽效率、吞吐量等，帮助读者理解如何评估系统的性能。 4. **Radio Channel Fundamentals and Antennas**：这一节深入研究无线信道特性，包括多径衰落、阴影衰落、频率选择性衰落等，以及天线设计的基本原理，这些知识对于优化信号传输至关重要。 5. **Noise, Nonlinearity, and Time Variance**：噪声分析、非线性效应以及时间变异性是无线系统中的重要因素，通过这一章的学习，读者将了解如何处理这些影响信号质量的因素。 6. **Sensitivity and Dynamic Range**：探讨接收机的灵敏度和动态范围，这两个参数直接影响到系统的接收能力，尤其是在低信号强度或信号波动的情况下。 7. **Transceiver Architectures**：章节详细介绍了收发器的设计，包括前端处理、信号处理链路和后端接口等，帮助读者理解现代无线设备内部的工作原理。 8. **Case Studies**：书中包含一系列实际案例研究，通过分析和解决实际问题，读者能够将理论知识应用到实际场景中，提升问题解决能力。 9. **Tutorials**：最后的教程部分提供了实用的工具和方法，比如SystemVue的仿真实验，这是一个强大的仿真平台，用于设计、分析和优化无线通信系统，有助于读者在实践中深化理解。《Radio Systems Engineering：A Tutorial Approach》不仅涵盖了无线通信的基础知识，而且通过丰富的案例和实践环节，使读者能够系统地学习和掌握无线通信系统的工程设计和优化策略。对于想要进入或进一步了解无线电工程领域的学生和专业人士来说，这是一本不可或缺的参考书。

1 Introduction to Radio Systems2

desired information to be transmitted, m( t), in its original form, is referred to as the

baseband signal. On the other hand, the continuous high-frequency wave which

carries the baseband signal is referred to as the carrier. The modulation of the car-

rier is effected when the amplitude, the frequency, or the phase of the carrier is made

to vary in a manner dictated by the baseband signal.

The general equation for a continuous single-frequency time function is given

by,

(1.2)

which may be represented as the function of time or phase v( t) as depicted in

Fig. 1.2.

The parameters in (1.2) embody the following. The factor A quantifies the peak

amplitude of v( t), the parameter

is called the radial frequency of the time func-

tion described by (1.2), and the time, T, shown in Fig. 1.2a, is called the period of

the cosine function; it is the time required to change the phase of the time function

radians. Differentiation of (1.2) with respect to time yields the fundamental

relationship,

(1.3)

where,

ϕω ϕ

. From Fig. 1.2 and (1.2) it is seen that a time change of T

changes the phase by

, i.e.,

vt At

() cos( )cos ()=+=

[]

ϕϕ

v(t)

-A

v(ω

-A

2π

Fig. 1.2 Depiction of carrier signal. a As function of time. b As function of phase

Tx Antenna

Rx Antenna

(EM Wave)

DESTINATION

WIRELESS LINK

SOURCE

Fig. 1.1 Depiction of the wireless communications problem. Tx is transmitter; EM is electro-

magnetic; Rx is receiver; Source is the place of transmission; Destination is the place of reception

1 Introduction to Radio Systems4

The source of the information in Fig. 1.3 (block 1), may be a microphone, a

video camera, a temperature sensor, an accelerometer, a seismic sensor, a fluid level

sensor or any other device ( transducer) that transforms the desired information into

an electrical signal.

The electrical (baseband) signal, in turn, is amplified (block 2) and usually

passed through a lowpass filter to limit its bandwidth. The carrier frequency, or a

sub-multiple of it, is generated by an RF oscillator (block 3), which is then multi-

plied and amplified (block 4) to establish the desired frequency. Due to the need

for operation at the precise assigned frequency, the oscillator stability is typically

controlled by a highly stable resonator, such as a quartz crystal.

One or more amplifier stages may be employed to increase the power level of the

signal from that produced by the oscillator to that needed for input to the modulator

(block 5). A variety of power amplification topologies may be used for obtaining

high efficiency, for example, class C [2].

The modulator takes in two inputs, namely, the information-bearing (baseband)

signal and the carrier frequency, and produces the modulated output carrier. If a

higher power level than the one produced by the modulator is desired, additional

amplification (block 6) may be added so the desired power level to be transmitted

by the antenna (block 7) is reached.

On the other hand, the transmitted information is captured by a receiver,

Fig. 1.3b. The receiving antenna (block 8) utilized may be omnidirectional for gen-

eral service, or highly directional for point-to-point communication. The received

wave induces a small voltage in the receiving antenna, with amplitudes ranging

from tens of millivolt to less than a microvolt, depending on a wide variety of

conditions, in particular, the nature of the intervening transmitter-receiver space

or channel. Notice that, en-route to the receiver, the transmitted signal picks up

noise from the environment; this refers to random signals which alter the amplitude,

phase, or frequency of the transmitted carrier. The received signal delivered by the

antenna is amplified by a low noise amplifier (LNA) (block 9) to increase the signal

power to a level appropriate for input to a mixer. The LNA also provides isolation

between the local oscillator (LO) (block 10) and the antenna, as well as increasing

the received signal amplitude to overcome the noise that is inevitably introduced in

the mixer (block 11). The mixer is a nonlinear circuit which produces multiples of

the sum and difference of the RF and local oscillator (LO) signal frequencies, thus

frequency-translating the received carrier signal, f

, to the intermediate frequency,

, where demodulation is to be effected. In the receiver architecture shown, the LO

is tuned to produce a frequency that differs from the incoming signal frequency f

by the intermediate frequency f

; in other words, f

can be equal to either f

+ f

or f

− f

. The IF amplifier (block 12) increases the signal amplitude to a level ap-

propriate for detection, and provides most of the frequency selectivity necessary

to “pass” the desired signal and reject the undesired signals that are found in the

mixer’s output spectrum. The detector (block 13) extracts the original message from

the modulated IF input. The extracted signal is amplified (block 14) to an amplitude

that is appropriate for driving a loudspeaker, a television tube, or other output de-

vice. The output transducer (15) converts the signal information back to its original

form, e.g., a sound wave, a picture, etc.

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