FCC E8C - 信号处理与发射

#E8C01🔗

What is Quadrature Amplitude Modulation or QAM?

什么是正交幅度调制或 QAM？

A technique for digital data compression used in digital television which removes redundancy in the data by comparing bit amplitudes

数字电视中使用的数字数据压缩技术，通过比较位幅度来消除数据中的冗余

Transmission of data by modulating the amplitude of two carriers of the same frequency but 90 degrees out of phase

通过调制同频但异相 90 度的两个载波的幅度来传输数据

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A method of performing single sideband modulation by shifting the phase of the carrier and modulation components of the signal

一种通过移动载波相位和信号调制分量来执行单边带调制的方法

A technique for analog modulation of television video signals using phase modulation and compression

使用相位调制和压缩对电视视频信号进行模拟调制的技术

#E8C02🔗

What is the definition of symbol rate in a digital transmission?

数字传输中符号率的定义是什么？

The number of control characters in a message packet

消息包中控制字符的数量

The maximum rate at which the forward error correction code can make corrections

前向纠错码可以进行纠错的最大速率

The rate at which the waveform changes to convey information

波形改变以传达信息的速率

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The number of characters carried per second by the station-to-station link

站到站链路每秒承载的字符数

#E8C03🔗

Why should the phase of a PSK signal be changed at the zero crossing of the RF signal?

为什么 PSK 信号的相位要在 RF 信号的过零处改变？

To minimize bandwidth

尽量减少带宽

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To simplify modulation

简化调制

To improve carrier suppression

改善载流子抑制

All these choices are correct

所有这些选项都是正确的

#E8C04🔗

What technique minimizes the bandwidth of a PSK31 signal?

什么技术可以最小化 PSK31 信号的带宽？

Zero-sum character encoding

零和字符编码

Reed-Solomon character encoding

里德-所罗门字符编码

Use of sinusoidal data pulses

使用正弦数据脉冲

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Use of linear data pulses

使用线性数据脉冲

#E8C05🔗

What is the approximate bandwidth of a 13-WPM International Morse Code transmission?

13-WPM 国际摩尔斯电码传输的大约带宽是多少？

13 Hz

13赫兹

26 Hz

26赫兹

52 Hz

52赫兹

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104 Hz

104赫兹

#E8C06🔗

What is the bandwidth of an FT8 signal?

FT8 信号的带宽是多少？

10 Hz

10赫兹

50 Hz

50赫兹

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600 Hz

600赫兹

2.4 kHz

2.4kHz

#E8C07🔗

What is the bandwidth of a 4,800-Hz frequency shift, 9,600-baud ASCII FM transmission?

4,800 Hz 频移、9,600 波特率 ASCII FM 传输的带宽是多少？

15 . 36 kHz

15. 36kHz

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9.6 kHz

9.6kHz

4.8 kHz

4.8kHz

5.76 kHz

5.76kHz

#E8C08🔗

How does ARQ accomplish error correction?

ARQ是如何完成纠错的？

Special binary codes provide automatic correction

特殊的二进制代码提供自动更正

Special polynomial codes provide automatic correction

特殊多项式代码提供自动校正

If errors are detected, redundant data is substituted

如果检测到错误，则替换冗余数据

If errors are detected, a retransmission is requested

如果检测到错误，则请求重传

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#E8C09🔗

Which digital code allows only one bit to change between sequential code values?

哪种数字代码只允许在连续代码值之间更改一位？

Binary Coded Decimal Code

二进制编码的十进制代码

Extended Binary Coded Decimal Interchange Code

扩展二进制编码十进制交换码

Extended ASCII

扩展 ASCII

Gray code

格雷码

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#E8C10🔗

How can data rate be increased without increasing bandwidth?

如何在不增加带宽的情况下提高数据速率？

It is impossible

这是不可能的

Increasing analog-to-digital conversion resolution

提高模数转换分辨率

Using a more efficient digital code

使用更高效的数字代码

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Using forward error correction

使用前向纠错

#E8C11🔗

What is the relationship between symbol rate and baud?

符号率和波特率之间有什么关系？

They are the same

他们是一样的

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Baud is twice the symbol rate

波特率是符号率的两倍

Baud rate is half the symbol rate

波特率是符号率的一半

The relationship depends on the specific code used

关系取决于具体使用的代码

#E8C12🔗

What factors affect the bandwidth of a transmitted CW signal?

哪些因素会影响传输的 CW 信号的带宽？

IF bandwidth and Q

中频带宽和 Q

Modulation index and output power

调制指数和输出功率

Keying speed and shape factor ( rise and fall time )

键控速度和形状系数（上升和下降时间）

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All these choices are correct

所有这些选项都是正确的

#E8C13🔗

What is described by the constellation diagram of a QAM or QPSK signal?

QAM 或 QPSK 信号的星座图描述了什么？

How many carriers may be present at the same time

可以同时有多少个运营商

The possible phase and amplitude states for each symbol

每个符号可能的相位和幅度状态

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Frequency response of the signal stream

信号流的频率响应

The number of bits used for error correction in the protocol

协议中用于纠错的位数

#E8C14🔗

What type of addresses do nodes have in a mesh network?

网状网络中的节点有什么类型的地址？

电子邮件

Trust server

信任服务器

Internet Protocol (IP)

互联网协议 (IP)

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Talk group

谈话小组

#E8C15🔗

What technique do individual nodes use to form a mesh network?

各个节点使用什么技术来形成网状网络？

Forward error correction and Viterbi codes

前向纠错和维特比码

Acting as store-and-forward digipeaters

充当存储转发数字中继器

Discovery and link establishment protocols

发现和链路建立协议

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Custom code plugs for the local trunking systems

用于本地集群系统的定制代码插头

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FCC E8C - 信号处理与发射

小节 E8C：信号处理与发射