FCC E8B - 信号处理与发射

#E8B01🔗

What is the modulation index of an FM signal?

FM 信号的调制指数是多少？

The ratio of frequency deviation to modulating signal frequency

频率偏差与调制信号频率的比值

✓ 正确答案

The ratio of modulating signal amplitude to frequency deviation

调制信号幅度与频率偏差之比

The modulating signal frequency divided by the bandwidth of the transmitted signal

调制信号频率除以发射信号的带宽

The bandwidth of the transmitted signal divided by the modulating signal frequency

发射信号的带宽除以调制信号频率

#E8B02🔗

How does the modulation index of a phase-modulated emission vary with RF carrier frequency?

相位调制发射的调制指数如何随射频载波频率变化？

It increases as the RF carrier frequency increases

随着射频载波频率的增加而增加

It decreases as the RF carrier frequency increases

随着射频载波频率的增加而减小

It varies with the square root of the RF carrier frequency

它随射频载波频率的平方根而变化

It does not depend on the RF carrier frequency

它不依赖于射频载波频率

✓ 正确答案

#E8B03🔗

What is the modulation index of an FM phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency if the highest modulating frequency is 1000 Hz?

如果最高调制频率为 1000 Hz，则载波频率两侧最大频率偏差为 3000 Hz 的 FM 电话信号的调制指数是多少？

✓ 正确答案

0.3

0.6

#E8B04🔗

What is the modulation index of an FM phone signal having a maximum carrier deviation of plus or minus 6 kHz if the highest modulating frequency is 2 kHz?

如果最高调制频率为 2 kHz，最大载波偏差为正负 6 kHz 的 FM 电话信号的调制指数是多少？

0.3

✓ 正确答案

0.6

#E8B05🔗

What is the deviation ratio of an FM phone signal having a maximum frequency swing of plus or minus 5 kHz if the highest modulation frequency is 3 kHz?

如果最高调制频率为 3 kHz，最大频率摆幅为正负 5 kHz 的 FM 电话信号的偏差比是多少？

0.167

0.6

1 . 67

1. 67

✓ 正确答案

#E8B06🔗

What is the deviation ratio of an FM phone signal having a maximum frequency swing of plus or minus 7.5 kHz if the highest modulation frequency is 3.5 kHz?

如果最高调制频率为 3.5 kHz，最大频率摆幅为正负 7.5 kHz 的 FM 电话信号的偏差比是多少？

2 . 14

2. 14

✓ 正确答案

0.214

0.47

#E8B07🔗

Orthogonal frequency-division multiplexing (OFDM) is a technique used for which types of amateur communication?

正交频分复用 (OFDM) 是一种用于哪些类型的业余通信的技术？

Digital modes

数字模式

✓ 正确答案

Extremely low-power contacts

极低功耗触点

EME

欧洲及中东地区

OFDM signals are not allowed on amateur bands

业余频段不允许使用 OFDM 信号

#E8B08🔗

What describes orthogonal frequency-division multiplexing (OFDM)?

什么是正交频分复用 (OFDM)？

A frequency modulation technique that uses non-harmonically related frequencies

使用非谐波相关频率的频率调制技术

A bandwidth compression technique using Fourier transforms

使用傅立叶变换的带宽压缩技术

A digital mode for narrow-band, slow-speed transmissions

用于窄带、低速传输的数字模式

A digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference

一种数字调制技术，使用选定频率的子载波来避免码间干扰

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#E8B09🔗

What is deviation ratio?

什么是偏差比？

The ratio of the audio modulating frequency to the center carrier frequency

音频调制频率与中心载波频率的比值

The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency

最大载波频率偏差与最高音频调制频率的比值

✓ 正确答案

The ratio of the carrier center frequency to the audio modulating frequency

载波中心频率与音频调制频率的比值

The ratio of the highest audio modulating frequency to the average audio modulating frequency

最高音频调制频率与平均音频调制频率的比值

#E8B10🔗

What is frequency division multiplexing (FDM)?

什么是频分复用 (FDM)？

The transmitted signal jumps from band to band at a predetermined rate

发射信号以预定速率从一个频段跳到另一个频段

Dividing the transmitted signal into separate frequency bands that each carry a different data stream

将传输的信号划分为单独的频段，每个频段承载不同的数据流

✓ 正确答案

The transmitted signal is divided into packets of information

传输的信号被分成信息包

Two or more information streams are merged into a digital combiner, which then pulse position modulates the transmitter

两个或多个信息流被合并到数字组合器中，然后数字组合器对发射器进行脉冲位置调制

#E8B11🔗

What is digital time division multiplexing?

什么是数字时分复用？

Two or more data streams are assigned to discrete sub-carriers on an FM transmitter

两个或多个数据流被分配给 FM 发射机上的离散子载波

Two or more signals are arranged to share discrete time slots of a data transmission

两个或多个信号被布置为共享数据传输的离散时隙

✓ 正确答案

Two or more data streams share the same channel by transmitting time of transmission as the sub-carrier

两个或多个数据流以传输时间为子载波共享同一信道

Two or more signals are quadrature modulated to increase bandwidth efficiency

对两个或多个信号进行正交调制以提高带宽效率

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FCC E8B - 信号处理与发射

小节 E8B：信号处理与发射