FCC G8C - 信号与发射模式

#G8C02🔗

Which digital mode is used as a low-power beacon for assessing HF propagation?

哪种数字模式用作评估高频传播的低功率信标？

WSPR

✓ 正确答案

MFSK16

PSK31

相移键控31

SSB-SC

单边带-SC

#G8C03🔗

What part of a packet radio frame contains the routing and handling information?

分组无线帧的哪一部分包含路由和处理信息？

Directory

Preamble

序言

Header

标头

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Trailer

预告片

#G8C04🔗

Which of the following describes Baudot code?

以下哪项描述了 Baudot 码？

A 7-bit code with start, stop, and parity bits

带有起始位、停止位和奇偶校验位的 7 位代码

A code using error detection and correction

使用错误检测和纠正的代码

A 5 -bit code with additional start and stop bits

带有附加起始位和停止位的 5 位代码

✓ 正确答案

A code using SELCAL and LISTEN

使用 SELCAL 和 LISTEN 的代码

#G8C05🔗

In an ARQ mode, what is meant by a NAK response to a transmitted packet?

在 ARQ 模式中，对传输的数据包的 NAK 响应意味着什么？

Request retransmission of the packet

请求重传数据包

✓ 正确答案

Packet was received without error

数据包已收到，没有错误

Receiving station connected and ready for transmissions

接收站已连接并准备好传输

Entire file received correctly

整个文件已正确接收

#G8C06🔗

What action results from a failure to exchange information due to excessive transmission attempts when using an ARQ mode?

使用ARQ模式时，由于传输尝试过多而无法交换信息，会导致什么后果？

The checksum overflows

校验和溢出

The connection is dropped

连接已断开

✓ 正确答案

Packets will be routed incorrectly

数据包将被错误路由

Encoding reverts to the default character set

编码恢复为默认字符集

#G8C07🔗

Which of the following narrow-band digital modes can receive signals with very low signal-to-noise ratios?

以下哪种窄带数字模式可以接收信噪比非常低的信号？

MSK144

FT8

✓ 正确答案

AMTOR

MFSK32

#G8C08🔗

Which of the following statements is true about PSK31?

以下关于 PSK31 的哪些说法是正确的？

Upper case letters are sent with more power

大写字母发送时更有力量

Upper case letters use longer Varicode bit sequences and thus slow down transmission

大写字母使用较长的 Varicode 位序列，从而减慢传输速度

✓ 正确答案

Error correction is used to ensure accurate message reception

使用纠错来确保准确的消息接收

Higher power is needed as compared to RTTY for similar error rates

与 RTTY 相比，需要更高的功率才能实现相似的错误率

#G8C09🔗

Which is true of mesh network microwave nodes?

对于网状网络微波节点来说，哪一项是正确的？

Having more nodes increases signal strengths

拥有更多节点可增强信号强度

If one node fails , a packet may still reach its target station via an alternate node

如果一个节点发生故障，数据包仍可能通过备用节点到达其目标站。

✓ 正确答案

Links between two nodes in a network may have different frequencies and bandwidths

网络中两个节点之间的链路可能具有不同的频率和带宽

More nodes reduce overall microwave out of band interference

更多节点减少整体微波带外干扰

#G8C10🔗

How does forward error correction (FEC) allow the receiver to correct data errors?

前向纠错 (FEC) 如何允许接收器纠正数据错误？

By controlling transmitter output power for optimum signal strength

通过控制发射机输出功率以获得最佳信号强度

By using the Varicode character set

通过使用 Varicode 字符集

By transmitting redundant information with the data

通过与数据一起传输冗余信息

✓ 正确答案

By using a parity bit with each character

通过对每个字符使用奇偶校验位

#G8C11🔗

How are the two separate frequencies of a Frequency Shift Keyed (FSK) signal identified?

如何识别频移键控 (FSK) 信号的两个独立频率？

Dot and dash

点和划

On and off

打开和关闭

High and low

高与低

Mark and space

标记和空间

✓ 正确答案

#G8C12🔗

Which type of code is used for sending characters in a PSK31 signal?

哪种类型的代码用于在 PSK31 信号中发送字符？

Varicode

变码

✓ 正确答案

Viterbi

维特比

Volumetric

体积式

Binary

二进制

#G8C13🔗

What is indicated on a waterfall display by one or more vertical lines on either side of a data mode or RTTY signal?

数据模式或 RTTY 信号两侧的一条或多条垂直线在瀑布显示上表示什么？

Long path propagation

长路径传播

Backscatter propagation

反向散射传播

Insufficient modulation

调制不足

Overmodulation

过调制

✓ 正确答案

#G8C14🔗

Which of the following describes a waterfall display?

以下哪项描述了瀑布显示？

Frequency is horizontal, signal strength is vertical, time is intensity

频率是水平方向，信号强度是垂直方向，时间是强度

Frequency is vertical, signal strength is intensity, time is horizontal

频率是垂直的，信号强度是强度，时间是水平的

Frequency is horizontal, signal strength is intensity, time is vertical

频率是水平方向，信号强度是强度，时间是垂直方向

✓ 正确答案

Frequency is vertical, signal strength is horizontal, time is intensity

频率是垂直的，信号强度是水平的，时间是强度

#G8C15🔗

What does an FT8 signal report of +3 mean?

FT8 信号报告 +3 是什么意思？

The signal is 3 times the noise level of an equivalent SSB signal

该信号是等效 SSB 信号噪声水平的 3 倍

The signal is S3 (weak signals)

信号为S3（弱信号）

The signal-to-noise ratio is equivalent to + 3dB in a 2 . 5 kHz bandwidth

信噪比相当于 2 中的 + 3dB。 5 kHz 带宽

✓ 正确答案

The signal is 3 dB over S9

信号比S9高3dB

#G8C16🔗

Which of the following provide digital voice modes?

以下哪项提供数字语音模式？

WSPR, MFSK16, and EasyPAL

WSPR、MFSK16 和 EasyPAL

FT8, FT4, and FST4

FT8、FT4 和 FST4

Winlink, PACTOR II, and PACTOR III

Winlink、PACTOR II 和 PACTOR III

DMR , D- STAR , and SystemFusion

DMR、D-STAR 和 SystemFusion

✓ 正确答案

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FCC G8C - 信号与发射模式

小节 G8C：信号与发射模式