FCC E4E - 业余电台实践与测试

#E4E01🔗

What problem can occur when using an automatic notch filter (ANF) to remove interfering carriers while receiving CW signals?

在接收 CW 信号时使用自动陷波滤波器 (ANF) 去除干扰载波会出现什么问题？

Removal of the CW signal as well as the interfering carrier

去除 CW 信号以及干扰载波

✓ 正确答案

Any nearby signal passing through the DSP system will overwhelm the desired signal

任何附近通过 DSP 系统的信号都会压倒所需信号

Excessive ringing

铃声过多

All these choices are correct

所有这些选项都是正确的

#E4E02🔗

Which of the following types of noise can often be reduced by a digital noise reduction?

以下哪种类型的噪声通常可以通过数字降噪来降低？

Broadband white noise

宽带白噪声

Ignition noise

点火噪音

Power line noise

电源线噪声

All these choices are correct

所有这些选项都是正确的

✓ 正确答案

#E4E03🔗

Which of the following types of noise are removed by a noise blanker?

噪声消除器可以消除以下哪种类型的噪声？

Broadband white noise

宽带白噪声

Impulse noise

脉冲噪声

✓ 正确答案

Hum and buzz

嗡嗡声和嗡嗡声

All these choices are correct

所有这些选项都是正确的

#E4E04🔗

How can conducted noise from an automobile battery charging system be suppressed?

如何抑制汽车电池充电系统的传导噪声？

By installing filter capacitors in series with the alternator leads

通过与交流发电机引线串联安装滤波电容器

By installing a noise suppression resistor and a blocking capacitor at the battery

通过在电池处安装噪声抑制电阻和隔直电容器

By installing a high-pass filter in series with the radio’s power lead and a low-pass filter in parallel with the antenna feed line

通过安装与无线电电源线串联的高通滤波器和与天线馈线并联的低通滤波器

By installing ferrite chokes on the charging system leads

通过在充电系统引线上安装铁氧体扼流圈

✓ 正确答案

#E4E05🔗

What is used to suppress radio frequency interference from a line-driven AC motor?

用什么来抑制线驱动交流电机的射频干扰？

A high-pass filter in series with the motor’s power leads

与电机电源线串联的高通滤波器

A brute - force AC-line filter in series with the motor’s power leads

与电机电源线串联的强力交流线路滤波器

✓ 正确答案

A bypass capacitor in series with the motor’s field winding

与电机励磁绕组串联的旁路电容器

A bypass choke in parallel with the motor’s field winding

与电机励磁绕组并联的旁路电抗器

#E4E06🔗

What type of electrical interference can be caused by computer network equipment?

计算机网络设备会引起什么类型的电气干扰？

A loud AC hum in the audio output of your station’s receiver

电台接收器的音频输出中有很大的交流嗡嗡声

A clicking noise at intervals of a few seconds

每隔几秒就会发出咔哒声

The appearance of unstable modulated or unmodulated signals at specific frequencies

在特定频率出现不稳定的调制或未调制信号

✓ 正确答案

A whining-type noise that continually pulses off and on

持续断断续续的呜呜声

#E4E07🔗

Which of the following can cause shielded cables to radiate or receive interference?

以下哪项会导致屏蔽电缆辐射或接收干扰？

Low inductance ground connections at both ends of the shield

屏蔽层两端的低电感接地连接

Common-mode currents on the shield and conductors

屏蔽层和导体上的共模电流

✓ 正确答案

Use of braided shielding material

使用编织屏蔽材料

Tying all ground connections to a common point resulting in differential-mode currents in the shield

将所有接地连接连接到一个公共点，从而在屏蔽层中产生差模电流

#E4E08🔗

What current flows equally on all conductors of an unshielded multiconductor cable?

在非屏蔽多芯电缆的所有导体上均匀流动的电流是多少？

Differential-mode current

差模电流

Common -mode current

共模电流

✓ 正确答案

Reactive current only

仅无功电流

Magnetically-coupled current only

仅磁耦合电流

#E4E09🔗

What undesirable effect can occur when using a noise blanker?

使用噪声消除器时会产生什么不良影响？

Received audio in the speech range might have an echo effect

在语音范围内接收到的音频可能会产生回声效应

The audio frequency bandwidth of the received signal might be compressed

接收信号的音频带宽可能被压缩

Strong signals may be distorted and appear to cause spurious emissions

强信号可能会失真并可能导致杂散发射

✓ 正确答案

FM signals can no longer be demodulated

FM 信号无法再解调

#E4E10🔗

Which of the following can create intermittent loud roaring or buzzing AC line interference?

以下哪项会产生间歇性的大声轰鸣或嗡嗡声交流线路干扰？

Arcing contacts in a thermostatically controlled device

恒温控制设备中的电弧触点

A defective doorbell or doorbell transformer inside a nearby residence

附近住宅内的门铃或门铃变压器有缺陷

A malfunctioning illuminated advertising display

故障的照明广告显示屏

All these choices are correct

所有这些选项都是正确的

✓ 正确答案

#E4E11🔗

What could be the cause of local AM broadcast band signals combining to generate spurious signals on the MF or HF bands?

本地 AM 广播频段信号组合在 MF 或 HF 频段上产生杂散信号的原因是什么？

One or more of the broadcast stations is transmitting an over-modulated signal

一个或多个广播电台正在传输过调制信号

Nearby corroded metal connections are mixing and reradiating the broadcast signals

附近腐蚀的金属连接正在混合并重新辐射广播信号

✓ 正确答案

You are receiving skywave signals from a distant station

您正在接收来自远程站的天波信号

Your station receiver IF amplifier stage is overloaded

您的电台接收器中频放大器级过载

#E4E12🔗

What causes interference received as a series of carriers at regular intervals across a wide frequency range?

是什么导致在很宽的频率范围内以固定间隔接收到一系列载波的干扰？

Switch - mode power supplies

开关电源

✓ 正确答案

Radar transmitters

雷达发射机

Wireless security camera transmitters

无线安全摄像头发射器

Electric fences

电子围栏

#E4E13🔗

Where should a station AC surge protector be installed?

电站交流电涌保护器应安装在哪里？

At the AC service panel

在空调服务面板上

At an AC outlet

在交流电源插座上

On the single point ground panel

在单点接地板上

✓ 正确答案

On a ground rod outside the station

在车站外的接地棒上

#E4E14🔗

What is the purpose of a single point ground panel?

单点接地板的用途是什么？

Remove AC power in case of a short-circuit

发生短路时断开交流电源

Prevent common-mode transients in multi-wire systems

防止多线系统中的共模瞬态

Eliminate air gaps between protected and non-protected circuits

消除受保护电路和未受保护电路之间的气隙

Ensure all lightning protectors activate at the same time

确保所有防雷器同时激活

✓ 正确答案

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FCC E4E - 业余电台实践与测试

小节 E4E：业余电台实践与测试