CRAC Bilingual Manual › Part: Radio System Fundamentals
CRAC Bilingual Exam Manual (Class A / B / C) | 中国业余无线电台操作技术能力验证英中对照手册
This section covers Amateur Radio Satellites with 8 bilingual questions from the CRAC 2025 question bank. Each question shows the original Chinese (left) and the English translation (right). The correct answer is highlighted in green, followed by a Knowledge Point Analysis and Candidate Tips covering US–China differences, common pitfalls, and real on-air practice.
Class badges ABC indicate which license-class syllabus includes each question. Class A is the entry level, Class B adds HF privileges, and Class C is the advanced level.
在业余无线电领域中，缩写AMSAT是指：
- A美国的业余无线电卫星公司，是一个专注于实验卫星的设计、制造、运行和推进空间教育的非营利性志愿者组织
- B所有业余无线电卫星的总称
- C某一系列业余无线电卫星的总称
- D某一颗业余无线电卫星的名称
In the amateur radio field, the abbreviation AMSAT refers to:
- Athe American amateur radio satellite organization — a non-profit volunteer organization focused on the design, construction, operation of experimental satellites, and the promotion of space education
- Bthe general name for all amateur radio satellites
- Cthe general name for a certain series of amateur radio satellites
- Dthe name of a particular amateur radio satellite
AMSAT is the amateur radio satellite organization (originally Radio Amateur Satellite Corporation, now AMSAT) — a volunteer non-profit building and operating amateur satellites (A). It is not a satellite name or a generic class of satellites (B/C/D).
US–China difference: AMSAT has affiliated groups worldwide (e.g., AMSAT-UK, AMSAT-DL); the name denotes the organization, not a satellite.
Common pitfall: Assuming AMSAT is a satellite’s name rather than the building organization.
Real on-air practice: You work FM satellites like SO-50 or LEO birds built with AMSAT involvement.
在描述业余无线电卫星时经常用到缩写OSCAR（奥斯卡），这个名称的由来是：
- A“搭载有业余无线电装置的地球轨道卫星”的英文缩写
- B按照发明者奥斯卡的方案设计制造的业余卫星
- C纪念业余无线电技术先驱者奥斯卡
- D电影奥斯卡金奖的基金所赞助的业余卫星活动
When describing amateur radio satellites, the abbreviation OSCAR (奥斯卡) is often used. The origin of this name is:
- Athe English acronym of “Orbiting Satellite Carrying Amateur Radio” (a satellite in Earth orbit carrying amateur radio equipment)
- Ban amateur satellite designed and built according to the scheme of the inventor Oscar
- Cin memory of Oscar, a pioneer of amateur radio technology
- Damateur satellite activities sponsored by the fund of the Academy Award (Oscar) film prize
OSCAR stands for Orbiting Satellite Carrying Amateur Radio (A). It is an acronym, not a person’s name (B, C) nor related to the film Academy Award (D).
US–China difference: N/A — OSCAR is the international naming convention for amateur satellites.
Common pitfall: Thinking “Oscar” refers to a person or the movie award.
Real on-air practice: Satellites are numbered, e.g., FO-29, AO-7, HO-68 — the letter shows the country/region of origin.
我国发射的第一颗业余卫星的发射年份、名称、国际OSCAR系列号和转发器模式分别为：
- A2009年，希望一号（XW-1），HO68，V/U（J）
- B2008年，希望一号（XW-1），HO68，V/U（J）
- C2010年，希望一号（XW-1），HO68，V/U（J）
- D2008年，希望一号（XW-1），无OSCAR编号，B
The launch year, name, international OSCAR number, and transponder mode of China’s first amateur satellite are, respectively:
- A2009, Hope-1 (XW-1), HO68, V/U (J)
- B2008, Hope-1 (XW-1), HO68, V/U (J)
- C2010, Hope-1 (XW-1), HO68, V/U (J)
- D2008, Hope-1 (XW-1), no OSCAR number, B
China’s first amateur satellite is Hope-1 (希望一号, XW-1), launched in 2009, assigned OSCAR number 68 (HO-68), using a V/U (J) mode transponder — uplink VHF, downlink UHF, mode J (A). The other years (B, C, D) and “no OSCAR number” (D) are wrong.
US–China difference: The US has many OSCAR birds (e.g., AO-7, FO-29); China’s first was Hope-1/HO-68 in 2009.
Common pitfall: Mixing up the 2008/2009/2010 launch years.
Real on-air practice: You can still work some Chinese-built satellites on V/U FM or linear transponders.
开展EME通信试验的最佳时机是：
- A月亮处于近地点
- B满月
- C通信两端天气都好
- D太阳黑子数高
The best time to conduct EME (Earth-Moon-Earth / moonbounce) communication experiments is:
- Awhen the Moon is at perigee
- Bfull moon
- Cboth ends of the communication have good weather
- Dhigh sunspot number
EME path loss is enormous, so the best moment is when the Moon is closest to Earth — at perigee (A) — minimizing distance and thus path loss. Full moon (B) only affects illumination, not reflection gain; local weather (C) and sunspot count (D) are not the determining factors.
US–China difference: N/A — EME propagation physics is the same everywhere.
Common pitfall: Assuming full moon helps EME; it is perigee (closest approach) that matters.
Real on-air practice: EME operators schedule schedules around perigee windows for the strongest returns.
在EME通信等需要接收极微弱信号的场合，安装前置放大器时应做到：
- A尽量安装在靠近天线的地方，信号特别微弱时对放大器进行冷却以降低热噪声
- B尽量安装在靠近接收机的地方，放大器最好加热以防止元器件温度过低
- C尽量安装在靠近接收机的地方，放大器尽量采用较高的电源电压以求更高的增益
- D尽量安装在远离天线的地方，放大器采用射频正反馈电路以提高增益
When installing a preamplifier for occasions requiring reception of extremely weak signals, such as EME communication, you should:
- Ainstall it as close to the antenna as possible, and cool the amplifier to reduce thermal noise when the signal is especially weak
- Binstall it as close to the receiver as possible, and preferably heat the amplifier to prevent components from getting too cold
- Cinstall it as close to the receiver as possible, and use as high a supply voltage as possible for higher gain
- Dinstall it far from the antenna, and use an RF positive-feedback circuit in the amplifier to raise the gain
For weakest-signal reception, the low-noise preamplifier (LNA) must sit right at the antenna feed to beat the feed-line noise, and cooling lowers its thermal noise (A). Putting it near the receiver (B, C) or using feedback for gain (D) worsens the noise figure.
US–China difference: N/A — LNA-placement principles are universal.
Common pitfall: Mounting the preamp at the receiver end, letting the feed line add noise before amplification.
Real on-air practice: A masthead preamp for 2 m EME sits at the Yagi feed point.
对于需要接收VHF/UHF微弱信号的通信场景，比如月面反射实验，爱好者们时常需要在所用八木天线的馈电端处就近加装低噪声前置放大器。相比之下，HF通信爱好者却很少将他们所用的前置放大器装在八木天线或其他收信天线的馈电点处。这是因为：
- AVHF/UHF频段的背景噪声较HF频段为低。将放大器置于接收天线处可降低传输线固有噪声的影响，提高收信信噪比。而对于HF频段，是否这样做，差别并不明显
- B电缆的固有噪声在VHF/UHF频段更高
- CHF频段的放大器体积太大，不适合安装于天线端
- DHF频段的八木天线体积较大，把放大器装得太近容易引发自激
For communication scenarios needing reception of VHF/UHF weak signals, such as moonbounce experiments, amateurs often add a low-noise preamplifier right at the feed point of their Yagi antenna. In contrast, HF amateurs rarely mount their preamplifier at the feed point of a Yagi or other receiving antenna. This is because:
- Athe background noise in the VHF/UHF bands is lower than in the HF band. Placing the amplifier at the receiving antenna reduces the effect of the transmission line’s inherent noise and improves the received signal-to-noise ratio; for the HF band, whether you do this or not makes little difference
- Bthe inherent noise of the cable is higher in the VHF/UHF bands
- CHF-band amplifiers are too bulky to fit at the antenna end
- DHF-band Yagi antennas are large; placing the amplifier too close can easily cause self-oscillation
VHF/UHF external (galactic/atmospheric) noise is low, so receiver/feed-line noise dominates and a masthead LNA helps a lot (A). On HF the natural band noise is already high, so a front-end preamp barely improves the SNR — hence HF users seldom bother. B/C/D give wrong or trivial reasons.
US–China difference: N/A — the external-noise-vs-internal-noise reasoning is the same worldwide.
Common pitfall: Thinking HF also benefits strongly from a masthead preamp; often it does not.
Real on-air practice: On 144 MHz EME a masthead LNA is essential; on 20 m it’s usually unnecessary.
下列哪个业余波段最适合流星余迹散射通信？
- A6米
- B10米
- C2米
- D70厘米
Which of the following amateur bands is most suitable for meteor-scatter communication?
- A6 meters
- B10 meters
- C2 meters
- D70 centimeters
Meteor-scatter works best on the 6-meter band (A), where the ionized meteor trails efficiently reflect VHF signals at a favorable frequency/wavelength. Higher bands (2 m, 70 cm) and 10 m are less optimal for this mode.
US–China difference: N/A — 6 m meteor scatter is a worldwide technique.
Common pitfall: Guessing a higher VHF/UHF band instead of 6 m.
Real on-air practice: During meteor showers, operators use WSJT modes on 6 m to catch brief pings.
下列哪些通信方式可用于流星余迹和对流层散射通信实验？
- AFT4
- BAPRS
- CQPSK31
- DMT63
Which of the following communication modes can be used for meteor-scatter and tropospheric-scatter communication experiments?
- AFT4
- BAPRS
- CQPSK31
- DMT63
FT4 is a weak-signal, short-transmission WSJT mode well suited to the brief, fading reflections of meteor- and tropospheric-scatter (A). APRS (B) is a position-reporting system, QPSK31 (C) is not a standard weak-signal mode here, and MT63 (D) is a robust but not scatter-optimized mode; the official key marks A.
US–China difference: N/A — FT4/WSJT-X modes are used worldwide for scatter.
Common pitfall: Picking a routine mode (APRS) rather than a weak-signal WSJT mode.
Real on-air practice: During a meteor shower you may complete FT4 pings via ionized trails on 6 m.
💬 Have questions about this topic, or FCC / CRAC exam preparation?
对本篇内容或 FCC / CRAC 备考有疑问？
本手册仅供业余无线电爱好者学习交流，题库原题版权归 CRAC（中国无线电协会业余无线电分会）所有，英文翻译由 BG7BAG 编译，转载请注明出处。
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