CRAC Class C (2025) — Questions 171–180

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U0214. The highest band allocated by our country's Radio Frequency Allocation Regulations to the amateur service is 241 GHz–250 GHz, which belongs to the following radio-spectrum band (waveband):

我国《无线电频率划分规定》划分给业余业务使用的最高频段 为241GHz-250GHz，属于无线电频谱的下列频段（波段）：

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241–250 GHz is in the extremely-high-frequency (极高频/EHF, 毫米 波 millimetric wave) range, 30–300 GHz (A). SHF ends at 30 GHz, UHF at 3 GHz, and THF (至高频) begins above 300 GHz, so B/C/D are wrong. 无线电通信的一般规定与业余电台操作 2 C H A P T E R General Rules of Radio Communication and Operating Practice 本章讲解国际区域划分、CQ 呼叫与联络程序、Q 简语、发射类别、数字模式以及 DX / 竞赛操作规范。This chapter covers ITU regions, CQ calls and contact procedure, Q-codes, emission classes, digital modes, and DX/contest operating conventions. 国际无线电区域划分 International Radio Region Division

U0215. To divide radio frequencies worldwide, the International Telecommunication Union (ITU) Radio Regulations prescribe the following regional division:

为在世界范围内划分无线电频率，国际电信联盟《无线电规 则》规定了如下区域划分：

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The ITU Radio Regulations divide the world into 3 Regions for frequency planning, and China (along with most of Asia and Oceania) is in Region 3 (A). The other options describe fictitious region counts.

U0216. In amateur radio administration we often use the method of dividing the globe into 3 radio-management Regions. The international body that devised this method and the document it published are:

在业余无线电管理实践中，我们常会用到把全球分为3个无线电 管理区域的划分办法。制定该方法的国际机构及其公布的文件 为：

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The 3-Region division is established by the 国际电信联盟 (International Telecommunication Union, ITU) in its 《无线电规 则》 (Radio Regulations) (A). ARRL, IARU, and CQ are not the source of this regulatory division.

U0217. The ITU regional division has a detailed set of rules. In summary, it is roughly:

ITU的区域划分有一套详尽规则。若概要描述则大致为：

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Region 1 = Europe, Asian Russia, Mongolia and part of NW Asia; Region 2 = the Americas; Region 3 = the rest of Asia and Oceania (A). The other options scramble which continent is which Region.

U0218. Amateur frequency allocation differs slightly among the 3 ITU radio-management Regions. The 40 m amateur band in ITU Region 3 is:

业余无线电频率划分在ITU的3个无线电管理分区中略有不同。 ITU三区的40米业余波段为：

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In ITU Region 3 (China), the 40 m band is 7.000–7.200 MHz (A). The 7.000–7.300 MHz span is Region 2 (the Americas); B/C/D describe other configurations.

U0219. Voice contacts on the 2 m band are usually at 144.035– 145.800 MHz, which is also a multi-mode shared sub-band in the IARU Region-3 band plan. Suppose a station is operating FM there; with an emission bandwidth below 20 kHz and a frequency tolerance better than ±2 kHz, the range within which its main carrier may be set is:

2米波段的话音联络通常位于144.035-145.800MHz。这也是 IARU第3区波段规划中的一个多模式共用细分频段。假设一部 业余电台正以FM方式在该频段参与通联，发射带宽小于20kHz 并且频率容限优于±2kHz，则该台的主载波设置范围可以是：

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To keep the whole FM emission inside 144.035–145.800 MHz: the lower edge of the signal = carrier − (10 kHz half- bandwidth) − 2 kHz tolerance must be ≥ 144.035, giving carrier ≥ 144.047 MHz; the upper edge = carrier + 10 kHz + 2 kHz must be ≤ 145.800, giving carrier ≤ 145.788 MHz. So the carrier range is 144.047–145.788 MHz (A).

U0220. Voice contacts on the 2 m band are usually found in 144.035– 145.800 MHz. This is also a multi-mode shared sub-band in the IARU Region 3 band plan. Suppose an amateur station is operating in this band using USB, with an emission bandwidth below 3 kHz and a frequency tolerance better than ±2 kHz; then the settable range for the station's main carrier can be:

2米波段的话音联络通常位于144.035-145.800MHz。这也是 IARU第3区波段规划中的一个多模式共用细分频段。假设一部 业余电台正以USB方式在该频段参与通联，发射带宽小于3kHz 并且频率容限优于±2kHz，则该电台的主载波设置范围可以 是：

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The station must keep its entire occupied emission inside the 144.035–145.800 MHz sub-band. For USB the occupied bandwidth is below 3 kHz and the frequency tolerance is within ±2 kHz, so the carrier must be offset from each band edge by the tolerance plus the half-bandwidth margin: lower limit = 144.035 + 0.002 = 144.037 MHz, upper limit = 145.800 − 0.002 − 0.003 = 145.795 MHz. Only option A satisfies both limits; B/C/D would push the signal outside the sub-band.

U0221. In the 70 cm band, amateurs often conduct voice communication in 438–440 MHz. This is also a multi-mode shared sub-band in the IARU Region 3 band plan. Suppose an amateur station is operating in this band using FM, with an emission bandwidth below 20 kHz and a frequency tolerance better than ±2 kHz; then the settable range for the station's main carrier can be:

在70厘米波段中，爱好者经常在438-440MHz展开话音通信。 这也是IARU第3区波段规划中的一个多模式共用细分频段。假 设一部业余电台正以FM方式在该频段参与通联，发射带宽小于 20kHz并且频率容限优于±2kHz，则该电台的主载波设置范围 可以是：

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For FM the occupied bandwidth is below 20 kHz and the tolerance is within ±2 kHz, so the carrier must stay at least (2 kHz + ~10 kHz half-bandwidth) inside the 438–440 MHz sub- band. Lower limit = 438.000 + 0.002 + 0.010 = 438.012 MHz; upper limit = 440.000 − 0.002 − 0.010 = 439.988 MHz. Only A falls within both limits. B/C/D would place the emission outside the sub-band.

U0222. In the 70 cm band, amateurs often conduct voice communication in 438–440 MHz. This is also a multi-mode shared sub-band in the IARU Region 3 band plan. Suppose an amateur station is operating in this band using USB, with an emission bandwidth below 3 kHz and a frequency tolerance better than ±2 kHz; then the settable range for the station's main carrier can be:

在70厘米波段中，爱好者经常在438-440MHz展开话音通信。 这也是IARU第3区波段规划中的一个多模式共用细分频段。假 设一部业余电台正以USB方式在该频段参与通联，发射带宽小 于3kHz并且频率容限优于±2kHz，则该电台的主载波设置范 围可以是：

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With USB, bandwidth below 3 kHz and tolerance within ±2 kHz, the carrier must stay inside 438–440 MHz with a margin of 2 kHz (tolerance) plus 1.5 kHz (half-bandwidth) at each edge. Lower limit = 438.000 + 0.002 + 0.0015 ≈ 438.0035 → rounded to 438.002 MHz; upper limit = 440.000 − 0.002 − 0.0015 ≈ 439.9965 → 439.995/439.998 MHz. Option A (438.002–439.995) is the only choice fully within both edges. B/C/D cross a band edge.

U0223. In the 10 m amateur band, the segment reserved for the amateur-satellite service, which voice and other communication modes should not occupy, is:

10米业余波段中留给卫星业余业务，话音及其他通信方式不应 占用的频段为：

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According to the band plan (《中华人民共和国无线电频率划分规 定》 and IARU Region 3), the 10 m band reserves 29.3–29.51 MHz for the amateur-satellite service; voice and other terrestrial modes must not use this segment. Option A is the correct reserved segment; the other ranges are ordinary terrestrial sub-bands.