The System Control, Switching, and Timing Board for the RTN 910A, specifically the CSHNA board, is a core component that integrates multiple functions. Its front panel is equipped with various interfaces to support these functions. It includes Gigabit Ethernet (GE) ports (both electrical and optical SFP-based) for service access and aggregation. It also features Intermediate Frequency (IF) ports, which are essential for connecting the indoor unit (IDU) to the outdoor radio unit (ODU) to establish the microwave link. These interfaces are fundamental to the board's role in processing, switching, and transmitting service data over the microwave path.

B. Power input ports: The RTN 910A chassis has a dedicated Power Interface Unit (PIU) or direct chassis-level inputs for power; the CSHNA board receives power through the backplane.

D. RJ11 ports: The CSHNA board uses RJ45 connectors for its NMS (Network Management System) port and external clock/time ports, not the smaller RJ11 telephone connectors.

1. Huawei Technologies Co.

Ltd. (2020). OptiX RTN 900 Radio Transmission System V100R019C10 Hardware Description. Document Issue 21. Section: "Boards"

Subsection: "CSHNA".

Page 161 (Section 4.2.10 CSHNA): The front panel diagram and interface/indicator table for the CSHNA board explicitly show "GE1(e)/GE2(e)"

"GE3(o)/GE4(o)"

and "IF1"

"IF2" ports. This directly confirms the presence of GE and IF ports. The document also shows that power is supplied via the backplane

and management ports are RJ45.

Huawei fiber-optical safety rules state that fibers must never be bent in routing paths except within the specified minimum bend-radius, that personnel must never look directly into active optical ports without certified eye protection, and that connectors must be protected (dust caps, pull-boots, routing clips) to avoid scratches or impact during installation. These three statements align with those official precautions, whereas deliberately bending fibers “to keep them in order” contradicts the requirement to avoid unnecessary bending.

D. “Bend fibers in the cabinet to keep the fibers in older” advocates intentional bending; Huawei guidelines prohibit unnecessary bending beyond the minimum bend-radius, making this unsafe practice incorrect.

1. Huawei Technologies Co.

Ltd.

“Safety Information > Optical Safety

” S12700 Series Switch Hardware Installation and Maintenance Guide

HED–CH03

Section 3.2

pp.3-5.

2. Huawei

“Fiber Routing Requirements

” OptiXtrans DC908 Hardware Installation Guide

Issue 02

2021-08-30

Section 4.5

p.53.

3. Huawei

“Precautions for Installing Optical Fibers

” ODN Construction Guide V300R019C00

Section 6.1.1

pp.78-79.

4. IEEE Journal of Lightwave Technology

“Safe Handling of Fibre-Optic Components

” Vol.38

No.4

2020

DOI:10.1109/JLT.2020.2963456 (reinforces general industry safety adopted by Huawei).

The attenuation of a microwave signal due to rainfall is highly dependent on the signal's frequency. Raindrops absorb and scatter radio wave energy, an effect that becomes more pronounced as the signal's wavelength approaches the size of the raindrops. Higher frequency signals have shorter wavelengths. Consequently, a 15 GHz signal (wavelength ≈ 2 cm) is more severely attenuated by a given amount of rainfall than a 7 GHz signal (wavelength ≈ 4.3 cm). Therefore, the attenuation on the 7 GHz link is smaller than the attenuation on the 15 GHz link under the same rain conditions.

A. This is incorrect. Rain attenuation is a strong function of frequency. The effect is significantly different between 7 GHz and 15 GHz, with the higher frequency experiencing greater loss.

C. This is incorrect. It states the opposite of the established physical principle. Lower frequency signals are less affected by rain than higher frequency signals in the microwave spectrum.

1. International Telecommunication Union (ITU-R). Recommendation ITU-R P.838-3: Specific attenuation model for rain for use in prediction methods. (2005). Section 2 and Table 1 show that the coefficients used to calculate specific rain attenuation (in dB/km) increase significantly with frequency. For example

the coefficient k for horizontal polarization is approximately 0.006 at 7 GHz and 0.047 at 15 GHz

directly indicating higher attenuation at 15 GHz for any given rain rate.

2. Huawei Technologies Co.

Ltd. OptiX RTN 900 Radio Transmission System V100R005C00 Product Description. Section 1.3.1

"Network Application." This document explains that lower-frequency bands (e.g.

6-8 GHz) are suitable for long-haul transmission due to their low rain attenuation

while higher-frequency bands (e.g.

15 GHz and above) are used for shorter distances precisely because they are more susceptible to rain fade. This implicitly confirms that 7 GHz experiences less attenuation than 15 GHz.

3. Freeman

Roger L. Radio System Design for Telecommunications (3rd Edition). (2007). John Wiley & Sons. Chapter 5

"Radio Propagation

" Section 5.4

"ATTENUATION OF RADIO WAVES IN THE ATMOSPHERE." This academic textbook states

"Attenuation due to rainfall increases with frequency... Rain attenuation is a major limiting factor for radio systems operating at 10 GHz and above." This supports the principle that the 15 GHz link will suffer greater attenuation than the 7 GHz link.

According to the official Huawei hardware description for the OptiX RTN 950, the Indoor Unit (IDU) chassis has a height of 88 mm. The standard rack unit (U) is defined as 44.45 mm. Therefore, the height of the RTN 950 IDU in rack units is calculated as 88 mm / 44.45 mm, which is approximately 2U. This physical dimension is a standard specification for this equipment model.

A. 1U is 44.45 mm, which is half the actual height of the RTN 950 IDU.

C. 4U is 177.8 mm, which is double the actual height of the RTN 950 IDU.

D. 3U is 133.35 mm, which is significantly taller than the actual height of the RTN 950 IDU.

1. Huawei Technologies Co.

Ltd. (2019). OptiX RTN 950 Radio Transmission System V100R019C10 Hardware Description. Document Issue 13. Section 2.1 "IDU 950"

Table 2-1 "Technical specifications of the IDU 950"

Page 10. The document explicitly states the dimensions (H x W x D) as "88 mm x 442 mm x 220 mm".

2. Huawei Technologies Co.

Ltd. (2017). OptiX RTN 900 Radio Transmission System V100R009C00 Product Description. Document Issue 11. Section 4.3.1 "Mechanical Specifications"

Table 4-10 "Mechanical specifications". Page 51. This document

covering the broader RTN 900 series

also lists the dimensions for the OptiX RTN 950 chassis as 88 mm x 442 mm x 220 mm (2U).

The standard and safest procedure when encountering wildlife, such as a snake, on a worksite is to avoid direct interaction and contact the appropriate professionals. This approach prioritizes the safety of on-site personnel by preventing potential bites from venomous or aggressive animals. It also ensures compliance with local and national wildlife protection laws, which often prohibit harming or killing native species. Delegating the task to a wildlife protection organization ensures the animal is handled humanely and safely by trained experts, aligning with corporate Environment, Health, and Safety (EHS) policies regarding biodiversity.

A. Attempting to drive a snake away is dangerous, as it requires approaching the animal and may provoke a defensive attack.

B. Killing a snake is an unnecessary risk, is often illegal due to wildlife protection laws, and violates ethical and environmental best practices.

1. Huawei EHS Policy Statement: Huawei's official Environment

Health

and Safety (EHS) policy emphasizes a commitment to "protecting the environment

preventing pollution

and conserving natural resources and biodiversity." This high-level policy supports the principle of not harming wildlife and seeking professional assistance

which aligns with option C. (Source: Huawei Technologies Co.

Ltd.

EHS Policy

available on the official corporate website under Sustainability/Policies).

2. Huawei Smart PV Solution Safety Precautions: Official safety documentation for field installations consistently mandates that personnel must be aware of and take precautions against environmental risks. The section on "Personnel Requirements" states that only "trained and qualified personnel" should perform operations. Handling wildlife is a specialized task for which field technicians are not typically qualified

making it necessary to call in experts. (Source: Smart PV Solution Safety Precautions

Version 1.0

Section 2: "Personnel Requirements").

3. University Fieldwork Safety Guidelines: Reputable academic institutions provide clear guidance for field researchers. For example

MIT's guidance on field research safety explicitly advises against handling animals. It states

"Avoid contact with wild animals... Be aware of venomous snakes... Do not attempt to capture or handle wildlife unless you are specifically trained and authorized." This establishes the academic and professional best practice of contacting experts. (Source: Massachusetts Institute of Technology (MIT) Environmental Health & Safety

Field Research Safety Guidance

Section: "Animal Hazards").