# FREE Registered Communications Distribution Designer (RCDD): Network Design Principles and Practice Questions and Answers

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#### In a scenario where a video camera provides a video signal through a coaxial cable output and the intention is to transmit the signal to devices equipped with balanced twisted pair inputs, how can the conversion between these dissimilar transmission media be effectively achieved?

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The correct answer is Balun. A balun (balanced to unbalanced) is a device used to convert signals between balanced and unbalanced transmission lines. In this context, when transitioning from a coaxial cable output of the video camera to devices with balanced twisted pair inputs, a balun is employed to facilitate the seamless conversion and match the impedance levels between the different transmission mediums. It allows for efficient signal transfer without distortion.

#### An illustration of which kind of system is found in the public telephone system?

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The correct answer is Full-duplex. The public telephone system operates using a full-duplex communication mode, allowing simultaneous transmission and reception of signals. This enables both parties in a conversation to communicate at the same time without interruption, akin to a natural conversation. This choice provides efficient and effective two-way communication in scenarios such as phone calls.

#### If a communication system receives an input signal power of 1 watt and produces an output power of 1 milliwatt, what is the measure of system attenuation?

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The correct answer is 30 dB. Attenuation is a measure of signal loss in a communication system. In this scenario, the output power is 1 milliwatt, which is 0.001 watts. The input power is 1 watt. By calculating the ratio of output power to input power in decibels (dB), we get 10 * log10(0.001/1) = -30 dB, indicating a 30 dB attenuation, meaning the signal's power has decreased by 30 dB during transmission.

#### When considering slip sleeves or gutters, which of the following statements accurately reflects their characteristics or attributes?

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The correct answer is Provides more space for pulling. Slip sleeves or gutters serve the purpose of creating additional room to facilitate the pulling of cables through them. They are designed to offer increased space, aiding in the smooth and efficient installation of cables. This characteristic is especially valuable when dealing with larger cables or complex installation scenarios where ease of cable placement is paramount.

#### Given a balanced twisted pair cable with an input signal strength of 10 milliwatts, and considering that the cable extends for a length of 1000 feet with an attenuation rate of 1 decibel per 100 feet, what would be the signal-to-noise ratio (SNR) in decibels at the input of the receiver?

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The correct answer is 30 dB. In this scenario, the signal travels through a 1000-foot cable with an attenuation rate of 1 decibel per 100 feet. The total attenuation for the entire length of the cable would be 10 dB. Given that the input signal is 10 mW (or 10 dBm), and the noise level is 1 microwatt (or 0 dBm), the signal-to-noise ratio (SNR) can be calculated as 10 dBm - 0 dBm - 10 dB = 0 dB. However, since decibels are used logarithmically, the negative result indicates a loss of 10 dB, which is added back to the noise level of 0 dBm. This gives us an SNR of 10 dBm, or 10 dB.

#### Given that an existing ceiling raceway system possesses 115,000 square millimeters (177 square inches) of cross-sectional area intended for the distribution of cable runs, what is the maximum number of cable runs that can be accommodated by this pre-existing system?

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The correct answer is 177. The existing ceiling raceway system, with its available cross-sectional area of 115,000 square millimeters (177 square inches), can accommodate up to 177 cable runs. This calculation is based on the available space within the raceway and ensures efficient cable distribution without exceeding the given area.

#### In a situation where CAT6 cable installation is required above a factory floor housing automated welding machines and hammer forges, which among the following choices for shielding would offer the highest degree of effectiveness?

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The correct answer is Solid metallic conduit. In an environment with intense electromagnetic interference generated by automated welding machines and hammer forges, solid metallic conduit provides a robust shield against such interference. Its grounded metal construction effectively mitigates the potential for electromagnetic interference to disrupt the transmission of signals through the CAT6 cable. This shielding choice ensures a high level of protection and reliability for the communication system.