Question 1

Which electrical characteristic is displayed with the correct preferred value?

Accepted Answer

A

Question 2

Which of the following is NOT a form of signal coupling between two (2) circuits?

Accepted Answer

Reactive coupling is not a form of signal coupling between two circuits. The other choices, conductive, inductive, capacitive, and electromagnetic are all commonly used forms of signal coupling.

Question 3

Assume that the optical power transmitted by a 62.5/125 multimode fiber is distributed uniformly across its core. If this fiber is perfectly coupled (i.e., the two fibers are aligned and abutted) to a 50/125 fiber, what is the percent of power that is lost?

Accepted Answer

The power loss is due to the difference in core areas. The 62.5/125 fiber has a larger core area than the 50/125 fiber. The power loss is calculated as the ratio of the core areas: (1 - (50/62.5)^2) * 100% = 36%.

Question 4

Wave division multiplexing (WDM) is most similar to:

Accepted Answer

Wave division multiplexing (WDM) is a technology used in fiber optic communication systems that enables the transmission of multiple signals simultaneously over a single optical fiber by using different wavelengths of light to carry different signals. This is similar to frequency division multiplexing (FDM), which uses different frequencies instead of wavelengths to separate multiple signals on a single transmission medium. Therefore, the best choice is D, frequency division multiplexing.

Question 5

All of the following are nominal wavelengths for laser light sources EXCEPT:

Accepted Answer

All of the other wavelength options (B, C, D, E) are commonly used in laser applications, particularly in fiber optic communications. 700 nm, however, is in the visible spectrum and not typically used for laser light sources.

Question 6

Optical transmitters are typically one of the following types EXCEPT:

Accepted Answer

Overfilled launch (OFL) is not a type of optical transmitter; it is a method of launching light into a fiber optic cable.

Question 7

Which characteristic is an advantage of copper based media over optical fiber cable?

Accepted Answer

Copper-based media can handle analog signals directly, which is an advantage over optical fiber that primarily handles digital signals.

Question 8

You must place CAT6 cable above a factory floor with automated welding machines and hammer forges. Of the following, what type of shielding would be most effective?

Accepted Answer

Solid metallic conduit would provide the most effective shielding in this scenario as it offers complete protection from electromagnetic interference and physical damage from machinery. Multi-layer braid and foil and braid shielding may not provide sufficient protection from the heavy machinery present in the factory, while flex metallic conduit and PVC conduit are not as durable and may not withstand the harsh environment.

Question 9

Composite conductors, although not generally recommended, may be used in special circumstances because they provide all of the following advantages EXCEPT:

Accepted Answer

Composite conductors do not have good digital transmission characteristics because they are not as efficient at transmitting high-frequency signals as solid conductors.

Question 10

Which is an advantage of stranded conductors over solid conductors?

Accepted Answer

Stranded conductors are more flexible than solid conductors, making them easier to bend and install in tight spaces.

Question 11

You must place a cable between 2 equipment locations with separate grounds having a potential difference between them of 2.1 V rms. Which one of the following cables should NOT be used?

Accepted Answer

The answer of You must place a cable between 2...

Question 12

A reasonable approximation for the signal speed in 100 ohm balanced twisted pair cable is __________, where c is the velocity of light in free space.

Accepted Answer

The signal speed in a balanced twisted pair cable is slower compared to free space due to the dielectric material surrounding the wires. The dielectric material in a twisted pair cable is typically plastic or rubber, with a relative permittivity (εr) of around 2.2-2.7. The velocity factor (VF) is the ratio of the speed of the signal in the cable to the speed of light in free space, and is given by VF = 1/√(εr). For a cable with an εr of 2.5 (typical for twisted pair cables), the VF is approximately 0.8. Therefore, the signal speed in the cable is 0.8 times the speed of light in free space (c), which gives a reasonable approximation of 0.6c.

Question 13

A video camera has a coaxial cable output. The video signal is to be distributed to devices that have balanced twisted pair inputs. The transition between these two different transmission media can be accomplished by using a:

Accepted Answer

A balun (short for balanced-unbalanced) is a device that converts between balanced and unbalanced signals. In this case, the coaxial cable output of the video camera is an unbalanced signal, while the devices with twisted pair inputs require a balanced signal. By using a balun, the unbalanced signal can be converted to a balanced signal for distribution to the other devices.

Question 14

Time division multiplexing (TDM) systems are designed to transport ________ between end point systems.

Accepted Answer

The answer of Time division multiplexing (TDM) systems are designed...

Question 15

If the input signal power to a communication system is 1 W and the output power is 1 mW, the system attenuation is:

Accepted Answer

Attenuation in dB is calculated using the formula: 10 * log10(Pout/Pin). Here, Pout = 1 mW = 0.001 W and Pin = 1 W. So, attenuation = 10 * log10(0.001/1) = 10 * log10(0.001) = 10 * (-3) = -30 dB. Since attenuation is a reduction, we take the absolute value, which is 30 dB.

Question 16

A SONET OC-1 channel can carry 672 voice signals and has a data rate of 51.84 Mbps. A SONET OC-48 channel can carry 32,256 voice channels. What MINIMUM data rate is required for the OC-48 channel?

Accepted Answer

The OC-48 channel carries 48 times the data of an OC-1 channel. Since an OC-1 channel has a data rate of 51.84 Mbps, the OC-48 channel requires a minimum data rate of 48 * 51.84 Mbps = 2.48832 Gbps, which is closest to 2.5 Gbps.

Question 17

The conversion of an analog speech signal to a pulse code modulation (PCM) digital signal involves all of the following steps EXCEPT:

Accepted Answer

Amplitude modulation is not involved in the conversion of an analog speech signal to a PCM digital signal. The other steps listed are all part of the process. Low pass filtering removes any high-frequency components above the Nyquist frequency to prevent aliasing, periodic sampling takes regular samples of the signal, quantizing discretizes the sample values into digital levels, and companding reduces the quantization error by applying a nonlinear compression and expansion to the signal.

Question 18

Two sinusoidal signals have the same amplitude (A) and the same frequency (f). They differ in phase by 180 degrees. If these two signals are added together, the result is a sinusoidal signal having an amplitude of:

Accepted Answer

When two sinusoidal signals with the same amplitude and frequency but differing in phase by 180 degrees are added together, they cancel each other out, resulting in a signal with zero amplitude.

Question 19

The signal at the input to a balanced twisted pair cable is 10 mW. The cable is 1000 feet long and has an attenuation of 1 dB per 100 feet. This cable is connected to the input of a receiver. The noise level at the input to the receiver is 1 microwatt. What is the signal-to-noise ratio (SNR) (dB) at the receiver input?

Accepted Answer

The signal loses 10 dB over 1000 feet (1 dB per 100 feet). The input signal is 10 mW, which is 10 dBm. After 10 dB attenuation, the signal is 0 dBm (1 mW). The noise level is 1 microwatt (0.001 mW), which is -30 dBm. The SNR is 0 dBm - (-30 dBm) = 30 dB.

Question 20

The public telephone system is an example of a __________ system.

Accepted Answer

The public telephone system is a full-duplex system, allowing simultaneous two-way communication.

Exam 1: BICSI Registered Communications Distribution Designer - RCDD