Z3D153 - 2016 Edit Code 3, Volume 1 Part 3

When the modulating signal and carrier signal are combined within a modulator, the output signal contains the carrier signal along with the upper sideband and lower sideband. The upper sideband is the frequency range above the carrier frequency, while the lower sideband is the frequency range below the carrier frequency. This is a result of the modulation process where the modulating signal alters the amplitude, frequency, or phase of the carrier signal, creating these additional frequency components in the output signal.

The correct answer is straight through and crossover. Straight through cables are used to connect different types of devices, such as a computer to a switch or a router to a modem. The wires in these cables are connected in the same order on both ends. On the other hand, crossover cables are used to connect similar devices, such as a computer to another computer or a switch to another switch. In crossover cables, the wires are crossed over, so that the transmit and receive signals can be properly exchanged between the devices.

A guard band is a narrow frequency band that is used to prevent frequency modulated sidebands from overlapping. It acts as a buffer zone between adjacent stations, ensuring that there is no interference or signal overlap. By allocating a specific frequency range as a guard band, it helps maintain the integrity and clarity of the signals transmitted by different stations.

The three general categories used to produce modulation in radio frequency (RF) transmission today are amplitude, frequency, and phase. Modulation is the process of varying one or more properties of a carrier signal in order to transmit information. In amplitude modulation (AM), the amplitude of the carrier signal is varied to represent the information. In frequency modulation (FM), the frequency of the carrier signal is varied. In phase modulation (PM), the phase of the carrier signal is varied. These three modulation techniques are widely used in RF transmission to encode and transmit data.

The amount of effect or change that the intelligence has on the carrier in an amplitude modulated signal is expressed as the percent of modulation. This refers to the percentage of variation in the amplitude of the carrier signal caused by the modulation. It indicates the strength or intensity of the modulating signal and how much it influences the carrier signal. The higher the percent of modulation, the greater the impact of the modulating signal on the carrier signal.

The modulation index is a measure of the extent of modulation in a signal. It is calculated by dividing the peak frequency deviation by the modulating signal frequency. In this case, the modulating signal frequency is 5 kHz and the peak frequency deviation is 15 kHz. Therefore, the modulation index is 15 kHz / 5 kHz = 3. This means that the modulating signal is causing a frequency deviation that is three times its own frequency.

Parity is used by the receiving device in asynchronous transmissions to verify that the transmission was received correctly. Parity is a simple error-checking technique that involves adding an extra bit to each transmitted byte. The value of this extra bit is determined based on the number of 1s in the byte. When the receiving device receives the byte, it counts the number of 1s and compares it to the value of the parity bit. If they match, it indicates that the transmission was received correctly.

In synchronous transmission, data is transmitted in blocks. Each block of data includes multiple characters, which are composed of several bits. If an error occurs during transmission, it is possible for an entire block of data to be lost. Therefore, the correct answer is "Block of data."

When using forward error control as a method of error correction, error correction takes place at the receiving end. This means that the receiver is responsible for detecting and correcting errors that may have occurred during the transmission of data. By implementing forward error control at the receiving end, any errors that are detected can be corrected before the data is processed or displayed, ensuring the accuracy and integrity of the received information.

The spacing of the sidebands in an amplitude modulated signal is determined by the frequency of the modulating signal. In amplitude modulation, the modulating signal is superimposed onto the carrier signal, resulting in the creation of sidebands. These sidebands are located above and below the carrier frequency, and their spacing is directly proportional to the frequency of the modulating signal. Therefore, the higher the frequency of the modulating signal, the wider the spacing between the sidebands.

In frequency modulation (FM), the output of the oscillator increases in frequency with each positive half cycle of the modulating signal. This means that as the amplitude of the modulating signal increases during the positive half cycle, the frequency of the oscillator also increases. This results in a change in the frequency of the carrier signal, which is the basis of FM modulation.

The correct answer is a driver, optical source, and fiber optic pigtail. An optical transmitter is a device that converts electrical signals into optical signals for transmission over fiber optic cables. The driver is responsible for converting the electrical signal into a format suitable for the optical source, which generates the optical signal. The fiber optic pigtail is used to connect the optical source to the fiber optic cable, allowing the optical signal to be transmitted.

Quantization in the pulse code modulation process involves placing an infinite number of amplitude values to a finite number of values. This means that the continuous time signal is approximated by assigning discrete amplitude values to represent different levels of the signal. This allows for the efficient encoding and transmission of the signal while still maintaining a reasonable level of accuracy.

By adding more phase shifts, it allows for a larger number of distinct symbols to be transmitted within a given bandwidth. This means that more information can be transmitted per unit of time, resulting in higher data rates. This advantage is especially important in scenarios where there is limited bandwidth available, as it allows for more efficient use of the available resources.

The VRC (Vertical Redundancy Check) and LRC (Longitudinal Redundancy Check) methods, when used together, are 98 percent effective in detecting errors. The VRC is a simple parity check that adds an extra bit to each character to ensure the total number of 1s is either even or odd. The LRC is a more complex method that generates a parity bit for each character and then adds all the parity bits together. By combining these two methods, a high level of error detection can be achieved.

The correct answer is white, red, black, yellow, and violet. This is the correct order for the "tip" or "primary" wire color group in telecommunications cable. The colors blue, green, red, and orange are not part of the correct order.

When modulation is reduced to less than 100 percent, it means that the amplitude of the carrier signal is not fully varied. In this case, the carrier power remains constant and does not decrease. The reduction in modulation only affects the sideband power, which is the power carried by the frequency components surrounding the carrier signal. Therefore, the correct answer is that there is no reduction in carrier power.

Multimode step-index optical fiber cable has a bandwidth of 10 MHz – 100 MHz/km. This means that it is capable of transmitting data at frequencies ranging from 10 MHz to 100 MHz per kilometer of cable. The bandwidth determines the amount of data that can be transmitted over the cable, with higher bandwidths allowing for faster data transmission.

The significance of the amount of ones in a data bit pattern when using vertical redundancy check (VRC) is that it determines the parity. Parity refers to the number of ones in a data bit pattern. VRC is a simple method of error detection in which an additional bit, called the parity bit, is added to the data. The parity bit is set to 1 or 0 in a way that ensures the total number of ones (including the parity bit) is always even or odd. By checking the parity bit, errors in transmission can be detected.

The first step in the pulse code modulation process is to band limit the analog signal. This means that the signal is filtered to remove any frequencies outside of a certain range. This is done to ensure that the signal can be accurately represented using discrete amplitudes and binary code numbers. By band limiting the signal, it becomes easier to assign discrete amplitudes to the sampling pulses and to assign binary code numbers to the samples. This is because the band limited signal has a reduced range of frequencies, making it simpler to represent digitally.