ESAT COACHING 3

The propagation is from a source (radio transmitter) to a load (radio receiver) where wave propagation is carried out through free space. The separation between the source and the load could be very large e.g. thousands of kms as in cellular communication or small (few kms) as in microwave communication within a city. This type of wave propagation is called ______.

In some applications the information has to be conveyed from one point to the other through connecting wires. Telephone lines from a telephone subscriber to the telephone exchange or vice versa. Connection between a radio transmitter and its antenna or a connection between an antenna and a radio receiver. This type of propagation is called _______.

A _____ is a conductive method of guiding electrical energy from one place to another. It is employed not only to transmit energy, but also as circuit elements like inductors, capacitors, resonant circuits, filters, transformers and even insulators at very high frequencies. Also used as measuring devices and as an aid to obtain impedance matching.

The nature of transmission line and its performance depends upon:

Transmission lines are categorized as:

Lines used for transmission of large quantities of power over a fixed frequency.

Used for transmission of small quantities of power over a band of frequencies.

These lines are the parallel conductors open to air. The conductors are separated by air as the dielectric are rigidly supported by cross arms put at a certain height from ground by means of galvanized iron poles or any other structure.

Electrical energy propagating through transmission lines set up electric fields between line conductors. These fields are at right angles to each other and to the direction of propagation which is along the length of the line. This type of energy transmission is known as

The radiation loss in an open two wire line is made negligible by employing a circular cylindrical conductor of smaller diameter placed coaxially inside another hollow conductor larger diameter and of certain thickness. Here the inner tube is separated and insulated from the outer conductor by a dielectric medium which may be solid or gaseous. The resulting structure is called:

The electromagnetic wave is guided between the two tubes and the outer conductor acts as a shield to prevent leakage of signal from inside to outside and vice versa. The mode of wave propagation inside the coax is ______.

Which of the following is not a type of coax?

Use copper braided outer conductor, a thin center conductor and a low loss solid or foam polyethylene (PE) dielectric.

Have solid dielectric and use thin outer conductor so that it could be bent for convenience while laying cables

Have solid dielectric made of Teflon (PTFE). The space inside the tubes is essentially air with PTFE separating plugs at regular intervals.

The coax can be used up to for transmitting large signal powers.

Beyond the frequency limit of the transmission of electromagnetic waves along the coax becomes difficult due to losses that occur in the solid dielectric needed to support the conductors, losses in conductors is due to ______.

A transmission line consisting of a suitable shaped hollow conductor which may be filled with a dielectric material and is used to guide the EM waves of UHF propagated along its length.

The loss in a waveguide will be _____ coax.

Inside a waveguide, the TEM mode:

Inside a waveguide, the mode/s:

Which is not an advantage of a waveguide over a coax?

A transmission line where two signal wires are used to propagate electromagnetic waves relative to some fixed potential, usually assumed to be ground.

A transmission line where one conductor forms the signal side, while the other is the ground

A transmission line has the properties of inductance, capacitance, and resistance just as the more conventional circuits have. Usually, however, the constants in conventional circuits are ____ into a single device or component.

Transmission line constants that are spread along the entire length of the transmission line and cannot be distinguished separately.

The amount of inductance, capacitance, and resistance depends on the: 1. length of the line 2. the size of the conducting wires 3. the spacing between the wires 4. the dielectric (air or insulating medium) between the wires

Which of the following is/are transmission line primary constant/s?

When current flows through a wire, magnetic lines of force are set up around the wire. As the current increases and decreases in amplitude, the field around the wire expands and collapses accordingly. The energy produced by the magnetic lines of force collapsing into wire tends keep the current flowing in the same direction. This represents:

Line resistance is expressed as:

Line inductance is expressed as:

Line capacitance is expressed as:

Which of the following are the transmission line secondary constants?

If the line is infinitely long then the ratio V/I will always produce a constant impedance referred as:

It is the measure of the signal in terms of line attenuation per unit length and phase shift per unit length.

Data compression algorithm that does not preserve information, (i.e the signal is not perfectly reconstructed after decompression)

Which of the following is a LOSSY compression algorithm:

Which of the following is a LOSSLESS compression algorithm:

An entropy encoding algorithm used for lossless data compression that uses a variable length code table for encoding a source symbol.

The ______ technique assigns shorter codes to symbols that occur more frequently and longer codes to those that occur less frequency.

It is probably the simplest method of compression. It can be used to compress data made of any combination of symbols. It does not need to know the frequency of occurrence of symbols and can be very efficient if data is represented as 0s and 1s.

The general idea behind this method is to replace consecutive repeating occurrences of a symbol by one occurrence of the symbol followed by the number of occurrences.

In this compression, the idea is to create a dictionary of strings used during the communication session. If both the sender and the receiver have a copy of the dictionary, then previously-encountered strings can be substituted by their index in the dictionary to reduce the amount of information transmitted.

The most common and most recognized domain suffix is:

What adjustment is to be done with wavelength or aperture to have constant gain?

Indicate which of the following reasons for using a counterpoise with antennas is false:

Indicate which one of the following reasons for the use of a ground screen with antennas is false:

The amount of incident wave energy reflected from a given surface depends on the nature of the surface and the angle at which the wave strikes the surface. As the angle of incidence increases, the amount of wave energy ______ increases

The reflected energy is the greatest when the wave is nearly to the reflecting surface.

When the incident wave is perpendicular to the surface, more of the energy is _______ into the substance

At any incident angle, a mirror reflects _______ of the wave energy.

At any incident angle, a dull, black surface reflects _____.

When the incident wave is perpendicular to the surface, less energy is ______.

Digital modulation schemes for transmitting sampled and quantized values of an analog message signal.

The encoder takes a block of k information bits from the source encoder and adds r error control bits, where r is dependent on k and error control capabilities desired.

In traffic engineering, the average duration of occupancy of a traffic path by a call.

Number of calls receiving at an exchange maybe destined to its own exchange or remoted exchange or a foreign exchange

The statistical properties of the switching systems are a function of the behavior of users who encounter call blocking

Continuous 60 minutes interval for which the traffic volume or the number of call attempts is greatest.

It is the busy hour each day varies from day to day, over a number of days.

The 1 hour period starting at the same time each day for which the average traffic volume or the number of call attempts is greatest over the days under consideration.

Based on the status of the called subscriber or the design of the switching system the call attempted may be successful or not.

It is an important parameter in deciding the processing capacity of an exchange

It is a useful parameter in designing a local office to handle the peak hour. It is the average number of calls originated by a subscriber during the busy hour.

Defined as the ratio of busy hour calling rate to the average calling rate for that day.

If, for a signal s(t), the energy of the signal is finite, the signal is called:

A signal that have a finite power but may have finite or infinite energy.

Assuming the independent variable „t' to represent time, if s(t) is defined for all possible values of t between its interval of definition (or existence), T1≤ t ≤ T2. Then the signal s(t) is:.

Noise voltage/current generated by a resistor. Such signals are labeled as:

If a signal s(t) is defined only for certain values of t over an interval T1st

If s(t) = s(t + T), for entire range of t over which the signal s(t) is defined and T is a constant, s(t) is said to be periodic or repetitive. „T‟ indicates the period of the signal and 1/T is its frequency of repetition.

If the magnitudes of a real signal s(t) over its range of definition, T1< t< T2, are real numbers (there are infinite such values) within a finite range, say, Smin ≤ S(t) ≤ Smax, the signal is:

Electrons move to E-fields.

Strongest radiation from accelerating electrons linearly:

The orientation of the E-field determines the polarization of the wave because

Antennas transmit & receive radio waves

The ________ shows how antennas distribute energy in space.

In antenna's, its‟s a place where power is applied:

Angle between the two points at which power is 1/2 that at the peak (-3 dB points)

The ______ measures re-distribution of energy of an antenna.

A 3-element Yagi may have up to _______ gain.

Oldest and simplest form of antenna:

In a dipole, current is maximum at:

In a dipole, voltage is maximum at:

In a dipole, voltage is minimum at:

For antenna elements, thicker conductors are ________ electrically.

In antennas, radiated energy is strongest _______ to an electron‟s motion.

Electrons move ______ the length of a dipole.

Radiation is strongest _______ to the dipole

_________ is a “bent” dipole.

Radiation pattern of an inverted vee antenna adds the effect of ground gain from reflections. It can add as much as _____ over free space.

Ground gain of inverted vee varies with:

In the broad side of a ground plane antenna:

In the axis of a ground plane antenna:

A ________ signal is composed of two sinusoidal carriers, each having the same frequency but differing in phase by one quarter of a cycle.

An encoding scheme that is specified in IEEE 802.3ab for use with 1000BASE-T, which uses all four cable pairs for simultaneous transmission in both directions. Each group of eight bits is converted to one transmission of four quinary symbols across four balanced twisted-pairs. Each symbol represents two binary bits.

It is a term used to describe the transmission of signals in one direction only. A simple, but familiar, example of this transmission is a public address system without two way speakers. The signal, which represents the speaker‟s voice, is carried to a number of loudspeakers. There is no path for listeners to respond.

A term used to describe the transmission of signals in either direction, but only in one direction at a time.

________ is a term used to describe the transmission of signals in both directions at the same time.

The ratio of the capacitance of an insulated conductor to the capacitance of the same conductor uninsulated in the air.

The insulation‟s ability to resist the flow of current through it. For inside conductors, it is typically expressed in megohmxkilometer or megohmx1000 feet.

The relative power loss in the insulation is due to molecular excitement and subsequent kinetic and thermal energy losses.

Measures the maximum voltage that an insulation can withstand without breakdown.

Both mutual inductance and capacitance unbalance are affected by the relative length and uniformity of ________.

To minimize crosstalk within a multipair cable, each pair is given a different _____ within a standard range.

For twisted pair cable, tend to preserve their shape better in a cable.

_______ were introduced as a cost-effective multimode transmitter for Gigabit Ethernet and Fibre Channel. They are also used for 10 Gigabit Ethernet and Fibre Channel and will be considered for future data rates such as 40 Gigabit.

_________ is defined as a recurring disturbance advancing through space with or without the use of a physical medium.

It is described as the up and down wave motion that is at right angle (transverse) to the outward motion of the waves.