Wirelesses Technology

If two resistors are wired in series the voltage across them are equal and opposite until?

a shift occurs in the input signal frequency

Load impedance is equal to the characteristic impedance the input impedance is equal to this

characteristic impedance

A build up until the voltage of the capacitor is equal to the voltage of the battery source and opposite in polarity

electric field

This normally determines the electromagnetic waves plane of polarization?

the plane in which the electric field or E field propagates with respect to the Earth

These weather conditions can enable UHF TV transmission to be propagated far beyond normal radio Horizons distances?

A transmitting antenna extends into a temperature inversion

Changing the angle of the radius during and between cycles modifies the _______________ of the carrier wave?

Amplitude

This happens when you change the speed that the radius completes its cycle, or _____________ varies the length of the sine waves within a carrier.

Frequency

What are the three categories of transmission line loss?

Ohmic losses, sometimes called copper losses, dielectric losses and radiation losses

Outputs of the two AM modulators that are multiplexed into one signal and four bits of data or more are transported simultaneously in the same clock cycle?

QAM (quadrative amplitude modulation)

What is the active bandwidth of the FM radio station in North America?

-75 kilohertz to positive 75 kHz

At what frequency does the electromagnetic frequency spectrum begin?

3000 Hz

How are standing waves on a transmission line formed?

By forward and reflected waves that pass each other as they travel in opposite directions along the line, Vector sum of the forward and reflected waves change in the amplitude and phase yet their positions remain stationary

This rule is the most significant factor in determining the bandwidth of a narrow band frequency modulation carrier

Carson's rule

What is the main characteristic of a frequency modulation waveform?

FM waveform deviates in proportion to the modulation sine wave while the amplitude remains constant

Waves that travel in the same direction as the disturbance, sound waves are the most common type?

Longitudinal waves

Occurs around a conductor when current flows through it or when any moving electrical charge passes through the conductor?

Magnetic field properties

In an AM waveform envelope, for a modulation index of 0.5, is the modulation signal the same amplitude as the carrier?

No, for a modulation index of 1.0, the modulation signal is the same amplitude as the carrier

_____________ refers to the difference in timing between two sine waves of the same frequency

Phase

The output of the two mixers are multiplexed into one signal and two bits of data are transported simultaneously in the same clock cycle?

QPSK (quadrature phase-shift keying)

What distinguishes quadrature phase-shift keying from quadrature amplitude modulation?

QPSK only uses phase modulation, QAM combines phase and amplitude modulation to provide higher data throughput

What is the term used to designate the entire range of electromagnetic waves arranged in order of their frequencies?

Spectrum

Upon what principle do frequency modulation demodulator detector circuit designs operate?

Voltage being created when the signal frequency moves from the center frequency

What causes the condition known as resonance?

a capacitor and inductor have the same magnitude of reactance causing energy to move back and forth between the inductor and capacitor

In a hybrid fiber coax network, a corroded connector or seizure screw forms what? that acts as an envelope detector.

a crude diode

This uses vibrations that propagate across the surface of a crystal to an output transducer, where the vibrations are converted back to electrical energy

a saw filter

What causes a traveling wave pattern through transmission lines?

a signal source applied to a transmission line that terminates into a load with a matching characteristic impedance

What direction does the radio wave refraction always go?

always toward the medium that causes the lower velocity of the wave front

Where is an electric field located with respect to the charged conductor?

an electric field is at a right angle to the conductor

What characterizes a narrow band frequency modulation carrier?

by modulation index of less than one modulation frequencies that range from 300 to 3000 Hz and frequency deviation that ranges from 10 to 30 kHz

How does a transmission lines and input impedance differ from its characteristic impedance?

characteristic impedance is a function of the inductive and capacitive properties of the line whereas the transmission line input impedance is a function of the transmission line length

Stores energy in the form of an electric field which is at the right angles to the conductors

charged capacitor

What is a property of inductor/capacitor filter circuits that occurs near their cut-off frequency?

components take longer to get through the filter creating what is called a group delay

What are the three measurable elements of a sine wave?

cycle, cycle length or wavelength, and amplitude

What stage of the RF receiver recovers the signal that was modulated onto the carrier at the transmitter?

demodulator stage or also called the detector stage

How many side bands of significant amplitude are created by the frequency modulation process?

dependent on the FM modulation index

Where is the automatic gain control voltage that maintains the intermediate frequency amplifier gain at the appropriate level developed?

detector or the demodulator section

What part of the coaxial cable is the TEM wave primarily in?

dielectric

A radio wave is not blocked that meets an obstacle it has a natural tendency to bend around the obstacle or this?

diffract

This gives greater range for the same transmitted power or allows lower power transmission, preserving the battery in portable radios

double sideband suppressed carrier

What are the two main components of an electromagnetic wave?

electric and magnetic field

What determines the electrical length of a transmission line?

electrical length is dependent on the wavelength of the signal or signals being transported

Movement of the magnet inside a coiled wire momentarily breaks the magnets magnetic field and induces a current into the coil. The polarity of the current changes when the magnet is moved in and out of the coil.

electromagnetic wave

Caused by a number of issues but two of the more common ones are changes in the waves polarization and the reception of waves traveling over different paths or multipath

fading

Most suitable for digital signals

finite impulse response filter

A results from the radio wavefront spreading out as it travels away from the transmitter much like the beam of a flashlight

free space loss

This distinguishes radio waves from other electromagnetic waves?

frequency spectrum

This is often overlooked when connecting a coaxial cable to a transmitter or receiver?

ground connection

A loss that occurs when radio waves are propagated via multi-hop refraction, causing RF energy to be lost each time the radio wave is reflected from the Earth's surface?

ground reflection loss

A type of wave that is composed of two surfaces, surface wave and space wave

ground waves

A type of polarization that occurs if the E field propagates in a plane parallel to the Earth's surface

horizontal polarization

In a standing wave, where are the amplitudes the highest?

in the Anti-nodes

Where is the AGC voltage developed?

in the demodulator part of the receiver

What prevents the circuit following the tuner stage from being driven into overload by additional signals?

input filter

What are the 4 most common LC filter types?

low pass filter, high pass filter, bandpass filter and band stop filter

This field occurs around a conductor when current flows through it or when any moving electrical charge passes through the conductor

magnetic field

Caused by a disturbance or vibration in a medium such as Gas, Liquids, solids, or plasma.

mechanical wave

Why is the modulation information generally called baseband information or a baseband single?

modulation information is usually in its basic need of electrical format

A transmission line where the characteristic impedance of the line is the same as the impedance of the load

non-resonant transmission line

Why must modulation of a wave's phase be relative to a reference phase?

phase dimension of a carrier wave is at an angle, to convey information, modification of the phase must be relative to a reference phase

How many data bits are in each symbol at the output of a quadrature phase-shift keying modulator?

plotted on a polar coordinate graph, each quadrant contains one symbol with two data bits.

Smooth surfaces influence radio waves to do this off of the Earth's surface?

reflect

An abrupt change in velocity influences radio waves to do this off of the Earth's surface?

refract

This transmission line designation is defined as a line in which the characteristic impedance of the line and the load are different?

resonant transmission line

Tuning elements are unnecessary for maximum power transfer in this type of transmission line

resonant transmission line

This transmission line is virtually without any electrical properties and is a non-factor in the system's operation

short transmission lines

Used in marine, aviation, military, and amateur radio applications for long-range voice Communications

single side band

A type of wave that is composed in the ionosphere which is the region of the atmosphere that extends from about 31.1 Mi or 50 km above the surface of the Earth to about 250 miles or 402 km above the surface

sky waves

This enables skywaves to be propagated at great distances?

skywaves are radiated in an upward direction, they strike the region of increased ionization causing their velocity to increase and then refract back towards Earth

Separate components of a ground wave are called?

surface wave and space wave

When demodulating an AM wave form, High Distortion in insensitivity to low signals can be overcome with what?

synchronous detection

What is a characteristic of the filters in the intermediate frequency section of receiver?

the IF filter is either very flat on the top, the passband or has some desired shape and the sides or skirts of the IF filter are usually very sharp or steep

What happens to the current incident wave when it encounters an open terminated transmission line?

the current is unable to exit the line while additional current continues to arrive rather than building a charge or disappearing, the laws of physics requires that an equal and opposite current flows back towards the source

What are the distributed elements in a coaxial cable transmission line?

the diameter of the center conductor and inside surface of the shield provide resistive and inductive elements, the separation between the conductors provide the capacitive element and the dielectric constant of the material separating the conductors determines the conductive element

What is the phase relationship between the electric and magnetic fields?

the electric and magnetic fields are displaced 90° apart in phase

What does the modulation index in amplitude modulation express?

the ratio of the modulating signal level to the unmodulated carrier

In the circular reference with the right triangle, what represents the amplitude or power in the sine wave?

the triangles vertical line length changing while the radius length remains constant during a full cycle

Why are class A amplifier used in Broadband cable applications?

to minimize distortions in the mixing of multiple RF input signals

The motion of the wave that travels at a right angle to the direction of the mediums disturbance

transverse wave

What type of wave motion is used for radio communications?

transverse wave motion

What type of wave motion is used for radio communications?

transverse waves

What are the layers of the Earth's atmosphere?

troposphere, stratosphere and the ionosphere

Even though it may be omitted from a block diagram of a receiver, why should the power supply be the first thing that is checked when troubleshooting a bulky circuit?

troubleshooting an improperly powered circuit is futile

The area where the receiver takes the antenna signal, filters it, amplifies it, then converts it to an intermediate frequency.

tuner

This is the earliest form of transmission line used for electrical power distribution, Telegraph, and early telephone Communicationsy

two wire open-air transmission line

Also known as twin lead this may be connected to the folded dipole element of a TV antenna, one of the most common applications

two wire ribbon transmission line

These characteristics are common to all two types of to wire transmission lines?

two wire transmission lines operate as a balanced line or balanced signal pair, consisting of two conductors of the same length and type and each conductor has the same impedance along its length as well as to ground

What is the most notable characteristic of coaxial cable transmission lines?

unbalanced line with a single signal conductor surrounded by a dielectric insulating material

A type of polarization that occurs if the E field component of a radiated wavefront travels in a plane perpendicular to the Earth's surface

vertical polarization

An antenna that is likely to be used in mobile or vehicular comunications also called an omnidirectional antenna

vertically polarized antenna

This is produced by using filters to eliminate most of the sideband so that only a "vestige" of the side band remains.

vestigial sideband

What type of amplitude modulation is used for analog television transmission?

vestigial sideband to conserve bandwidth

This type of amplifier is used as an output amplifier

what is Class B

This amplifier has an output that is very high and harmoniCs that must be attenuated by filter Network

what is Class C

This type of amplifier approaches but never achieves 100% efficiency

what is Class D

What is done in set-top boxes to strike a balance between image rejection, and bandwidth of the intermediate frequency filter, and the frequency at which demodulation is done.

what is a double IF conversion

A line length of exactly one half wavelength, the input impedance is equal to this?

what is load impedance

The line length is considerably shorter than the wavelength the input impedance is equal to this?

what is load impedance

What time of day is radiation the greatest in the ionosphere?

what is noon

How is a magnetic field around a conductor created?

when current flows through it and when any moving electrical charge passes through the conductor

What class of an amplifier conducts current during the entire input waveform and is inherently lineAr?

Class A amplifiers