2B Communications

a. A & B

On which factors of earth does the magnitude of tilt angle depend in surface wave? A. Permittivity B. Conductivity C. Resistivity D. Reflectivity a. A & B b. C & D c. A & C d. B & D

Spherical/Circular

Isotropic radiation pattern

a. D-region

Which ionization layer exists during day time & usually vanishes at night due to highest recombination rate? a. D-region b. Normal E-region c. Sporadic E-region d. Appleton region

Isotropic

Study of radiation patterns is simplified if the radiating element is considered

B. Ku

Which frequency band has the smallest antenna size? a. C B. Ku c. None of these d. all of the above

Medium

Velocity of waves depends on the ____

Maximums

Points on the pattern of greatest intensity

Phase

Comparing the face of the electric field at two or more points within the pattern

Power

NOT a fundamental properties of electromagnetic radiation

Low Frequency

Used for long distance telegraphy navigation such as Omega

5 MHz

Critical frequency of F1 layer

Major Lobes

Lobes of a pattern having the greatest intensity

Critical frequency

Highest frequency that will be returned down to earth

A. Delayed spreading

In microwave transmission using digital radio, what causes most intersymbol interference? A. Delayed spreading B. Rayleigh fading C. Random Doppler shift D. Slow fading

c) polarization diversity

A type of diversity where a single RF carrier is propagated with two different electromagnetic polarization a) space diversity b) wavelength diversity c) polarization diversity d) hybrid diversity

c. Back lobe

In a non-isotropic directional antenna, which radiating lobe axis makes an angle of 180° w.r.t. major beam of an antenna? a. Minor lobe b. Side lobe c. Back lobe d. None of the above

B. Space diversity

Is a method of diversity reception applied to reflective path to reduce fading A. Frequency diversity B. Space diversity C. Polarization diversity D. Wavelength diversity

Refraction

Bending from high electron density to regions of lower electron density

8 Hr

If TX height = RX height, what is the max distance between 2 towers for LOS communications

D. Large reflector

Which causes multipath or frequency selective fading? A. Small reflector B. Nearer reflector C. Further reflector D. Large reflector

d. Combiner

A component that combines microwave signals from separate transmission lines into one common transmission line and allows no coupling between the separate lines a. Isolator b. Circulator c. Directional coupler d. Combiner

-150 deg

If electric current is at -30 deg, where is the electric voltage after half wavelength?

C) footprint

The signal from a satellite is normally aimed at a specific area called the _________ A) path B) effect C) footprint D) none of the above

B. Frequency diversity

A method of diversity reception where the signal is transmitted on two difference frequencies over the same path A. Space diversity B. Frequency diversity C. Polarization diversity D. Wavelength diversity

The standby indicator (red) is lit

Not displayed when radio is on Standby mode

a. A & B

Which among the following elucidate the generation of electromagnetic waves? A. Ampere’s law B. Faraday’s law C. Gauss’s law D. Kirchoff’s law a. A & B b. B & C c. A & C d. B & D

Antenna Gain

Increases ground wave coverage

D. Cardoid or Limacon

The radiation pattern of loop antenna is A. Circle B. Semicircle C. Elliptical D. Cardoid or Limacon

Vertical

A polarization that electric phasor is perpendicular to the reflecting plane

Lobes

Portions on the pattern between adjacent nulls

c. both a and b

What two types of band are used in VSAT? a. Ku b. Ka c. both a and b d. none of the above

d. All of the above

What can affect the signal transmission? a. curvature of the earth b. roughness of the earth c. Magnetic field of earth d. All of the above

b. 10 GHz

Rainfall is an important factor for fading of radio waves at frequencies above a. 1 GHz b. 10 GHz c. 100 GHz d. 100 MHz

Shape

Description of pattern generally includes the locations of maximums and nulls

Radiation Pattern

Plot of electric field iPlotted in terms of relative field intensity, the interest in primarily the shape of the pattern at a fixed distance, as a function or direction from the antenna or antenna array

Minor Lobes

Lobes of a pattern having smaller maximum values

Skip distance

Shortest distance from a TX measured along the surface of the earth

c. Radiated

Power density is basically termed as power per unit area a. Reflected b. Refracted c. Radiated d. Diffracted

a. Phase

Wavefront is basically a locus of points acquiring similar a. Phase b. Frequency c. Amplitude d. Wave equation

b. Automatic repeat request

ARQ stands for _______ a. Automatic repeat quantization b. Automatic repeat request c. Automatic retransmission request d. Acknowledge repeat request

Wireless Communications

VSAT technology uses?

EHF

Spectrum for high rate digital links, satellite, radar and navigation

Sky wave propagation

Used for long distance communication at 3-30 MHz

Induction field

Contains only reactive energy since electric and magnetic fields are 90 deg out of time phase. Of importance only in the immediate vicinity of the antenna

b. Away

According to Snell’s law in optics, if a ray travels from dense media to rarer media, what would be its direction w.r.t the normal? a. Towards b. Away c. Across d. Beside

a. A & C

How is the effect of selective fading reduced? A. By high carrier reception B. By low carrier reception C. By single side band system D. By double side band system a. A & C b. B & D c. A & D d. B & C

White cross on a red background

MARC fault

b. Spherical to plane wave

Which conversion mechanism is performed by parabolic reflector antenna? a. Plane to spherical wave b. Spherical to plane wave c. Both a and b d. None of the above

Virtual Height

If the ______ is known, it is simple to calculate the angle of incidence required for the wave to return to ground

d. slow fading

What do you call an attenuation that occurs over many different wavelengths of the carrier? a. rayleigh fading b. rician fading c. wavelength fading d. slow fading

Ground waves

A type of propagation that includes all of the components of radio wave except those affected by the ionosphere

Minimums

Field intensity at these points have values greater than zero

90-150 mi

F1 height

SHF

3-30 GHz

377 ohms

Impedance of free space

Radio waves

A form of electromagnetic radiation

b) quad diversity

The combination of the frequency, space, polarization and receiver diversity into one system a) hybrid diversity b) quad diversity c) space diversity d) wavelength diversity

a. Ionospheric reflection

High-frequency long-distance propagation mostly depends on a. Ionospheric reflection b. Tropospheric reflection d. Ground reflection e. Inverted reflection

Radiation field

Consists of the lines of force which have become detached from the antenna and are moving out into space as an electromagnetic wave. Electric and magnetic fields are in time phase

D. Circulator

What ferrite device can be used instead of duplexer of isolate microwave transmitter and receiver when both are connected to the same antenna? A. Isolator B. Magnetron C. Simplex D. Circulator

"that a changing magnetic field will produce an electric field and that a changing electric field will produce a magnetic field"

Maxwell's equation

Pattern

Plotted in terms of relative field intensity, the interest in primarily the shape of the pattern

B. Ku

Which frequency band should be used for smaller VSAT? a. C B. Ku c. None of these d. all of the above

a) 24 hours

A synchronous satellite orbits the earth once in a) 24 hours b) 12 hours c) 6 hours d) 1 hours

d. slow fading

Which of the reception problems below is not due to multipath? a. delayed spreading b. rayleigh fading c. random doppler shift d. slow fading

D. All of the above

The total noise of a satellite earth station receiving system consists of A. Sky noise B. Antenna and feeder noise C. Parametric amplifier noise D. All of the above

b) Communication satellites

The satellite that is used as a relay to extend communication distance is called as _____ a) Relay satellites b) Communication satellites c) Repeater satellites d) Geosynchronous satellites

Nulls

Points on pattern where the relative field strength is zero

D) Fading

The fluctuation in the received signal strength at the receiver or a random variation in the received signal is known as A) Absorption B) Cycling C) Fluctuation D) Fading

either a or b ang itry, kasi mali na daw ang c and d (2893.31 or 2523.83)

What is the effective radiated power (ERP) of repeater with 450 W transmitting power output, 4 dB feedline loss, 6dB duplexer loss, 7 dB circular loss and feedline antenna gain of 25 dB? a. 2893.31W b. 2523.83W c. 2839.31W d. 2425.38W

B. Frequency diversity

The best system configuration to overcome multipath fading of microwave system over the water A. Space diversity B. Frequency diversity C. Polarization diversity D. Wavelength diversity

Interference

Occurs when 2 waves that left 1 source and travelled by different path arrive at a point after being reflected from ground

Space waves

Propagation used beyond 30 MHz

Polarization

Determined by the position of the electric field with respect to the reflecting surface

Wavefronts

Energy leaves transmitting antenna in the form of _____

C. earth station transmitter

Primary component of uplink section of satellite is A. transformer B. transistor C. earth station transmitter D. power station transmitter

c. Mid

Dipole antenna is symmetrical in nature where the two ends are at equal potentials with respect to ____ point a. Initial b. Eventual c. Mid d. None of the above

c. S/N to AG

Shannon law is a. frequency to AG b. P to AG c. S/N to AG

Spherical

Propagation pattern of isotropic antenna

A. Isolator

Which of the following permits a microwave signal to travel in one direction with virtually no loss, but severely attenuates any signal attempting to travel in the reverse direction? A. Isolator B. Wave trap C. Tunnel diode D. Circulator

Uplink: 1.6 - 1.7

Downlink: 1.5 - 1.6

L-band (GHz)

Uplink: 2.5 - 2.7

Downlink: 2.1 - 2.3

S-band (GHz)

Uplink: 5.925 - 6.425

Downlink: 3.7 - 4.2

C-band (GHz)

Uplink: 14 - 14.5

Downlink: 11.7 - 12.2

Ku-band (GHz)

Uplink: 27.5 - 31

Downlink: 17.7 - 21.2

Ka-band (GHz)

Satellite Access Control

SAC

48 user bytes (sya lang may user bytes)

How many user Bytes in 53 Bytes?

2?

How many NMS in HUB

56 Kbps up to 4 Mbps

vsat data rate

135mbps

Outbound per ns data rate

3,700-4,200Mhz

5,925-6,425 MHz

C downlink and uplink

14.0-14.5 GHz

11.7-12.2 GHz

Ku uplink and downlink

27.5-31.0 GHz

17.7-21.2 GHz

Ka uplink and downlink

BUC

nag up convert ng freq

LNB

nag down convert ng freq

Inbound

from vsat to hub

Outbound

from hub to vsat

Ksps × (1+roll off factor)

formula of bandwidth

symbol rate and arrangement of Modcod

what is carrier type

360 ms

superframe