Microwaves

Microwaves

electromagnetic waves with frequencies ranging from 300 MHz to 300 GHz

ITU

responsible for controlling the allocation of spectrum

ITU-T

handles standards for end-to-end circuits covering all media

ITU-R

deals with radio link

microwave link

a high frequency radio link designed to provide a signal connection between two points

hop

Two microwave terminals form a ___

Microwave Radio

a point-to-point fixed digital link that operates in duplex mode

Duplex Mode

means that each channel consists of a pair of frequencies for transmission and reception

Microwave Radio

Sometimes called low-band channels and high-band channels

T to R spacing

Spacing between two frequencies

Frequency Division Duplexer

The transmit and receive frequencies are combine in a single antenna using ____

duplexer

provides coupling for the two signals

Digital modem

to interface with the customer equipment and convert customer traffic to a modulated signal

RF unit

to up and down convert signal in RF range

Passive Parabolic Antenna

transmission and reception of signals

E1

the basic digital channel containing 30 voice channels and 2 other channels (for sync and signaling) at 64 kbps each and time division multiplexed

E1

has a total bit rate of 2.038 Mbp

1 + 0 configuration

non-protected

1 + 1 configuration

protected and Monitored Hot Standby (MHSB)

Short Haul

uses frequencies greater than 15 GHz

Long haul

uses lower frequencies to minimize attenuation

Narrowband

generally less than 3 GHz in frequency

Wideband

utilizes frequencies from 3 GHz to 15 GHz

Microwave links

used for the control and maintenance of the power grid

Microwave links

used to connect radio/TV repeaters to main and regional transmission sites

Microwave links

used for BTS-BTS, BTS-BSC, BSC-MSCMSC-PSTN connections

k-factor

designed as the ratio of the effective radius to the actual radius of the earth. Used to determine the relative clearance and not to predict the beam curvature.

k-factor

a numerical figure that considers the non-ideal condition of the atmospheric refraction that causes the beam to be bent toward to, or away from the earth

Standard Refraction

When the gradient of refractivity displays average characteristics

super refraction

results from meteorological conditions such as temperature inversion or marked decrease in total moisture content of the air

Substandard Refraction

this occurs when the dielectric constant of the atmosphere increases with weight.

inverse beam bending or earth bulging

The microwave beam tends to be deflected away from the earth

temperature inversion and negative humidity gradient or hydrolapse

Negative refractivity gradient results from

Evaporation

may lead to ducting

Advection

also leads to duct formation

Temperature inversion

the primary cause of ducts which influence radio link propagation

blackout

When G becomes negative, ____ conditions may occur

Ground-based Duct

a very dense layer of air close to the ground with a thin layer on top of it

Elevated duct

exists when the atmosphere has a thick layer in some height above the ground

Ducting Probability

refers to the percentage of the time when dN/dh is less than -100N/km for a specified monthz

Equatorial regions

the most vulnerable to ducts