Microwave Communication Basics

Question 1

Can be ____ when, in digital applications, the signal is demodulated and re-modulated before transmission to the next radio hop.

Answer 1

regenerative

Question 2

For standard refractivity conditions, k = __ =___

Answer 2

1.33 = 4/3

Question 3

Microwave radio provides a transmission medium for digital traffic of standard capacities typically ranging from 1.544 Mbps (1T1) to 45 Mbps (1DS3) in North America, and from 2.048 Mbps (1E1) to 34 Mbps (16E1) based on ITU standards.

Answer 3

Plesiochronous Digital Hierarchy (PDH)

Question 4

Lowering the system gain will reduce the ___.

Answer 4

fade margin

Question 5

The Earth’s radius model is most useful for __.

Answer 5

terrestrial paths

Question 6

Makes it possible to utilize a common antenna for both the transmitter and receiver.

Answer 6

antenna-coupling unit

Question 7

a calculation involving the gain and loss factors associated with the antennas, transmitters, receivers, transmission lines, and propagation environment, used to determine the maximum distance at which a transmitter and receiver can successfully operate.

Answer 7

link budget

Question 8

The higher the frequency, the ____

Answer 8

narrower the Fresnel zone

Question 9

Radio link typical distance can be up to ___.

Answer 9

25 mi (40 km)

Question 10

defined as the factor that is multiplied by the actual Earth radius

Answer 10

effective Earth radius factor (k)

Question 11

amplifies the received signal (which is at this point much weaker than when it was transmitted), filters out any undesirable signals (interfering signals)

Answer 11

receiver

Question 12

can be described as any criterion to ensure sufficient antenna heights so that, in the worst case of refraction (for which k is minimum), the receiver antenna is not placed in the diffraction region.

Answer 12

Clearance

Question 13

Radio stations between two terminal stations are called ___.

Answer 13

Repeater stations (active or passive)

Question 14

lower k-values will lower the ___

Answer 14

LOS

Question 15

The purpose of _____ to generate the carrier frequency that is to be used for the communication, to modulate this carrier frequency with the desired information, and finally, to amplify the signal

Answer 15

transmitter

Question 16

microwave radios are typically used for high-capacity backbone systems.

Answer 16

Synchronous Digital Hierarchy (SDH) / Synchronous Optical Network (SONET)

Question 17

Transmitted information can be ____.

Answer 17

Voice
data
video

Question 18

to interconnect the antenna with the transmitter/receiver

Answer 18

transmission lines

Question 19

antenna must have clearance of ___ percent or greater at k=4/3

Answer 19

100

Question 20

Made by a number of intermediate repeaters with or without partial payload drop-insert.

Answer 20

Single connection links

Question 21

Combination of these three components is called ____.

Answer 21

Radio terminal

Question 22

A functionality provided in analog and digital repeaters, where only radio-system specific control and service channels, and possibly part of the payload, are made available for local traffic and system management and maintenance.

Answer 22

Drop-insert

Question 23

the difference between the received signal and receiver threshold value (or sensitivity) for given Bit Error Rate (BER)

Answer 23

fade margin

Question 24

Active repeaters can be ____ when signal is only filtered and amplified.

Answer 24

nonregenerative

Question 25

Using the effective Earth’s radius model, ray paths between transmitters and receivers near the Earth’s surface can be __.

Answer 25

approximated by straight lines over a spherical Earth.

Question 26

defined as the difference between the transmitter output power and the receiver threshold.

Answer 26

System gain

Question 27

antenna must have clearance of ____ percent at the minimum k suggested for the certain path.

Answer 27

60

Question 28

___ the signal level at which the radio runs continuous errors at a specified bit rate.

Answer 28

receiver sensitivity threshold

Question 29

Together, feeder cable losses, antenna-coupling losses, and any additional losses (depending on the radio configuration) constitute ____.

Answer 29

branching losses

Question 30

Radio links may be established between any two points within ___.

Answer 30

Line of sight
frequency
geographical region
rain statistics

Question 31

implemented without any active radio components.

Answer 31

Passive repeaters

Question 32

Three basic components of typical digital microwave radio.

Answer 32

1. Digital modem for interfacing with digital terminal equipment
2. Radio Frequency (RF) unit for converting a carrier signal from the modem to a microwave signal.
3. Antenna used to transmit and receive the signal.

Question 33

___ adapts the generated signal to the surrounding environment (to the propagation medium) and directs the radio waves that are to be transmitted towards the receiving station.

Answer 33

antenna

Question 34

Sent using a highly directive parabolic shaped antenna

Answer 34

Microwave

Question 35

The mean Earth radius is in average __.

Answer 35

6, 371 km