Digital Radio System

8/16/2019 Digital Radio System

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Digital Transmission System(DTS) Digital Radio Transmission Technology

EETP/BSNL Silver Certification Course Page 1 of 24

For Restricted Circulation

EETP/BSNLSILVER CERTIFICATION

COURSE DIGITAL TRANSMISIION

SYSTEM

VERSION 1 JUNE 2013


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Contents

Sl. No. Name of Topic Page No.

1

INTRODUCTION

3

2 ELECTROMAGNETIC SPECTRUM 4

3 MICROWAVE 5

4 MICROWAVE RADIO RELAY 6

5 HOW MICROWAVE RADIO RELAY LINKS ARE FORMED 7

6 MICROWAVE LINK 8

7 TRANSMISSION CAPACITIES AVAILABLE ON THE RADIO

SYSTEMS

9

8 DIGITAL RADIO APPLICATIONS 11

9 MICROWAVE RADIO COMPONENTS 11

10 TYPICAL MW SYSTEM 14

11 MINILINK 14

12 BROADBAND VSAT 16

13 DIGITAL SATELLITE PHONE TERMINAL (DSPT) 20

14 SUMMARY 22


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4 DIGITAL RADIO TRANSMISSION TECHNOLOGY

STRUCTURE

4 DIGITAL RADIO TRANSMISSION TECHNOLOGY

4.1 INTRODUCTION

4.2 OBJECTIVE

4.3 ELECTROMAGNETIC SPECTRUM

4.4

MICROWAVE

4.5 MICROWAVE RADIO RELAY

4.6 HOW MICROWAVE RADIO RELAY LINKS ARE FORMED

4.7 MICROWAVE LINK

4.8 TRANSMISSION CAPACITIES AVAILABLE ON THE RADIO

SYSTEMS

4.9 MICROWAVE RADIO COMPONENTS

4.10 TYPICAL MW SYSTEM

4.11 MINILINK

4.12 BROADBAND VSAT

4.13 DIGITAL SATELLITE PHONE TERMINAL (DSPT)

4.14 SUMMARY

4.15

SELF ASSESSMENT QUESTIONS

4.16 REFERENCES AND SUGGESTED FURTHER READINGS

4.1 INTRODUCTION

We use the radio portion of the electromagnetic spectrum for many things,

including television and radio broadcasting, telephones and other wireless


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communications, navigation and radar for a variety of measurements including police

speed traps, and even microwave cooking ovens.

MINI-LINK is the world's leading microwave solution, suitable for any

network scenario. It enables flexible and speedy network rollout, and provides gigabit

capacity and carrier-grade availability. MINI-LINK E can be configured to meet any

network requirement for capacity and range. It provides radio transmission links from

2 up to 17x2 Mbit/s, operating within the 7 to 38 GHz frequency bands.

4.2 OBJECTIVE

After reading this unit, you should be able to understand:

Microwave Frequencies

Microwave link Properties

Microwave radio relay

Different Digital radio systems

6 Ghz Digital Microwav

Mini Link

4.3 ELECTROMAGNETIC SPECTRUM

Electromagnetic waves can be broadly classified in terms of frequencies along

with their uses as follows in Table-1:

Table-1

RANGE NAME WAVELENGT

H

USES

0 – 30 KHz V.L.F. Up to 10 km. Used for long communication. Has limited

information. Bandwidth requires very high

power.

30 – 300KHz L.F. 10 km to 1 km

0.3 – 3 MHz M.F. 1 km to 100 m Radio Broadcast, Marine Power in KW,

ground wave propagation, i.e. follows the

curvature of the Earth.

3 – 30 MHz H.F. 100 m to 10 m Long haul point to point communication.

Propagation is by one or more reflections

from ionosphere layers and so subject to


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variations.

30 – 300

MHz

V.H.F. 10 m to 1 m Line of sight, Tropo-scatter communication.

0.3 – 3 GHz U.H.F. 1 m to 10 cm. –––––– do ––––––

3 – 30 GHz S.H.F. 10 cm to 1 cm. Line of sight, terrestrial M/W and Satellite

communication.

30 – 300

GHz

E.H.F. 1 cm to 1 mm. Experimental.

FIG : 1

Typical EM Spectrum

4.4 MICROWAVE

Microwave transmission refers to the technique of transmitting information

over microwave frequencies, using various integrated technologies. The portion of the

microwave spectrum called millimeter wave is highly susceptible to attenuation by

the atmosphere (especially during wet weather). The term SHF corresponds to

"MICROWAVE" Cent metric waves. As a convention frequencies, above 1 GHz and

up to 40 GHz are termed as Microwave. However, most of the m/w systems available

are in the range of 1 to 18 GHz.

4.4.1 PROPERTIES

Suitable over line-of-sight transmission links without obstacles

Provides good bandwidth

Affected by rain, vapor, dust, snow, cloud, mist and fog, heavy

moisture, depending on chosen frequency (see rain fade)


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4.4.2 PHYSICAL DESCRIPTION:

Extremely high frequency narrow beam is focused over a line-of-sight

path between parabolic antennae (“dish”) mounted at substantial height

on relay towers.

The dishes are fixed and rigid and face a specific direction. A series of

relay towers are needed, the distance between them is based on the height

of towers.

4.4.3 TRANSMISSION CHARACTERISTICS:

Can carry both analog and digital signals.

The frequency spectrum used is 1 to 18 GHz

High bandwidth and data rate

Attenuation loss is high and increases through rainfall especially above

10 GHz (wavelength approaching the size of a raindrop or even smaller).

Microwave use is regulated by the federal communications commission

(FCC). Allocations are made in “bands”.

4.4.4 TYPICAL MICROWAVE DISTANCES

Frequency Approx. distance

2-6 GHz 30 miles

10-12 GHz 20 miles

18 GHz 7 miles

23 GHz 5 miles

4.5 MICROWAVE RADIO RELAY

Microwave radio relay is a technology for transmitting digital and analog

signals, such as long-distance telephone calls and the relay of television programs to

transmitters, between two locations on a line of sight radio path. In microwave radio

relay, radio waves are transmitted between the two locations with directional

antennas, forming a fixed radio connection between the two points. Long daisy-

chained series of such links form transcontinental telephone and/or television

communication systems.


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Fig : 2 How M/W System Works?

4.6 HOW MICROWAVE RADIO RELAY LINKS ARE

FORMED

Microwave transmission involves the sending and receiving of microwave

signals over a microwave link. This microwave link is made up of a string of

microwave radio antennas located at the top of towers at various microwave sites.

Because a line of sight radio link is made, the radio frequencies used occupy

only a narrow path between stations (with the exception of a certain radius of each

station). Antennas used must have a high directive effect; these antennas are installed

in elevated locations such as large radio towers in order to be able to transmit across

long distances. Typical types of antenna used in radio relay link installations are

parabolic reflectors and horn radiators, which have a diameter of up to 4 meters.

Highly directive antennas permit an economical use of the available frequency

spectrum, despite long transmission distances.


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Fig.1 A Typical Microwave Link

4.7 MICROWAVE LINK

A microwave link is a communications system that uses a beam of radio

waves in the microwave frequency range to transmit video, audio, or data betweentwo locations, which can be from just a few feet or meters to several miles or

kilometers apart. Microwave links are commonly used by television broadcasters to

transmit programmes across a country, for instance, or from an outside broadcast back

to a studio.

4.7.1 PROPERTIES OF MICROWAVE LINKS

Involve line of sight (LOS) communication technology

Affected greatly by environmental constraints, including rain fade

Have limited penetration capabilities

Sensitive to high pollen count

Signals can be degraded during Solar proton event

4.7.2 USES OF MICROWAVE LINKS

In communications between satellites and base stations

As backbone carriers for cellular systems

In short range indoor communications

4.7.3 APPLICATIONS: M/W FREQUENCY BANDS ARE USED FOR

THE FOLLOWING SERVICES :

Fixed Radio Communication Services.

Fixed Satellite Services (VSAT & DSPT)


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Mobile Services.

Broadcasting Services.

Emergency Radio Services.

Meteorological Services.

Backhauling of BTS

To meet the requirements of all above mentioned services, co – ordination

among the users of M/W spectrum is necessary. In this regard (in the national context)

the wireless planning and co – ordination wing (WPC) of the ministry of

communication has allotted m/w frequencies spectrum, on the basis of various

wireless users classified as general users and major users. Wireless users who are

permitted to plan their services and take action for the development of the required

equipments are major users. BSNL has been nominated as a major wireless user bythe WPC in 1981 in the following sub base band of the m/w spectrum for fixed radio

communication. Microwave Spectrum Available for BSNL is shown in Table-2.

Table-2

Band Spectrum Space Bandwidth Available

2 GHz 2000 – 2300 MHz 300 MHz

4 GHz 3300 – 4200 MHz 900 MHz

6 GHz 5925 – 7110 MHz 1185 MHz

7 GHz 7425 – 7725 MHz 300 MHz

11 GHz 10,700 – 11,700 MHz 1000 MHz

13 GHz 12,750 – 13,250 MHz 500 MHz

In India the first M/w System was completed in December, 1965 between

Kolkata and Asansol with a system capacity of 1200 channels. At present many

kilometers of M/W systems are scattered throughout the country and further

expansion is taking place at a very large rate.

4.8 TRANSMISSION CAPACITIES AVAILABLE ON THE

RADIO SYSTEMS

The transmission capacities available on digital radio systems are, of course,

integral multiples of PCM hierarchical bit rates and are classified into small, medium

and large or high capacity systems. Specifically this categorization covers:


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Low capacity – 704 kbps, 2 mbps and 8 mbps

Medium capacity – 34 mbps

High capacity – 140 mbps

Some manufacturers and some administrations have used some other integral

multiples also such as 2 x 8 and 2 x 34 mbps systems but these are not being

considered in the Indian network. The 704 kbps system is not other wise a standard

system but has been proposed in the Indian network context, because for the rural

network it is found that a 2 mbps system corresponding to 30 channels was too large

and wasteful of frequency resource. This 704 kbps system corresponds to capacity of

10 channels, which is quite adequate in the rural network of the country.

4.8.1 FREQUENCY BANDS

The frequency bands and the capacities which are proposed to be used bydigital microwave and UHF systems in the country are given in Table-4:

Table-4

NomenclatureBit rate

Mb/s.

No. of

channelsFrequency band

Typical

Applications

Small capacity

0.704 10 658 – 712 MHz (UHF) Rural

Communication,

Hilly terrain

Areas.

2.048 30 400 MHz band (UHF)

8.448 120520 – 585 MHz (UHF)

622 – 712 MHz (UHF)

8.448 1202 GHz band (M/W)

(2.0 – 2.3 GHz)

Medium capacity

34.368 4807 GHz band (M/W)

(7.425 – 7.725 GHz)

As Junction Line

for connecting

exchanges within acity.

34.368 480

13 GHz band (M/W)

(12.75 – 13.25 GHz)

band M/W

34.368 480 15 GHz band (M/W)


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(14.75 – 15.75 GHz)

High capacity

139.264 1920

4 GHz band (M/W)

(3.3 – 3.8 and 3.8 – 4.2

GHz)

Long Distance

connectivity or as

trunk lines for

National

connectivity.

139.264 1920

6 GHz band (M/W)

(5.925 – 6.425 GHz;

Lower)

(6.430 – 7.110 GHz;

Upper)

139.264 1920

11 GHz band (M/W)

(10.7 – 11.7 GHz)

4.9 MICROWAVE RADIO COMPONENTS

4.9.1 WAVEGUIDES Conventional transmission lines develop too much loss at microwave

frequencies.

Hollow waveguides present an alternative.

Electromagnetic waves reflect from the walls of the wave guide as it travels its

length.

Brass, aluminum or silver plated. Rectangular, elliptical and circular.


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Fig : 3 Different types of Waveguide

4.9.2 BENDS AND TEES BENDS: if the transition through the bend is gradual there will be a

minimal effect.

Fig : 4 Bends

TEES:

o E plane tee output is out of phase with the input. (series tee).

o H plane tee is in phase with the input. (shunt tee)


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Fig : 5 Tees

4.9.3 ANTENNA The antenna is the “air interface” of a communication system

An antenna is an electrical conductor or system of conductors that

performs; Transmission - radiates electromagnetic energy into space

Reception - collects electromagnetic energy from space

In two-way communication, the same antenna can be used for

transmission and reception with the use of suitable receiver protection

The principle of reciprocity states that the transmit and receivecharacteristics of an antenna are identical

Size of an antenna depends primarily on the frequency that it is designed

to transmit or receive

Fig : 6 Typical MW Antennas


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4.10 TYPICAL MW SYSTEM

Wide band M/W system operates between the stations (hundreds of Kms

apart) having number of repeaters in between.

Radio equipment required at the terminal with :-

1. BASE BAND PROCESSING EQUIPMENT.

2. I.F MODULATION EQUIPMENT, I.E. MODULATOR AND DEMODULATOR.

3. UP CONVERTER/ DOWN CONVERTER.

4. POWER AMPLIFIER

5. ANTENNA SUB. SYSTEM

Fig : 7 Typical MW Radio System

4.11 MINILINK

Mini link is a microwave solution used to provide microwave link betweenBSC & BTS. Minilink microwave radios provide an efficient and rapid way of

developing wide converge telecommunication networks. The use of Minilink is

particularly suited for cellular applications because of its flexibility concerning

capacities, configurations and space required. It also offers fast deployment in all

project phases for planning to commission. Minilink is ideal for quickly providing

medium capacity-links in temporary or permanent, mobile or fixed communication

networks. It can be used anywhere within the network, where one to seventeen 2-


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Mbps transmission lines are required. As there is no need for heavy masts or towers, it

can quickly be mounted on existing building or structures.

Fig : 8 Mini link ODU with Antenna

4.11.1 TECHNICAL DATA

The Mini-Link exists in three different versions, which works in a similarway, but they have different capacity and cover different frequency

bands as given below. They are:

MK II (old version)

Mini-Link C

Mini-Link E

4.11.1.1 Mini-Links

Traffic capacities (Mbps): 2, 2x2, 4x2, 2x8, 8x2

Frequency bands (GHz): 15, 23, 26, 38

4.11.1.2 Mini-Link E

Traffic capacities (Mbps): 2x2, 4x2, 2x8, 8x2, 34+2

Frequency bands (GHz): 7, 15, 18, 23, 26, 38

4.11.2 SYSTEM OVERVIEW

A MINI-LINK Network Element (NE) can, from a hardware and installation

point of view, be divided into two parts:


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• Indoor part,

• Outdoor part

4.11.2.1 Outdoor Unit

• Radio Unit

• Compact antenna

4.11.2.2 Indoor Unit

Modem unit (MMU)

Traffic unit (TRU)

Access Module Magazine(AMM)

From a functional and configuration point of view, an NE can be divided into

the following parts:

Basic Node: The Basic Node holds the system platform providing traffic and

system control, such as traffic routing, multiplexing, protection mechanisms and

management functions. It also provides traffic interfaces, PDH, SDH and Ethernet, for

connection to network equipment such as a radio base station, ADM or LAN. Finally,

it includes indoor mechanical housing, power distribution and cooling.

Radio Terminals Each Radio Terminal provides microwave transmission

from 2x2 to 32x2 Mbit/s, operating within the 7 to 38 GHz frequency bands, utilizingC-QPSK and 16 QAM modulation schemes. It can be configured as unprotected (1+0)

or protected (1+1).

4.12 BROADBAND VSAT

VSAT broadband is similar to cable and DSL services for your computer

which provides high performance two-way connectivity for Broadband access as well

as offers value added satellite based services ( content delivery ) with the added

advantage to serve remote and inaccessible areas of country and a cost-effective

networking solution for Corporate bodies, Training Centers, Hospitals, Stock

exchanges, Banks, Technical institutions, Government, military etc. with high level

functionality and hence VSAT broadband is another option for a high-speed Internet

connection that is considered to be one of the best technologies available today.

VSAT technology is a secure and reliable medium to connect geographically

dispersed locations and represents a cost effective solution for users seeking an

independent communication network connecting to the global network. In a situation

where other connectivity options are not feasible, broadband VSAT of BSNL

(operating in Ku band of electromagnetic spectrum i.e. 11 to 18 GHz) offer value


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added satellite based services capable of supporting- Broadband internet access,

VOIP, video conferencing, IP multicast, Local Area Network, voice, Fax and can

also provide powerful dependable private communication solutions.

VSAT stands for Very Small Aperture Terminal. VSAT is a device (also

known as an “earth station”) that is used to send and receive wireless transmissions bysatellite. Millions of VSATs are in use around the world, allowing people to send and

receive two-way data, voice or video transmissions by bouncing signals off of

satellites in orbit.

Fig : 9 VSAT Network

The "very small" component of the VSAT acronym refers to the size of the

VSAT “antenna” or “dish” - typically about 2 to 5feet (0.55-1.8 meters) in diameter

for Ku-band systems - that is mounted on a roof, attached to a wall or placed on the

ground and is capable of both receiving and sending satellite signals. VSAT systems

can be designed to serve both broadcast and interactive applications whether data,

voice or video, which are now being served by terrestrial lines and can be operated in

either single or multi-user environment.

VSAT Equipment is mainly consist of-

ODU ( Outdoor Unit )

IDU ( Indoor Unit ) as shown in Fig.10


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4.12.1 OUTDOOR UNIT (ODU):

The outdoor unit system is specifically optimized for use with the Indoor Unit and

consists of:

Transmit / Receive Dish (Antenna) (0.75m - 1.8m)

Block Up-converter (BUC) (1W-2W)

Low Noise Block-Down-converter (LNB)

Feed Assembly

Dish

LNB

BUCFeed

horn

SAT Tx

SAT RX

USB

Ethernet 10/100

BaseT (RJ-45)

Telephone Jack

for VoIP (RJ-11)

100-240 VAC

(Optional -48V

DC)

ODU IDU

Dish

LNB

BUCFeed

horn

SAT Tx

SAT RX

USB

Ethernet 10/100

BaseT (RJ-45)

Telephone Jack

for VoIP (RJ-11)

100-240 VAC

(Optional -48V

DC)

ODU IDU

Fig : 10 ODU & IDU

BUC: - Block up-converter converts incoming I.F. (from IDU) to R.F. transmitting

frequency, amplifies it and passes it to feed.

LNB: - LNB amplifies incoming R.F.(Radio Frequency) from feed using low noise

amplifier, converts it to I.F. and passes it to IDU

4.12.2 IDU (INDOOR UNIT):

On receiving side, converts I.F. (Intermediate Frequency) from ODU to base

band signals which may be data, video or voice. On transmitting side, converts base

band signals to I.F. and passes them to ODU. I.F. is generally in L band. R.F. can be

in C, Ku or Ka bands.

The indoor unit may be a small desktop box, or it may be (as in this case) a

network module integrated with a router providing VSAT network connectivity just

as any other network module and provide flexible Interfaces like Ethernet 10/100


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BaseT (RJ45), USB with maximum download speed of up to 4 Mbps and maximum

upload speed of up to 2 Mbps.

4.12.3 BROADBAND V-SAT ARCHITECTURE

V-SAT networks can be arranged in point to point, star, mesh, star/mesh, and

broadcast configurations. The preferred arrangement depends on the kind ofinformation flow the network will service. A point to point network allows two-way

communications between two VSAT sites. A star network allows any number of

VSAT sites to have two-way communication with a central hub. A mesh network

allows two-way communications between any VSAT sites in a network. A central hub

is not necessary. Each site communicates to another site with a single satellite hop.

VSAT Broadband (Ku band VSAT) networks of BSNL designed in a hub-

and-spoke fashion as shown in fig. 11, with customer locations connecting directly

over the air to a central “hub” facility. The equipment at a customer site is a VSAT

receiver/router (similar to a DSL or cable modem), attached to a small dish mounted

on top of or outside the building. At the central hub facility, a large dish andsophisticated hub RF components receive and transmit to the remote sites, and route

information to and from the Internet or private networks via leased line.

Internet router is connected to BSNL National Internet Backbone using

multiple 2 Mbps leased line. All Remote VSAT locations are having private IP so that

remote VSAT users can connect to Internet.

HUB

VoIP

MLLNKu Band BSNL

Gateway,

Bangalore

VSAT

Satellite

INTERNET

MPLS

IDU

IDU

HUB ATA

ATA- Analog Telephone Adapter

HUBHUB

VoIPVoIP

MLLNKu Band BSNL

Gateway,

Bangalore

VSAT

Satellite

INTERNET

MPLS

IDU

IDU

HUB ATA


Ku Band

HUB/Gateway

HUB

VoIP

MLLNKu Band BSNL

Gateway,

Bangalore

VSAT

Satellite

INTERNET

MPLS

IDU

IDU

HUB ATA


HUBHUB

VoIPVoIP

MLLNKu Band BSNL

Gateway,

Bangalore

VSAT

Satellite

INTERNET

MPLS

IDU

IDU

HUB ATA


Ku Band

HUB/Gateway

Fig : 11 Ku band V-SAT Architecture


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4.12.4 V-SAT SERVICES OFFERED

The V-SAT Broad VSAT network allows secure, reliable and cost effective

data, voice and video transmission and enables an organization to deploy nationwide

different services over IP using the shortest time span.

LEASED LINES Through V-SAT on IP PLATFORM: 4Kbps onwards High speed Broadband Internet

VPN Networking

VOIP Telephony

Facsimile

Telemedicine

E-learning

IP multicasting

Video conferencing

Video streaming

Facsimile Distance Education

Banking

E-learning

On-demand services for WAN backup/disaster recovery etc.

4.13 DIGITAL SATELLITE PHONE TERMINAL (DSPT)

Digital Satellite Phone Terminal System (DSPT system or DSPS) project

involves setting up a VSAT (Very Small Aperture Terminal) Based network for

BSNL. The system consists of HUB Station and Remote Digital Satellite Phone

Terminals working in Ku-Band (Transmit Frequency is 13.75-14.5 GHz and Receiveis 10.7-12.75 GHz). DSPT Network provides PSTN connectivity to rural, remote,

inaccessible and hilly areas via INSAT (Indian National Satellite) or leased

transponder for DTS network. The VSAT system works in a star topology using

DAMA (Demand Assigned Multiple Access) technology.

The Hub of DSPT system will be composed of Indoor and Outdoor facilities. The

outdoor facility is a complete Antenna and RF path while the indoor comprises the

Hub Base-band and the other equipment:

The Hub of DSPT system comprises of Indoor facilities and Outdoor facilities.

4.13.1 INDOOR FACILITIES

Indoor facilities has following components,

a. Hub Base-band

b. Transit switch.

In the Indoor facility consists of redundant Hub-base band unit, a Transit

switch to provide connectivity to PSTN network, associated Data-Base servers,


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Billing system consisting of Billing system Hardware and software, the data

networking equipment consisting Firewall, web-server, Authentication server and

router to provide backend connectivity to the Internet. The base-band and remotes

have a NMS and its database to configure and manage the entire VSAT-based

network.

4.13.2 Outdoor facilities:

a. Antenna (8.1 Meter antenna assembly)

b. RF path: RF path consists of Transmit chain and Receive chain.

Transmit chain consists of

-ULPC (Up Link Power Control),

- Up Converter and

- SSPA (Solid State Power Amplifier) and

Receive chain consists of

- Trance reject filter,

- Radar reject filter,

- LNA (Low Noise Amplifier),

- Power divider and Down converter.


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Fig : 12 Typical Network Configuration of DSPT system

4.14 SUMMARY

Microwave links of short distances are generally allocated with higher

frequencies, because high frequency means high losses in air and thus it is good to

have short distances in these cases. Digital Microwave Radio Link Systems allow

transmission links to be established rapidly and easily to meet a variety of

transmission needs, delivering cost savings and enabling rapid network rollout. While

for distances like 20-50 Kms or so we use lower frequencies. PDH digital microwave

communication system work in 2.0GHz to 26GHz frequency range and provides 2

Mbps to 140Mbps date transmission.

Mini-Link microwave radios provide an efficient and rapid way of developing

wide-converge telecommunication networks. The use of MINI-LINK is particularly

suited for cellular applications because of its flexibility concerning capacities,

configurations and space required. It also offers fast deployment it also offers fast

deployment in all project phases for planning to commission. MINI-LINK is ideal for

quickly providing medium capacity-links in temporary or permanent, mobile or fixed

communication networks.


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The V-SAT Broadband technology is a cost effective solution for those who

want an independent, secured and reliable communications network to connect a large

number of geographically dispersed sites where any other connectivity options are not

possible to implement. This type of Internet connection is also great for areas that are

rural or are perhaps underserved by reliable Internet Service Providers. The V-SAT

Broadband service provides faster speeds, more flexibility, and better performance,making it an attractive network option for businesses of all types and sizes. V-SAT

broadband is a way to have the latest technology without having to go through a local

ISP. VSAT broadband is definitely a wave of the future.

4.15 SELF ASSESSMENT QUESTIONS

1. As a convention frequencies, above 1 GHz and up to 40 GHz are termed as….

2. Microwave transmission involves the sending and receiving of microwave

signals over a……...

3. M/W link involve ……………communication technology

4.

8 Mbps system in 2 GHz band is suitable for application as a …….haul system5. 6 GHz 140 Mbps Digital Microwave System is used for ……. route

applications

6. The antenna system consists of Main and ……….. antennas.

7. Each RF channel in this radio system is a (able) to have an additional capacity

of carrying one 2 Mbit/s pulse stream equivalent to 30 telephone messages,

what is called……………….

8. …………. counteracts the effects of fading by combining signals from Main

and SD antenna.

9.

…………. counteracts the effects of fading by combining signals from Main

and SD antenna.

10.

As a countermeasure against multipath fading, a time domain equalizer, calleda………………..

11. …………… is a microwave solution used to provide microwave link between

BSC & BTS.

12. It provides radio transmission links from 2 up to …………. Mbit/s, operating

within the 7 to ……. GHz frequency bands.

13. VSAT stands for …..

14. VSAT Equipment is mainly consist of …….

15. …………… converts incoming I.F. (from IDU) to R.F

16. The Hub of DSPT system comprises of ……………………..

Answer: Microwave, microwave link, line of sight (LOS), short, trunk, Space

Diversity (SD), wayside traffic, Space diversity, Space diversity, transversal

equalizer, Mini link, 17x2, 38, Very Small Aperture Terminal, ODU & IDU, Block

up-converter, Indoor facilities and Outdoor facilities,

4.16 REFERENCES AND SUGGESTED FURTHER READINGS

http://en.wikipedia.org/wiki/Microwave

www.eogogics.com/talkgogics/.../microwave-line-of-sight-systems

www.isd.mel.nist.gov/meso_micro/SPIE_Paper_4821-26.pdf

Microwave engineering - David M. Pozar

http://en.wikipedia.org/wiki/Microwavehttp://www.eogogics.com/talkgogics/.../microwave-line-of-sight-systemshttp://www.isd.mel.nist.gov/meso_micro/SPIE_Paper_4821-26.pdfhttp://www.isd.mel.nist.gov/meso_micro/SPIE_Paper_4821-26.pdfhttp://www.eogogics.com/talkgogics/.../microwave-line-of-sight-systemshttp://en.wikipedia.org/wiki/Microwave


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www.ericsson.com/ourportfolio/telecom-operators/mini-link -tn

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www.carlsonwireless.com/

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