Mbc system

1

METEOR BURST COMMUNICATION

A SEMINAR ON:

2

•Introduction

•Meteor

•Principle

•Why now?

•Procedure for MBC

• Error correction

•Meteor scatter modes

•Technological advancements

•Advantages

•Shortcomings

•Applications

•Conclusion

•Future scope

•References

•Thanks3

4

Communication is very much significant in today's

environment

Meteor burst communication is a type of

communication technique

Basic idea is to bounce radio signals by using meteor

trails created

Attractive option for application including secure

independent reliable and low data rate communication

Those having orbit around sun in a path that

coincides with earth

Occur at a rate of 2 to 8 billion daily or roughly

50,000 per second

Enters at a speed of 75-80 kms per second

Friction between meteor and earth atmosphere cause

it to vapourise

5

Vaporization/burning

causes formation of trail of

ionized particles in E layer

This meteor trail is used

for communication called

meteor burst communication

It is also called as meteor

scatter communication or

meteor trail communication

Meteor shower from space

6

The rate at which meteors enter the Earth’s atmosphere

peaks at around 6:00 AM local time

Between midnight and 6:00 AM the Earth is turning into

the path of oncoming meteors

Meteors strike with higher velocity during this time.

7

8

The meteor strike rate also varies annually.

Meteor rates are greater in summer than winter

The frequency that can be reflected by the trail depends

upon intensity of ionization which depend upon the

relative size of meteor

Typical range is between 30 MHz and 50 MHz

9

10

As meteors are vaporized in the upper

atmosphere, they leave behind ionized trails

sufficiently dense to reflect radio waves in the

HF and VHF range.

A long trail lasts only 15 seconds – most trails

are less than 1 second long

11

Trails are classified as:

Under dense (n < 2*1014 m-1)

Over dense (n >= 2*1014 m-1)

12

Over dense: Reflection Under dense: excitation

Geminids meteor shower of 2010

13

This system have low error rate and safer than

satellite communication

Safety of data transfer

Available resource

14

15

•Master station, receiving

station/sensors

•Transmitter-receiver and Antenna

•Small laptop for storage with

message buffering

•Transmission can be simplex half

duplex or full duplex

16

• Antennas do not need

to have high gain

• Lower-gain antennas

illuminate more trails

• Higher-gain antennas

illuminate weaker

trails

17

Master station sends a

probe of simple continuous

tone of fixed frequency

signals

When receiver receives

probe it gives an

acknowledgmentTransmission of data occurs

18

The period of searching

between usable trails is known

as the wait time.

communications are buffered

into storage

If more remote stations are present the probe will

contain address code of intended receiver

If any other stations receive this probe it will remain

idle

19

20

Since individual trails last for only a short time, information must be sent in small packets

The exact time a trail will occur is unknown, so the information must be sent repeatedly.

To keep the SNR high, the signal bandwidth should be as narrow as possible.

21

Should prevent the transmission of data when

no suitable path exists

Two methods

1)Forward error correction code(FEC)

2) Automatic repeat request(ARQ)

22

The earliest experiments with MS

communications used CW and AM phone.

Today, the following modes are used:

HSCW

SSB

FSK-441

Most of the meteor Scatter communication

now uses FSK-441

23

CW sent at high speeds (200 wpm or more)

HSCW activity occurs primarily in the following band

segments:

50.250 – 50.300 MHz

144.100 – 144.150 MHz

222.000 – 222.200 MHz

24

Used primarily on 6 m

Can be used with random meteors, but generally

works better during a meteor shower

SSB activity occurs primarily in the following band

segments:

50.125 – 50.250 MHz

144.200 – 144.250 MHz

25

Uses triplets of 4 tones to transmit

data

882, 1323, 1764, 2205 Hz

Each character is sent as a 3 tone sequence

43 Character alphabet (letters, numbers . , / ? # $ <sp>)

Single tone characters used for shorthand messages:

26

Data rate = 147 characters per second (3 tones/char)

Used for meteor scatter communications

Most activity takes place near 50.270 MHz

27

JANET by Canada

COMET(COmmunication by MEteor Trails) by NATO

SNOTEL(SNOw pack TELmetry) by united states

AMBCS(Alaskan Meteor Burst Communication System)

28

29

VHF convertors: converts any radio terminal into a

MBC terminal

ADAPTIVE SIGNAL RATES: signal rates can be

varied according to SNR from trail to trail and within

the trail

ADAPTIVE FILTERING: filtering allows high

efficiency at receiver side

Independent :user owns the system. Less likely to

compromised

Uses only one frequency: Advantages over high

frequency system.

Light and durable equipment and easily deployed

Able to survive nuclear war

30

Strong confidentiality

Easy to prevent the influence of interference station

Communication, good stability, less affected by the

ionosphere disturbances and Aurora

Sunspot activity is relatively small.

31

ADVANTAGES

Very low error rate about 1/50000

Once the trail burns one cannot know the

location of Transmitter or Receiver.

32

Low data rate. Not suitable for high

volume users

Limited by distance

Not suitable for voice communication

33

1.Natural satellite:

Equivalent to natural satellite

But less expensive

No need to launch satellite

34

2.During war

Communication during war

Not affected by nuclear

explosion or interference

Stations are remote

35

3.Civil:-

Aircraft and vehicle scheduling

Forest fire alarm

Harsh environment

communication

Data acquisition

Broadcasting

36

Very effective mode of communication

By using advanced technologies data rate can be

improved

Can replace satellite

37

A naturally occurring phenomenon, can improve

the network performance.

Able to replace existing communication

technique

38

National communication system –Technical

information bulletin

Wikipedia

http://prezi.com/nmconopethm-/meteor-burst/

www.nsa.gov/public_info

39

40