Page 200 - DCAP311_DCAP607_WIRELESS_NETWORKS

Wireless Networks

Notes 4. The EARLY BIRD series was a slightly more capable and longer-lived version of INTELSAT
II.
5. In 1965, ABC proposed a domestic satellite system to distribute television signals.
6. The last major geosynchronous satellite project was the Defense Department’s ADVENT
communications satellite.

7. An aeronautical satellite was proposed in the mid-1970s.
8. A special type of LEO is the Polar Orbit.

12.2 Meteor Burst Communications (MBC)

Meteor Burst Communications use a form of radio communications system that is dependent
on radio signals being scattered or reflected by meteor trails. Meteor burst communications is
a specialized form of propagation that can be successfully used for radio communications over
paths that extend up to 1500 or 2000 km. Meteor burst communication provides form of radio
propagation that can be sued when no other form of radio propagation may be available.
!

Caution While data has to be transmitted in bursts and there may be delays, it provides a
very useful form of non-real-time communications that can be used in many circumstances.

Seamless full-coverage communications technology offers the opportunity for immediate
penetration of a multitude of potential high yield markets. The system can easily be linked to the
fixed telephone network to send and receive e-mail in areas where there is no telephone cable
in the ground. Interconnection with GSM networks to send and receive SMS messages in non-
covered areas is also possible.

Government and commercial organizations in Africa are considering the use of the MBC system in
rural areas for elections, education, spreading national news, population registration, payment of
pensions, and remote reading of electricity meters. Additional serious options include tracking
and tracing of trucks, trailers and railway wagons to optimize logistics and prevent theft.

12.2.1 Historical Overview

The fact that the ionized trails of meteors entering the earth’s atmosphere can reflect the radio
signal has been known since the early 1930s, when Pickard noticed that bursts of long distance,
high frequency propagation occurred at times of major meteor showers. In 1935, Skellet found
that when a meteor entered the earth’s atmosphere, the denser air caused the meteor to heat up
and eventually burn, creating an ionized trail which could be used to reflect a radio signal back
to earth. Skellet postulates that the mechanism was reflection or scattering from electrons in
meteor trail. During the World War II radio engineers observed meteor trail echoes, which were
sometimes confused with incoming missiles.

It was not until after the war when radio technology had extended into the VHF and UHF bands
that radio engineers became interested in the meteor scatter phenomena. From the 1950s through
the 1970s, meteor burst technology was studied and actual tests were conducted to determine the
feasibility of using meteor trails. Some interesting information were found. Unfortunately, until
the availability of integrated solid-state microcomputer, meteor burst communications was not
considered practical except for slow-speed data system. The waiting time between meteor trails
seemed too long for modern use.

A usable system became operational when Canada installed the JANET systems between Toronto
and Port Arthur in the 1950s. Another one-way link was installed between Bozeman (Montana)
and Stanford (California). In the late 1970s, the Alaska SNOTEL (SNOpacTELemetry) system was
installed to provide meteorological information from remote locations through Alaska.

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