23-07-2012, 04:02 PM
METEOR BURST COMMUNICATIONS
METEOR BURST COMMUNICATIONS.pptx (Size: 196.65 KB / Downloads: 41)
INTRODUCTION
Meteor burst communications (MBC), also referred to as meteor scatter communications, is a radio propagation mode that exploits the ionized trails of meteors during atmospheric entry to establish brief communications paths between radio stations up to 2,250 kilometres (1,400 mi) apart.
HOW IT WORKS?
The meteors, we will concern ourselves with, orbit around the sun in a path that coincides with the earth's.
These meteors occur at a rate of two to eight billion daily or roughly 50,000 per second.
As these meteors catch up with the earth-or are overtaken by it, they enter the atmosphere at a speed of 10 to 75 kilometers per second.
The friction caused by the meteor colliding with the atmosphere results in the vaporization of the meteor.
The vaporized trails are further restricted by the atmosphere, stripping electrons from the vaporized atoms, causing a trail of positive-charged ions and free electrons to form behind the meteor.
This phenomenon occurs at about 115 kilometers altitude and by 85 kilometers has completely burned out.
The ionized trails last anywhere from a few
seconds to only a few hundredths of a second, and it is these upon which Meteor Burst Communications (MBC)depend.
METEOR TRAILS
There are two ways a meteor trail redirects the radio wave, depending upon the density of the trail.
OVERDENSE TRAIL
It occurs during a meteor shower and has a free electron density great enough to prevent the radio wave from penetrating.
The wave reflects back to earth much like a beam of light reflects from a mirror.
Overdense trails have a long life, sometimes lasting up to two seconds.
These meteor showers , however, play only a small part in MBC operations because they seldom occur and are only a small fraction of the total number of meteors that fall upon the earth each day
UNDERDENSE TRAIL
It is the one best suited for Meteor Burst
Communications.
This trail, caused by the steady drizzle of meteors that fall upon the earth each day, is less dense and allows the radio wave to penetrate.
This penetration causes excitement among the electrons, which act as small dipole antennas, redirecting the wave back to earth in a scattering fashion.
These trails last only a fraction of a second, but because of their regularity they are more dependable
than meteor showers.
PROCEDURE
All MBC systems consist of :
a master station and
one or more remote stations or sensors.
Hardware at both the master and remote station usually consists of
a small laptop computer terminal with storage for message buffering,
a transmitter,
receiver, and
antenna.
The master station is responsible for locating a meteor trail that will permit the two stations to communicate.
To accomplish this, the master station transmits a probe that may consist of a simple, continuous tone on a fixed frequency with the remote station's receiver tuned to the same frequency.
The probe continues to bounce against various meteor trails until a suitable path exists between master station and remote.
The angle of incidence a:nd the angle of reflection determine the path.
METEOR BURST COMMUNICATIONS.pptx (Size: 196.65 KB / Downloads: 41)
INTRODUCTION
Meteor burst communications (MBC), also referred to as meteor scatter communications, is a radio propagation mode that exploits the ionized trails of meteors during atmospheric entry to establish brief communications paths between radio stations up to 2,250 kilometres (1,400 mi) apart.
HOW IT WORKS?
The meteors, we will concern ourselves with, orbit around the sun in a path that coincides with the earth's.
These meteors occur at a rate of two to eight billion daily or roughly 50,000 per second.
As these meteors catch up with the earth-or are overtaken by it, they enter the atmosphere at a speed of 10 to 75 kilometers per second.
The friction caused by the meteor colliding with the atmosphere results in the vaporization of the meteor.
The vaporized trails are further restricted by the atmosphere, stripping electrons from the vaporized atoms, causing a trail of positive-charged ions and free electrons to form behind the meteor.
This phenomenon occurs at about 115 kilometers altitude and by 85 kilometers has completely burned out.
The ionized trails last anywhere from a few
seconds to only a few hundredths of a second, and it is these upon which Meteor Burst Communications (MBC)depend.
METEOR TRAILS
There are two ways a meteor trail redirects the radio wave, depending upon the density of the trail.
OVERDENSE TRAIL
It occurs during a meteor shower and has a free electron density great enough to prevent the radio wave from penetrating.
The wave reflects back to earth much like a beam of light reflects from a mirror.
Overdense trails have a long life, sometimes lasting up to two seconds.
These meteor showers , however, play only a small part in MBC operations because they seldom occur and are only a small fraction of the total number of meteors that fall upon the earth each day
UNDERDENSE TRAIL
It is the one best suited for Meteor Burst
Communications.
This trail, caused by the steady drizzle of meteors that fall upon the earth each day, is less dense and allows the radio wave to penetrate.
This penetration causes excitement among the electrons, which act as small dipole antennas, redirecting the wave back to earth in a scattering fashion.
These trails last only a fraction of a second, but because of their regularity they are more dependable
than meteor showers.
PROCEDURE
All MBC systems consist of :
a master station and
one or more remote stations or sensors.
Hardware at both the master and remote station usually consists of
a small laptop computer terminal with storage for message buffering,
a transmitter,
receiver, and
antenna.
The master station is responsible for locating a meteor trail that will permit the two stations to communicate.
To accomplish this, the master station transmits a probe that may consist of a simple, continuous tone on a fixed frequency with the remote station's receiver tuned to the same frequency.
The probe continues to bounce against various meteor trails until a suitable path exists between master station and remote.
The angle of incidence a:nd the angle of reflection determine the path.