Rf noise and radio astronomy
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RF Noise and Radio-Astronomy. A Brief History of Radio Astronomy. 1860's Maxwell develops equations that govern electromagnetic (EM) waves. 1860's-1930's physicists suspect celestial bodies to emit EM waves of non-visible wavelength.

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Rf noise and radio astronomy

RF Noise and Radio-Astronomy


A brief history of radio astronomy

A Brief History of Radio Astronomy

  • 1860's Maxwell develops equations that govern electromagnetic (EM) waves.

  • 1860's-1930's physicists suspect celestial bodies to emit EM waves of non-visible wavelength.

  • 1930's Karl Jansky discovered interference patterns in voice communications.


A brief history of radio astronomy1

A Brief History of Radio Astronomy

  • 1933 Through investigation and consultation he was able to track the source of interference to the center of our galaxy.

  • 1933-present This discovery inspired other scientists and engineers to come together to design and build radio telescopes.


What is radio astronomy

What is Radio Astronomy

  • The sub-category of the natural science Astronomy concerned with Radio Frequency emanation from celestial bodies.


Why is radio astronomy important

Why is Radio Astronomy Important

  • A Paramount tool for:

  • Discovery

  • Science

  • Curiosity

  • Explanation

  • Many important scientific discoveries have been proven by the use of radio astronomy.

  • The Big Bang

  • Cosmic microwave background radiation

  • New planets and galaxies

  • Radio galaxies, quasars, pulsars, masers


Listening and broadcasting

Listening and Broadcasting

  • “listening to space” The principle is simple. Implementation is not

  • Radio signals picked up by antennae are converted into audio signals.

  • These audio signals can be analyzed to tell us more about space.


How radio astronomy is implemented

How Radio Astronomy is Implemented

  • An “image” of radio space is acquired by scanning space with an antenna.

  • The antenna will pick up the emanations very similar to wireless communications.

  • The data that is read in is sorted by frequency and shifted to a visible wavelength.


How radio astronomy is implemented1

How Radio Astronomy is Implemented

  • Scanning an area will give us an image of the area.

  • Astronomers require an extremely large signal to noise ratio to produce a valuable image or audio signal.


The problem

The Problem

  • The frequencies of interest to Radio Astronomers correspond to frequencies RF engineers use for communications.

  • The man-made radio emissions are intercepted by the radio astronomers.

  • This corrupts the astronomers data leading to inaccuracies in observations and interpretations.


A contemporary concern

A Contemporary Concern

  • In January 2012 the World Radio-communication Conference's topic was interfering with radio astronomy

  • The relationship between radio astronomer and RF engineer once a great partnership has now grown tense.


Allocation

Allocation

  • Frequencies that are chosen for allocation are specially chosen for radio astronomy.

  • The frequencies allocated to radio astronomy:

  • 608 – 614 MHz,

  • 1406,

  • 1420 – 1666 MHz,

  • 23, 33, 41, 61, 94 GHz


Much is already lost

Much is Already Lost

  • RF ranges have encroached deeply into the observable frequencies.

  • The 71-275 GHz portion of the radio spectrum is the portion that is in danger

  • Much of the 3-30 GHz range has already been lost to the widespread use of radar, satellite communications, and wireless telecommunications.


Communication equipment

Communication Equipment

  • Examples of equipment that compete for radio astronomy:

  • UAS – unmanned aircraft services need 50MHz of useful spectrum

  • Satellite Down links – Iridium satellite system, GLONASS

  • Spectroscopy

  • Imaging

  • radar

  • Other communication devices (short distance, high power)


Communication equipment1

Communication Equipment

  • Spill over from communication is also a prominent problem

  • The equipment in place is designed to operate in it's allocated range.

  • The equipment “spills” over into the radio astronomy range.


Enforcement

Enforcement

  • There is no agreement on how this issue should be addressed

  • The regulatory groups are not sure if it should be dealt with by a universal regulatory body or a case by case basis.

  • There are regulatory measures in place to protect astronomers but they are rarely enforced.


The problem revisited

The Problem Revisited

  • The spectral range that is used in radio astronomy is as of yet largely unexplored and somewhat unclaimed, but as technology progresses other uses for these frequencies are being discovered.

  • The RAS and EESS are becoming more and more concerned.


The solution

The Solution

  • There is no easy solution to this problem.

  • Radio astronomy is of paramount importance in contributing to our understanding of the universe.

  • Our expanding need for better communications requires more and more bandwidth.

  • Some temporary solutions have been implemented and are as follows.


Radio interferometry

Radio Interferometry

  • To combat the signal to noise ratio problem radio interferometry has been developed.

  • Interferometry is using arrays of antennas to produce multiple sets of data and filter out the noise.

  • The problem: a very expensive solution as many antennae are needed, and it is still subject to noise.


High selectivity antennae

High Selectivity Antennae

  • This poor solution works on a very basic principle.

  • If we examine only a small portion of the sky we can eliminate much of the radio noise picked up.

  • The problem: we lose much of the important information as well.


Satellite radio astronomy

Satellite Radio Astronomy

  • Best results in removing noise from the signal is to remove the antenna from the noise.

  • By putting the antenna in far orbit astronomers hope to eliminate all man made noise from the equation.

  • The problem: This is a very expensive solution. Space has become cluttered with communications satellites and “space garbage” leaving little room for radioastronomical satellites.


Stewardship

Stewardship

  • Conclusions Drawn:

  • There is no good solution as of now for protecting radio astronomy from communications equipment

  • We as engineers must act as stewards of science when designing communications equipment.


Questions

Questions


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