Preparing for the New Area of Radio Astronomy
By: Tam Huynh & Bob Bissell

Bob Bissell


Okanagan Kootenay

District Office


Tam Huynh

Communications Engineer



Synthesis Telescope


The Dominion Radio Astrophysical Observatory (DRAO) in Penticton recently hosted RFI2004, an international workshop dedicated to Radio Frequency Interference and Interference Mitigation.  


The workshop was held July 16-18, 2004.  Astronomers and engineers from around the world were invited to the Okanagan to find ways to minimize the impact of the growing levels of man-made radio interference in space.  


For radio astronomers, the Radio Frequency Interference (RFI) environment continues to worsen, making this a critical issue in the development of the next generation of radio telescopes. Radio Astronomy requires a greater spectrum for its services, development of new radio telescopes and greater protection.


Industry Canada was invited to RFI2004 to discuss the Spectrum Management Operation.  We brought the Spectrum Explorer, which was mounted on a mobile trailer, to demonstrate some of the operations of Spectrum Management measurement and analysis.  Gord Herrmann, Greg Corbett and Micheal Amyotte from the Okanagan Kootenay District Office were on site to demonstrate the trailer to delegates.  IC's demonstration was extremely successful, with approximately 25 of the 75 delegates touring the trailer.


The workshop was attended by Bob Bissell, Tam Huynh and Chantal Gazaille from DG Spectrum Engineering.  The seminars proved to be very interesting, covering a range of issues from the scientific, technical and regulatory issues associated with Interference Mitigation, to field experiences and demonstrations of new techniques. 


RFI2004 was a precursor to the Square Kilometre Array Conference (SKA04), an international meeting to discuss and refine the science goals and telescope concepts for the Square Kilometre Array (SKA), the world's largest radio telescope, currently being planned for construction in the next decade. 


Many of you may be still be asking yourselves why these issues are so significant.  


Basically, to study distant sources, scientists from around the world need to be able to decipher radio emissions from the universe.  These are currently being masked by local signals.  To fulfill its objectives of discovering the universe, the New Radio Astronomy requires a greater allocation of spectrum for its services, more advanced radio telescopes, and more protection. 


The Dominion Radio

Astrophysical Observatory (DRAO)

in Penticton


The full array of DRAO's

Synthesis telescope

In current practice, radio-astronomic observations are done within frequency bands allocated for this service. Due to the general expansion of the universe and the doppler effect, the observed frequencies of the spectral features of very distant sources are ‘red-shifted’ [1] to lower frequencies that can be up to 5 times smaller than their original frequencies.  


In New Radio Astronomy, advanced radio telescopes will be required to ‘see’ across a wider range of spectrum, including frequencies well outside the bands presently allocated to the radio astronomy service.  For example the 21 cm spectral line (1400-1427 MHz, excited by interstellar neutral hydrogen HI), which has a rest frequency of 1400.4057 Mhz, can shift to a lower frequency and be observed at 430 Mhz for a distant quasar.


The intensity of radio astronomy signals is well below that of man-made signals, yet the observations in the New Radio Astronomy need to mitigate the effects of human-generated interference. In other words, it's a crowded and noisy universe.

New methods and techniques for RFI mitigation have been developed and were presented at RFI2004 by the research community in radio astronomy.  One way to do this is by establishing radio-quiet zones that call for protection from many levels: global regulatory protection (ITU Radio Regulations), local protection (Regulations at national level), and self-protection (computers, electronics associated with telescope control, signal processing). 


There are already some existing Radio quiet zones in the world [2], for example Greenbank, West Virginia set one up in 1956; the 300m Arecibo Radio Telescope in Puerto Rico; the Giant Meter Wave Radio Telescope GMRT in Pune, India; the Atacama Large Millimeter Array ALMA, in the Atacama Desert, Chile.

The Square Kilometre Array is a global project to design and build a next generation of radio telescope that will have advanced features.  These will include a sensibility 100 times higher than current radio telescopes, a huge collecting area of one square kilometre. 


Eleven countries are participating to this project: Australia, Canada, China, Germany, India, Italy, Poland, Sweden, the Netherlands, UK, and USA.  Candidates competing for the SKA sites are: Australia, South Africa, and China. 


In the design of SKA concept and technology, seven proposals from Australia, Canada, China, Europe, India and the US are competing to gain acceptance. A detailed description of the Canadian proposal, the “Large Adaptive Array", can be viewed at NRC's web site.  A description of the SKA project and these proposals are found at www.skatelescope.org.  In the SKA timeline, the site and concept selection will be done by 2005 and 2007 respectively; operation of the SKA starts by 2020.

Besides Radio Frequency Interference (RFI) mitigation techniques, the New Radio Astronomy has to gain the support of regulatory bodies at various levels, from global regulations (through ITU-R, WRC) , regional (CITEL, CEPT, APT) to national (Industry Canada) [1].  Other sources of RFI that are growing in importance and may become disturbing in the near future are: ultra wideband applications, power line communication system, licence exempt devices operating in the 5Ghz band with transmit power up to 1W.

While the Radio Astronomy service is preparing to enter a new area, Canada is present and well represented in the community.  Dr. Ken Tapping from the National Research Council, Herzberg Institute of Astrophysics at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton sits in the TG 1-8 of ITU-R and is an IUCAF member.  As well, the DRAO was the host of RFI2004 and SKA2004. 


Although not a candidate for the SKA site, Canada is one of the seven proposals in the design and development of the SKA technology, with the Large Adaptive Reflector (LAR) concept being developed at DRAO.  This is the process where several reflective panels positioned to form a parabolic dish are used to converge radio signals from space to a feeder suspended at the focus point of the parabolic dish by a tethered balloon at least 500m overhead.  


On the protection issue, DAO is also concerned about the recognition and establishment of the observatory as a radio-quiet zone. There is a housing development and a golf club on the road to the DRAO (about 2km away). Another concern is the Coordination with the US for interference from south of the border (i.e., interference from Aeronautical Mobile services in Monumental, WA [3]).


These concerns are all valid and will hopefully be managed successfully in the future.  Eliminating interference will ensure a bright future for Radio Interference, and the DRAO and IC's SITT will definitely be playing a role.



[1] Spectrum Management for Radio Astronomy, Proceedings of the IUCAF Summer School, 2002
[2] Jim Cohen, Radio-Quiet Zones: National and International Perspectives, EMC 2004
[3] Sharing analysis between Aeronautical Mobile services in Monumental Mountain, WA, US and Dominion Radio Astronomy Observatory in Pentiction, BC, Canada. Industry Canada, Doc. TN-277


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