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Frequency Management Aka why you can detect any astronomical signals at all Dr. Karen O’Neil Green Bank Site Director.

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Presentation on theme: "Frequency Management Aka why you can detect any astronomical signals at all Dr. Karen O’Neil Green Bank Site Director."— Presentation transcript:

1 Frequency Management Aka why you can detect any astronomical signals at all Dr. Karen O’Neil Green Bank Site Director

2 Frequency Management Does it really matter?

3 Frequency Management Does it really matter? GBT observations with pocket digital camera ON and OFF

4 U.S. Frequency Allocation chart The United States has set aside some frequencies for astronomy…

5 U.S. Frequency Allocation chart The United States has set aside some frequencies for astronomy… But they are few and far between

6 U.S. Frequency Allocation chart The United States has set aside some frequencies for astronomy… But they are few and far between Astronomy is not limited to pre-designated frequencies. Redshift spreads even the allocated astronomy frequencies, such as 1420 MHz, across more than 1000 MHz in band Allocation process cannot allow for new discoveries, exploration of frequency space Many of the astronomy allocations are shared with other spectrum users What do we do??? Astronomy is not limited to pre-designated frequencies. Redshift spreads even the allocated astronomy frequencies, such as 1420 MHz, across more than 1000 MHz in band Allocation process cannot allow for new discoveries, exploration of frequency space Many of the astronomy allocations are shared with other spectrum users What do we do???

7 Frequency Management There are three ways to handle interference: – Spectrum allocation – Regional protection – Post-observation excision

8 Frequency Management There are three ways to handle interference: – Spectrum allocation – Regional protection – Post-observation excision The art of Spectrum Management Algorithm development Pattern recognition

9 Spectrum Allocation Three Regions (International Telecommunications Union)

10 Spectrum Allocation Three Regions (International Telecommunications Union) All countries are sovereign inside their border (Radio waves always know where to stop, eh?) No country can operate a satellite transmitter without ITU-R permission (Border issues are often important) Most general set of rules (Radio Regulations) is an international (every 4-5 years through the UN) All countries are sovereign inside their border (Radio waves always know where to stop, eh?) No country can operate a satellite transmitter without ITU-R permission (Border issues are often important) Most general set of rules (Radio Regulations) is an international (every 4-5 years through the UN)

11 Spectrum Allocation IUCAF: International Scientific Committee on Frequency Allocations for Radio Astronomy and Space Science Sponsored by: – International Astronomical Union (IAU) – The International Union of Radio Science (URSI) – The Committee on Space Research (CoSPAR) Represents astronomical interests at international spectrum meetings U.S. astronomy is represented through the National Science Foundation

12 Spectrum Allocation Spectrum bands are allocated to ’services’: – Service = purpose or application – Most services are ‘active’ –they transmit Radio astronomy and Earth-sensing are ‘passive’ (only listen) Radar astronomy and EE-SS (active) also transmit but are distinct Concept of “use” elusive for passive services Examples of “services”: – Radiolocation = radar – Radionavigation/Radio Navigation Satellite Service = GPS – Fixed service (terrestrial point to point) – Fixed-satellite service (space-earth, earth-space) – Mobile-satellite service (satellite phones) – Broadcasting (TV)

13 Spectrum Allocation Spectrum allocation is extremely important to protect radio band It works very slowly, and new laws/protections can take many years In the U.S. the spectrum is typically sold by the FCC – Radio astronomy is at a distinct disadvantage – Sharing of even radio astronomy spectrum is likely coming soon

14 Regional Protection Regional protection comes in two ways: – Natural or man made protection – Legislation

15 Regional Protection Regional protection comes in two ways: – Natural or man made protection – Legislation

16 Green Bank: Location A high mountain valley with natural terrain shielding A great place for a Radio Astronomy Observatory!

17 National Forests around Green Bank Green Bank State and National Forests foster low population growth.

18 Regional Protection Regional protection comes in two ways: – Natural or man made protection – Legislation

19 Regional Protection Regional protection comes in two ways: – Natural or man made protection – Legislation Green Bank has two radio quiet zones: – National Radio Quiet Zone – West Virginia Radio Astronomy Zone

20 National Radio Quiet Zone Established by FCC and NTIA on Nov 19, Established in law before radio telescopes were built and before any frequency allocations to Radio Astronomy. +13,000 mi 2 of WV, VA and MD As part of the normal coordination process, the NRQZ office comments on new or modified, permanent, fixed radio transmitters. Work with applicants in finding a mutually acceptable solution to their coverage needs and our protection criteria.

21 1.Only bounded area in the US requiring coordination of new or modified, permanent, fixed transmitters. 2.The NRQZ is a unique and valuable resource in an ideal location. 3.Centered between Green Bank and Sugar Grove.

22 WV Radio Astronomy Zoning Act August 9, 1956: Protection from interference by any electrical equipment within 10 miles

23 Regional Protection Natural + legislative protection provide the best environment – Legislation provide protection within designated region – Natural barriers protect from transmissions inside and outside the protected zones Power Transmitted in the direction of the GBT (depends on the antenna and what direction it is pointing as well as the power into the antenna) Frequency and Bandwidth over which the power is distributed (depends on the technology being used) Path Length Natural Obstacles (mountains) in the path (if the attenuation manmade obstacles is known, this too can be considered)

24 Regional Protection Regional protection comes in two ways: – Natural or man made protection – Legislation Green Bank has two radio quiet zones: – National Radio Quiet Zone – West Virginia Radio Astronomy Zone – Combined protection of two quiet zones is very powerful Two new quiet zones now exist in the world: – South Africa (protection for MeerKAT, Kat64, SKA) – Australia (protection for SKA in Western Australia)

25 Community Agreement Even with legal protection community agreement is vital – Continuous challenge with outreach, education, and helpTeach the community who you are and why you needs the protection – Show the community the value of radio astronomy locally and scientifically – Help the community to mitigate the effects of the Quiet Zone(s) as possible This is the most difficult challenge, and one which must be continuously considered

26 Spectrum Management is a challenging issue which must be tackled for radio astronomy to flourish Crowding of the spectrum will increase, and the space for radio astronomy will shrink You can help! Report RFI whenever you see it in your data Be conscious of your use of electronic devices near radio telescopes Work with the IAU, URSI, other organizations to protect the radio spectrum


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