Harvey LisztArecibo July 2005 Harvey S. Liszt NRAO, CHARLOTTESVILLE.

Harvey Liszt Arecibo July 2005

International & national& national

Spectrum Managment

Harvey S. Liszt

NRAO, CHARLOTTESVILLE


What is it, exactly?

• ‘Everyone’ knows that there is heavy demand on the finite resources of the RF spectrum

• So, use of the spectrum is heavily regulated to prevent interference among users and uses

• Making the regulations work/making new regulations is called “spectrum management”

• The lowliest job at any observatory– There are far more “spectrum managers” than

astronomers (in the real world, that is)(in the real world, that is)


What is interference?

• Interference is unwanted signal occurring in a band which has been allocated to other uses

• When you observe outside the bands allocated to radio astronomy you may see intentional radiation which is someone else’s signal

• Inside a RA band, unwanted signal is quite likely to be generated by the observatory

• Interference is what happens when SM FAILS


What is an allocation

• Spectrum bands are allocated to ’services’– Service = purpose or application– Most services are ‘active’ – they transmit– Radio astronomy and Earth-sensing are ‘passive’

• RAS and EE-SS (passive) only listen• Radar astronomy and EE-SS (active) also transmit but

are distinct

• Concept of “use” elusive for passive services – FCC considers spectrum “unused” just where we

work best

Examples of services

• Radiolocation = radar

• Radionavigation

• Radio Navigation Satellite Service = GPS

• Fixed service (terrestrial point to point)• Fixed-satellite service (space-earth, earth-space)

– terminals on 7-11’s, home satellite internet

• Mobile-satellite service (satellite phones)

• Broadcasting (TV) – known as the BSHarvey Liszt Arecibo July 2005

What kind of service is RAS?

• 1.5 radio waves or hertzian waves: Electromagnetic waves of frequencies arbitrarily lower than 3 000 GHz, propagated in space without artificial guide. [Radio extends to 100

• 1.6 radiocommunication: Telecommunication by means of radio waves.

• 1.7 terrestrial radiocommunication: Any radiocommunication other than space radiocommunication or radio astronomy.

• 1.13 radio astronomy: Astronomy based on the reception of radio waves of cosmic origin.

• [THESE ARE FROM THE RADIO REGULATIONS]


How does RAS operate?

• 1.16 allocation (of a frequency band): Entry in the Table of Frequency Allocations of a given frequency band for the purpose of its use by one or more terrestrial or space radiocommunication services or the radio astronomy service under specified conditions. This term shall also be applied to the frequency band concerned.




• 4.6 For the purpose of resolving cases of harmful interference, the radio astronomy service shall be treated as a radiocommunication service. However, protection from services in other bands shall be afforded the radio astronomy service only to the extent that such services are afforded protection from each other.




• 4.6 For the purpose of resolving cases of harmful interference, the radio astronomy service shall be treated as a radiocommunication service. However, protection from services in other bands shall be afforded the radio astronomy service only to the extent that such services are afforded protection from each other.

• Bottom line: RAS has standing only to the extent that it may experience interference, which can only happen inside RAS bands, so having allocations is necessary to participation in spectrum management


• 4.4 Administrations of the Member States shall not assign to a station any frequency in derogation of either the Table of Frequency Allocations in this Chapter or the other provisions of these Regulations, except on the express condition that such a station, when using such a frequency assignment, shall not cause harmful interference to, and shall not claim protection from harmful interference caused by, a station operating in accordance with the provisions of the Constitution, the Convention and these Regulations



• 4.4 Administrations of the Member States shall not assign to a station any frequency in derogation of either the Table of Frequency Allocations in this Chapter or the other provisions of these Regulations, except on the express condition that such a station, when using such a frequency assignment, shall not cause harmful interference to, and shall not claim protection from harmful interference caused by, a station operating in accordance with the provisions of the Constitution, the Convention and these Regulations

• Bottom line: RAS is free to observe in any band but may cry “foul” only when there is ‘harmful interference’ to RAS in RAS bands.



RAS is Unique

• RAS is the only service which uses spectrum outside its own allocated bands

• Only service which uses practitioners as its amateurishamateurish spectrum managers



The world is flat– ITU-R Regions


Part of the FCC version of the frequency table


Deconstruction


WRC00

Allocations now extend up to 275 GHZ

Some lesser protections



US74 … Catch 22?


US74

• FCC has considered cell phones on planes

• 2nd harmonic in ‘protected’ OH band @ 1665

• 300 commercial aircraft are in direct line of sight to GB at any moment during a typical day

That’s the status quo – what’s it to you?

• When you find an extraneous signal in your data, YOU can go to the frequency allocation table and see what is transmitting there!

• If YOU were pointing the GBT toward the geosynchronous satellite belt and searching for a H2O maser in a galaxy at z = 0.66, YOU would find that this band is used for fixed-satellite service downlinks to VSAT’s!


What’s the process?

• All countries are sovereign inside their border– Radio waves always know where to stop, eh?

• But no country can operate a satellite transmitter without ITU-R permission

• Border issues are often important

• So the most general set of rules, the Radio Regulations, is an international treaty, renegotiated every 4-5 years at a UN organ.



The ITU-R-R

• A UN agency in Geneva


The ITU-R-R

• A UN agency in Geneva

Entire ITU-R structure mirrored in US

USWP7A,B,C,D


The world is flat-- ITU Regions


Regional Groups

CITEL

APT

Arab

group

CEPT


For RAS, too

citel

apt

Arab

group

ceptcraf

rafcap

corf


And the IUCAF umbrella

• IUCAF– ICSU-chartered for IAU, COSPAR, URSI

– Historically, the vehicle for RAS representation

– Now being pressured to be more interdisciplinary

– http://www.iucaf.org

http://www.iucaf.org/

What’s hot now?

• RAS is bringing sensitive broadband instruments online opening new bands

• Some of these bands are becoming toxic– High power orbiting radars, 1-100 GHz– Cloud-mapping (CloudSat 94.05 GHz)– TerraSar-X earth mapping SAR at 9.3-9.9 GHz– Could burn up a RAS receiver in the (statistically)

unlikely event of a main-beam encounter


Where will it end

• Our operations are being pushed back onto reservations and very out of the way places– In spectrum too, above 80 GHz is where RA has

widest allocations

• We are creating and trying to get more recognition for Radio Quiet Zones and operation at frequencies > 275 GHz– At present, no RQZ will protect you from a

satellite or airplane, however toxic.


Where will it end

• Worrying ‘too much’ is just crazy-making– Worrying too little would be dangerous

• And illegal, being careful is in the Radio Regs

• We haven’t found effective means of mitigating unwanted emissions, except to avoid them

• We’re still working, despite ‘encroachments’

• If we were forced into space, we’d become vastly richer overnight


Harvey LisztArecibo July 2005 Harvey S. Liszt NRAO, CHARLOTTESVILLE.

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