As we work on the next generation of radio telescopes, we often forget that the most important national facility for radio astronomy is clear spectrum in which to do it. These days, with the frequency bands allocated for radio astronomy being surrounded for and often right next to radio services using airborne and space borne transmitters, we have to get into the bear pit with everyone else, and fight to keep our spectrum.
I have just got back from a meeting in Geneva of the rather opaquely named UN/ITU Task Group 1-9. This committee is tasked to identify what are the radio services most likely to cause problems for radio astronomy and to see what can be done by the service causing the interference and what radio astronomers can do to minimize its impact. We cannot argue that our bands are our bands, and keep out, because the problem international spectrum management is faced with is squeezing more and more radio services into a spectrum that cannot be made bigger, so everyone gets compressed a bit. It means we have to solidly justify our position over and over again, band by band. Radio Astronomy is recognized as a radio service like all the others, but no more or less important than those others. This work in Geneva is therefore unavoidable, but we have done reasonably well so far.
The biggest fireworks in Geneva came from a problem that has been around for some time. At the time satellite navigation systems were being implemented, the Soviet Union set up a system called GLONASS, which transmits at frequencies just below the 1610.3-1613.8 MHz radio astronomy band -- the most important band used for observations of OH. This system uses a modulation system that splatters a lot of signal into that radio astronomy band. The appearance of this interference caused a major furor and led to the Soviet Union entering into an agreement to reduce that interference level by implementing filters and changes in the way the system is used. Between then and now the Soviet Union ceased to exist and the agreement was inherited by Russia. Unfortunately, with slimmer resources, Russia has not really been able to meet the agreed timetable.
This would have been reluctantly acceptable in Geneva if Russia would have simply stated that, and asked for more time. However, this is not what happened. Russia essentially proposed that no more could be done and that the agreement should be deemed satisfied. This caused a major "extensive, far-reaching and candid discussion". Condemnation was unanimous. The result of these interchanges was that Russia accepted the timetable of starting to place the new, improved satellites in service by the beginning of 2006. However, the old satellites will remain in service until they fail and are replaced, so the improvement in the interference situation will be take years.
In the previous agreement, the targets for suppression of the interference were quoted in terms of emission per satellite; at that time the tools for modeling the total interference from several satellites above the horizon did not exist. Now they do. Current assessments are that the total GLONASS interference at a radio telescope will be more than 100 times the level at which data degradation becomes significant. As pointed out at the meeting, this is tantamount to having observations unacceptably degraded for 98.8% (sic) of the time. This situation will take a while to deal with. A major concern is not to imply any form of acquiescence with this, because it could be used to undermine our ability to protect other radio astronomy bands. At this point it is not clear what the future will bring for this band. If nothing else it underlines the need for radio astronomers to keep their eyes on the ball with protecting radio spectrum. We are committing major resources to the next generation of radio telescopes, and we would like to know they have a good chance of being usable.
Another major issue at the moment is the proposal to transmit data over electrical power lines. A feasibility study has been under way for some time in Sault Ste. Marie. The results have been inconclusive. Because these systems could be widespread, our position as radio astronomers is that it must be demonstrated beforehand that our radio astronomy operations won't be affected. However, the US is deploying these systems, and Canada will probably, as is fairly usual, have to "harmonize with the US". This same thing will probably happen with the deployment of Ultra-Wideband technologies. Discussions are still under way here, but US deployment is going ahead. Because these devices will be used on cars and in homes, diffusion across the border will be inevitable.
Boeing is implementing high-speed internet capabilities on new airliners. These will operate at about 14 GHz, communicating via satellite links. Boeing has agreed to build into the system the facility for changing or ceasing operation when within specified distances from radio observatories.
Allocation of frequencies to 1000 GHz is now under study, and will probably be finalized for the next World Radio Conference in 2007. We are working on our claims for slices of this valuable chunk of new spectrum.
A big plus at the moment is our excellent working relationship with Industry Canada. We don't always get IC to agree with us, but we do have good lines of communication and in general radio astronomy protection issues are being taken seriously and properly discussed. In addition, there are always at least six radio astronomers present at the meetings in Geneva, scattered around various national delegations. Given the current vigorous competition for space in the radio spectrum, this is not too many.
ken.tapping@nrc-cnrc.gc.ca