Minutes from the
1. Electric Fence RFI Memo
2. RFI Risk Assessment and Proposed Proactive Measures
Attendees: J. Acree, R. Fisher, F. Ghigo, R. Lacasse, R. McCullough, C. Niday, D. Wirt,
W. Sizemore, C. Beaudet
3. Jeff provided copies of the latest revision of the staff memo regarding electric fence RFI and an open discussion was held. Frank wondered how the information might be disseminated to the local community. WVMR and the local paper were identified as possibilities, but Frank noted that it might be preferable to endeavor to raise local awareness without involving the whole county. Flyers in the local stores were proposed as a possible way to accomplish this. Randy noted that using real wire vs. polywire, in addition to reducing RFI risk, has the added benefit of improving fence reliability as it is not as easily broken. It was agreed that this should be added to the memo. Denise pointed out the kept vs. keep typo that seems to keep hanging on. Wes questioned who would pay for required upgrades. Jeff felt this would have to be addressed on a case by case basis. It was agreed that the discussed changes and corrections would be made and the memo forwarded to the staff.
4. Jeff provided some background on the need to develop streamlined coordination criteria for 802.11 b/g devices. A high level briefing on typical system architecture, part 15.247 rules, and the 802.11b standard was provided. Jeff noted that we need to assure spurious emissions are taken into account and indicated that, per part 15.247 (c), these should be 20 dB down. Denise asked what the limit allowance should be at harmonic frequencies. Rick proposed that 3dB be added to the 30.41 dB allowance at the first harmonic to allow for the power being spread across twice the bandwidth. Carla expressed concern that the spurious emissions of COTS 802.11b devices may not meet the part 15.247 (c) requirements per our anechoic chamber measurements. Jeff noted that due to our test methodology, direct comparison of the fundamental and harmonic responses of the tested devices is difficult to interpret. It was agreed, however, that we should keep an eye on spurious emissions to assure our assumption that 802.11b devices meet 15.247(c), is valid. Frank wondered if coordinated shutdowns might be possible. A brief discussion of how homeowners at Snowshoe would be informed of RFI concerns was also undertaken.
The balance of the meeting was used to discuss community coordination criteria for 802.11b and g devices as follows:
· The NRQZ limit at 2412 MHz with a limit allowance of 30.41 dB will be used to evaluate sites.
· For site evaluations that involve point to multipoint connections with “random” ancillary devices, we will use the max power allowed per section 15.247 (b)(3 & 4) (36 dBi), or the actual performance parameters of the access point, whichever is the most restrictive.
· For point to point sites, the actual device specifications will be used. For point to multipoint sites where there is a very high degree of certainty regarding ancillary devices, this approach may also be considered.
· Allowances for buildings and being underground will be on a case by case basis. Chuck proposed investigating the possibility that well developed tables that are available for other services might be used. Other suggestions included the incorporation of an equivalent obstacle in propagation analysis and direct measurement of SE.
· It was agreed that the same criteria would be applied to 802.11b and g.
· It was agreed that wireless LAN equipment should not be used on site or in Observatory housing. It was further stipulated that unlicensed wireless equipment in general should not be used on site. Not even in shielded rooms. Several avenues of communication to convey this policy were offered, including: A memo in the visitor’s packet; memo included with residence hall check-in envelope; and an all hands memo. Jeff agreed to coordinate the preparation and distribution of an all hands memo stating this.
· As the Commission’s rules regarding unlicensed devices are many and seemingly ever-changing, it was agreed that we should not endeavor to serve as general spectrum police. Jeff’s hope is that this will better enable us to stay focused on specific rules that will further the protection of our facility from harmful RFI.
· A remaining concern expressed by Rick was our inability to account for multiple devices on the same channel or overlapping channels. It was agreed that he and Jeff would look into it further and report back.
· Near the end of the meeting Denise presented a coverage map of the high risk areas for the deployment of 802.11b devices and noted that is was a work in progress.