Minutes from the
Agenda:
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
Minutes:
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.