[W1SMH] Pave Paws

[Ken Reynolds]

Don't know if you guys saw this or not?
The FCC, ARRL representatives and agents of the various US Air Force
units working on developing a plan to mitigate alleged interference
from 70 cm ham radio repeaters to PAVE PAWS radar systems on both
coasts met February 20 via conference call. The purpose of the
conference was to review the status of the mitigation plans at both
sites: the Massachusetts Military Reservation on Cape Cod and Beale
AFB, north of Sacramento, California.

Thanks to the cooperation and assistance of the involved repeater
owners on Cape Cod, ARRL Regulatory Branch Manager Dan Henderson,
N1ND, said, "I am pleased to be able to pass along that at this time
that the Department of Defense has determined that the levels of
harmful interference to the PAVE PAWS radar site on Cape Cod have been
sufficiently reduced. As part of this determination, they are not
rescheduling additional follow-up testing for that area until sometime
in 2009."

Henderson said that this decision doesn't mean New England is back to
pre-mitigation repeater operation: "Any mitigation steps that have
been taken should remain in place. A repeater that has gone off the
air should not be simply turned back on at its original power level -
its previously determined mitigation standard still applies in order
to protect the primary user from harmful interference."

Henderson stressed that the entire process is ongoing. "The high
degree of voluntary cooperation shown by the owners of Air
Force-identified repeaters has helped demonstrate to the DoD that the
amateur community takes its responsibility seriously. This should help
us retain access to the band in the long run."

Repeater Coordination

During the discussion of the Cape Cod radar during the teleconference,
the ARRL broached the topic of allowing the resumption of coordinating
new repeaters on the 70 cm band in New England. The Air Force has
agreed in principle to allow the New England Spectrum Management
Council (NESMC) to resume coordination efforts under certain
conditions. "These include that in addition to NESMC's normal
coordination policies, Longley-Rice signal strength plots are prepared
to determine expected signal strength at the radar site," Henderson
said.

Henderson said that the ARRL has a "fairly good understanding of what
strength level at the site should be workable, even though the DoD has
not given us specific information on the sensitivity of the radar. The
Longley-Rice plots should indicate if the operating parameters of the
proposed repeater might be sufficient to prevent harmful interference
to the radar site. The Longley-Rice plots are not the 'last word' in
the process, but are a good tool giving the repeater owner and NESMC a
reasonable assessment of possible problems."

Henderson reiterated that "any specific mitigation number from the Air
Force is an exact measurement, not a 'predicted' number from a
computer analysis."

Once NESMC approves a tentative coordination, Henderson explained that
NESMC would forward the complete information on the new repeater to
the Air Force for authorization on a case-by-case basis, as provided
for in Title 47 §2.106 Footnote US7. "During a 60 day trial period,
the Air Force would contact NESMC for an immediate shut-down of a new
repeater causing harmful interference. If that happens the new
repeater would have to remain off the air until it can be successfully
mitigated."

While this new process is a bit burdensome to NESMC and the repeater
owners, it goes a long way toward keeping Amateur Radio in a position
where 70 cm operation can grow with careful attention to the effect of
our operations on the primary users.