This rule as it is written states that the ground elevation not
more than 75 meters HAAT. Remember that is the not actual ground
elevation of the site, it is the HAAT calculation. See my other
email with a HAAT report pasted within. My office at an elevation
of 1420 ft AMSL actually has a negative HAAT value. I think people
are misunderstanding how HAAT is calculated.
Brian
From: <mailto:wireless-boun...@wispa.org>wireless-boun...@wispa.org
[mailto:wireless-boun...@wispa.org] On Behalf Of Fred Goldstein
Sent: Friday, September 24, 2010 3:37 PM
To: WISPA General List
Subject: Re: [WISPA] FW: Transmit Antenna Height
At 9/24/2010 03:03 PM, you wrote:
Steve,
Here is another question to pose to the FCC. Does the HAAT
requirement include receive antennas. In otherwords, can no
clients be installed above the 76 meter HAAT level?
I see no mention of receive-only terminals, though I doubt anybody
asked. But if by receive you mean client (such as a Mode 1 CPE),
then the rules seem to ban those entirely, not just APs, from high ground:
"...We will therefore restrict fixed TV bands devices from
operating at locations where the HAAT of the ground is greater than
76 meters; this will allow use of an antenna at a height of up to
30 meters above ground level to provide an antenna HAAT of 106
meters. Accordingly, we are specifying that a fixed TV bands device
antenna may not be located at a site where the ground HAAT is
greater than 75 meters (246 feet). The ground HAAT is to be
calculated by the TV bands database using computational software
employing the methodology in Section 73.684(d) of the rules to
ensure that fixed devices comply with this requirement."
They cite to the IEEE's filing, but it didn't call for a ban;
instead it called for wider protection distances based on HAAT:
13.We recommend that HAAT be used to determine the required
separation distance from TV protected contours as described in the
Table below.6 The method for calculating HAAT should be the same as
was employed in Part 90 to protect the TV service from PLMRS. In
addition, we recommend no limits on the antenna height above ground
for fixed base stations.7 We further recommend that no changes in
the assumption of antenna heights of 10m AGL for fixed user
terminals (CPEs) be made for the purpose of calculating the
separation distance to the TV protected contour.
That would have been reasonable.
From: <mailto:wireless-boun...@wispa.org>wireless-boun...@wispa.org
[ mailto:wireless-boun...@wispa.org] On Behalf Of Fred Goldstein
Sent: Friday, September 24, 2010 2:57 PM
To: WISPA General List
Subject: Re: [WISPA] Transmit Antenna Height
At 9/24/2010 02:16 PM, Tom DeReggi wrote:
There is one other benefit of this.... No body else will be able to
install higher either.
Mounting lower to the ground, its more likely a WISP will be able
to install their own tower, and no longer have to pay huge
colocation costs on a commercial tower.
I predict more houses up on the hill, being the new TVWhitespace towers.
Although, aren't these low channel Whitespace omnis like giant, and
weight a ton?
No, Tom, you missed the poison pill. If somebody lives on a hill,
more than 76 meters above average terrain, then they are banned
from using fixed whitespace devices AT ALL. Not at 4W. Not at
1W. Just the flea-power portable devices, which are basically wireless mics.
This new rule needs to be changed.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
----- Original Message -----
From: <mailto:bwebs...@wirelessmapping.com>Brian Webster
To: <mailto:wireless@wispa.org>'WISPA General List'
Sent: Thursday, September 23, 2010 7:41 PM
Subject: Re: [WISPA] Transmit Antenna Height
But what if you are able to use spectrum around 200 or 300 MHz?
That certainly goes through trees.
Brian
From: <mailto:wireless-boun...@wispa.org>wireless-boun...@wispa.org
[mailto:wireless-boun...@wispa.org] On Behalf Of Tom DeReggi
Sent: Thursday, September 23, 2010 7:32 PM
To: WISPA General List
Subject: Re: [WISPA] Transmit Antenna Height
Yeah, that really sucks. Many areas needing served have thick
forest/trees easilly 70ft tall.
A 90ft height, just wouldn't allow enough of the signal to have
open air, and the signal would be going through trees most of the full path.
In 900Mhz, the difference between having the tower side over the
tree line and below the tree line can be the difference between a
quarter mile coverage and a 7 mile coverage in our market.
All be it, 700Mhz does have better NLOS propogation characteristics
than 900 does.
I would have liked to see that height doubled.
However, admittedly, it will allow much better spectrum re-use in
areas that have a limited number of channels available.
Spectrum reuse is one of the best ways to serve more people.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
----- Original Message -----
From: <mailto:fgoldst...@ionary.com>Fred Goldstein
To: <mailto:wireless@wispa.org>WISPA General List
Sent: Thursday, September 23, 2010 4:36 PM
Subject: Re: [WISPA] Transmit Antenna Height
This item alone may be the show-stopper, the poison pill that makes
it useless to WISPs in much of the country.
In places where the routine variation in elevation is more than 75
meters, there will be houses (subscribers) that are more than 76
meters AAT. I notice this in the areas I'm studying, both in the
east and in the upper midwest.
In a place like Kansas, nobody is >75m AAT. But in the woody
Berkshires of Western Massachusetts, the UHF space is needed to get
through the trees, and a significant share of houses are >75m
AAT. Also, if you want to cover a decent radius, the access point
needs to be up the hill too. 75 meters isn't a mountaintop; it's
just a little rise.
It makes no sense to absolutely ban fixed use at a site that is
100m AAT if the nearest protected-service contour is, say, 50 miles
away. A more sensible rule would be to follow broadcast practice,
and lower the ERP based on height, so that the distance to a given
signal strength contour is held constant as the height
rises. Hence a Class A FM station is allowed up to 15 miles, and
if it is more than 300 feet AAT, then it is allowed less than the
3000 watts ERP that apply at lower heights.
Maybe the lawyers want to have more petitions to argue over.
At 9/23/2010 04:07 PM, Rich Harnish wrote:
65. Decision. We decline to increase the maximum permitted transmit
antenna height above ground for fixed TV bands devices. As the
Commission stated in the Second Report and Order, the 30 meters
above ground limit was established as a balance between the
benefits of increasing TV bands device transmission range and the
need to minimize the impact on licensed services.129 Consistent
with the Commission's stated approach in the Second Report and
Order of taking a conservative approach in protecting authorized
services, we find the prudent course of action is to maintain the
previously adopted height limit. If, in the future, experience with
TV bands devices indicates that these devices could operate at
higher transmit heights without causing interference, the
Commission could revisit the height limit.
66. While we expect that specifying a limit on antenna height above
ground rather than above average terrain is satisfactory for
controlling interference to authorized services in the majority of
cases, we also recognize petitioners' concerns about the increased
potential for interference in instances where a fixed TV bands
device antenna is located on a local geographic high point such as
a hill or mountain.130 In such cases, the distance at which a TV
bands device signal could propagate would be significantly
increased, thus increasing the potential for interference to
authorized operations in the TV bands. We therefore conclude that
it is necessary to modify our rules to limit the antenna HAAT of a
fixed device as well as its antenna height above ground. In
considering a limit for antenna HAAT, we need to balance the
concerns for long range propagation from high points against the
typical variability of ground height that occurs in areas where
there are significant local high points we do not want to
preclude fixed devices from a large number of sites in areas where
there are rolling hills or a large number of relatively high points
that do not generally provide open, line-of-sight paths for
propagation over long distances. We find that limiting the fixed
device antenna HAAT to 106 meters (350 feet), as calculated by the
TV bands database, provides an appropriate balance of these
concerns. We will therefore restrict fixed TV bands devices from
operating at locations where the HAAT of the ground is greater than
76 meters; this will allow use of an antenna at a height of up to
30 meters above ground level to provide an antenna HAAT of 106
meters. Accordingly, we are specifying that a fixed TV bands device
antenna may not be located at a site where the ground HAAT is
greater than 75 meters (246 feet). The ground HAAT is to be
calculated by the TV bands database using computational software
employing the methodology in Section 73.684(d) of the rules to
ensure that fixed devices comply with this requirement.
130 The antenna height above ground is the distance from the
antenna center of radiation to the actual ground directly below the
antenna. To calculate the antenna height above average terrain
(HAAT), the average elevation of the surrounding terrain above mean
sea level must be determined along at least 8 evenly spaced radials
at distances from 3 to 16 km from the transmitter site. The HAAT is
the difference between the antenna height above mean sea level (the
antenna height above ground plus the site elevation) and the
average elevation of the surrounding terrain.
67. In reexamining this issue, we also note that the rules
currently do not indicate that fixed device antenna heights must be
provided to the database for use in determining available channels.
It was clearly the Commission's intent that fixed devices include
their height when querying the database because the available
channels for fixed devices cannot be determined without this
information.131 We are therefore modifying Sections 15.711(b)(3)
and 15.713(f)(3) to indicate that fixed devices must submit their
antenna height above ground to the database.
68. We continue to decline to establish height limits for
personal/portable devices. As the Commission stated in the Second
Report and Order, there is no practical way to enforce such limits,
and such limits are not necessary due to the different technical
and operational characteristics of personal/portable devices.
--
Fred Goldstein k1io fgoldstein "at" ionary.com
ionary
Consulting <http://www.ionary.com/>http://www.ionary.com/
+1 617 795 2701
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+1 617 795 2701
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+1 617 795 2701
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