OK, I get it now, its not just the AP, but the SU also.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
----- Original Message -----
From: Fred Goldstein
To: WISPA General List
Sent: Friday, September 24, 2010 2:57 PM
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: Brian Webster
To: '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: 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: Fred Goldstein
To: 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/
+1 617 795 2701
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ionary Consulting http://www.ionary.com/
+1 617 795 2701
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